From 20431706a863f92cb37dc512fef6e48d192aaf2c Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:11:38 +0200 Subject: Merging upstream version 1.66.0+dfsg1. Signed-off-by: Daniel Baumann --- compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs | 1540 ++++++++++++++ .../rustc_hir_typeck/src/fn_ctxt/arg_matrix.rs | 383 ++++ compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs | 2236 ++++++++++++++++++++ compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs | 312 +++ .../rustc_hir_typeck/src/fn_ctxt/suggestions.rs | 1250 +++++++++++ 5 files changed, 5721 insertions(+) create mode 100644 compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs create mode 100644 compiler/rustc_hir_typeck/src/fn_ctxt/arg_matrix.rs create mode 100644 compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs create mode 100644 compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs create mode 100644 compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs (limited to 'compiler/rustc_hir_typeck/src/fn_ctxt') diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs new file mode 100644 index 000000000..6a1cffe3e --- /dev/null +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs @@ -0,0 +1,1540 @@ +use crate::callee::{self, DeferredCallResolution}; +use crate::method::{self, MethodCallee, SelfSource}; +use crate::rvalue_scopes; +use crate::{BreakableCtxt, Diverges, Expectation, FnCtxt, LocalTy}; +use rustc_data_structures::captures::Captures; +use rustc_data_structures::fx::FxHashSet; +use rustc_errors::{Applicability, Diagnostic, ErrorGuaranteed, MultiSpan}; +use rustc_hir as hir; +use rustc_hir::def::{CtorOf, DefKind, Res}; +use rustc_hir::def_id::DefId; +use rustc_hir::lang_items::LangItem; +use rustc_hir::{ExprKind, GenericArg, Node, QPath}; +use rustc_hir_analysis::astconv::{ + AstConv, CreateSubstsForGenericArgsCtxt, ExplicitLateBound, GenericArgCountMismatch, + GenericArgCountResult, IsMethodCall, PathSeg, +}; +use rustc_infer::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse}; +use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282; +use rustc_infer::infer::{InferOk, InferResult}; +use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability}; +use rustc_middle::ty::fold::TypeFoldable; +use rustc_middle::ty::visit::TypeVisitable; +use rustc_middle::ty::{ + self, AdtKind, CanonicalUserType, DefIdTree, EarlyBinder, GenericParamDefKind, ToPolyTraitRef, + ToPredicate, Ty, UserType, +}; +use rustc_middle::ty::{GenericArgKind, InternalSubsts, SubstsRef, UserSelfTy, UserSubsts}; +use rustc_session::lint; +use rustc_span::def_id::LocalDefId; +use rustc_span::hygiene::DesugaringKind; +use rustc_span::symbol::{kw, sym, Ident}; +use rustc_span::{Span, DUMMY_SP}; +use rustc_trait_selection::infer::InferCtxtExt as _; +use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _; +use rustc_trait_selection::traits::{ + self, ObligationCause, ObligationCauseCode, TraitEngine, TraitEngineExt, +}; + +use std::collections::hash_map::Entry; +use std::slice; + +impl<'a, 'tcx> FnCtxt<'a, 'tcx> { + /// Produces warning on the given node, if the current point in the + /// function is unreachable, and there hasn't been another warning. + pub(in super::super) fn warn_if_unreachable(&self, id: hir::HirId, span: Span, kind: &str) { + // FIXME: Combine these two 'if' expressions into one once + // let chains are implemented + if let Diverges::Always { span: orig_span, custom_note } = self.diverges.get() { + // If span arose from a desugaring of `if` or `while`, then it is the condition itself, + // which diverges, that we are about to lint on. This gives suboptimal diagnostics. + // Instead, stop here so that the `if`- or `while`-expression's block is linted instead. + if !span.is_desugaring(DesugaringKind::CondTemporary) + && !span.is_desugaring(DesugaringKind::Async) + && !orig_span.is_desugaring(DesugaringKind::Await) + { + self.diverges.set(Diverges::WarnedAlways); + + debug!("warn_if_unreachable: id={:?} span={:?} kind={}", id, span, kind); + + let msg = format!("unreachable {}", kind); + self.tcx().struct_span_lint_hir( + lint::builtin::UNREACHABLE_CODE, + id, + span, + &msg, + |lint| { + lint.span_label(span, &msg).span_label( + orig_span, + custom_note + .unwrap_or("any code following this expression is unreachable"), + ) + }, + ) + } + } + } + + /// Resolves type and const variables in `ty` if possible. Unlike the infcx + /// version (resolve_vars_if_possible), this version will + /// also select obligations if it seems useful, in an effort + /// to get more type information. + pub(in super::super) fn resolve_vars_with_obligations(&self, ty: Ty<'tcx>) -> Ty<'tcx> { + self.resolve_vars_with_obligations_and_mutate_fulfillment(ty, |_| {}) + } + + #[instrument(skip(self, mutate_fulfillment_errors), level = "debug", ret)] + pub(in super::super) fn resolve_vars_with_obligations_and_mutate_fulfillment( + &self, + mut ty: Ty<'tcx>, + mutate_fulfillment_errors: impl Fn(&mut Vec>), + ) -> Ty<'tcx> { + // No Infer()? Nothing needs doing. + if !ty.has_non_region_infer() { + debug!("no inference var, nothing needs doing"); + return ty; + } + + // If `ty` is a type variable, see whether we already know what it is. + ty = self.resolve_vars_if_possible(ty); + if !ty.has_non_region_infer() { + debug!(?ty); + return ty; + } + + // If not, try resolving pending obligations as much as + // possible. This can help substantially when there are + // indirect dependencies that don't seem worth tracking + // precisely. + self.select_obligations_where_possible(false, mutate_fulfillment_errors); + self.resolve_vars_if_possible(ty) + } + + pub(in super::super) fn record_deferred_call_resolution( + &self, + closure_def_id: LocalDefId, + r: DeferredCallResolution<'tcx>, + ) { + let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut(); + deferred_call_resolutions.entry(closure_def_id).or_default().push(r); + } + + pub(in super::super) fn remove_deferred_call_resolutions( + &self, + closure_def_id: LocalDefId, + ) -> Vec> { + let mut deferred_call_resolutions = self.deferred_call_resolutions.borrow_mut(); + deferred_call_resolutions.remove(&closure_def_id).unwrap_or_default() + } + + pub fn tag(&self) -> String { + format!("{:p}", self) + } + + pub fn local_ty(&self, span: Span, nid: hir::HirId) -> LocalTy<'tcx> { + self.locals.borrow().get(&nid).cloned().unwrap_or_else(|| { + span_bug!(span, "no type for local variable {}", self.tcx.hir().node_to_string(nid)) + }) + } + + #[inline] + pub fn write_ty(&self, id: hir::HirId, ty: Ty<'tcx>) { + debug!("write_ty({:?}, {:?}) in fcx {}", id, self.resolve_vars_if_possible(ty), self.tag()); + self.typeck_results.borrow_mut().node_types_mut().insert(id, ty); + + if ty.references_error() { + self.has_errors.set(true); + self.set_tainted_by_errors(); + } + } + + pub fn write_field_index(&self, hir_id: hir::HirId, index: usize) { + self.typeck_results.borrow_mut().field_indices_mut().insert(hir_id, index); + } + + #[instrument(level = "debug", skip(self))] + pub(in super::super) fn write_resolution( + &self, + hir_id: hir::HirId, + r: Result<(DefKind, DefId), ErrorGuaranteed>, + ) { + self.typeck_results.borrow_mut().type_dependent_defs_mut().insert(hir_id, r); + } + + #[instrument(level = "debug", skip(self))] + pub fn write_method_call(&self, hir_id: hir::HirId, method: MethodCallee<'tcx>) { + self.write_resolution(hir_id, Ok((DefKind::AssocFn, method.def_id))); + self.write_substs(hir_id, method.substs); + + // When the method is confirmed, the `method.substs` includes + // parameters from not just the method, but also the impl of + // the method -- in particular, the `Self` type will be fully + // resolved. However, those are not something that the "user + // specified" -- i.e., those types come from the inferred type + // of the receiver, not something the user wrote. So when we + // create the user-substs, we want to replace those earlier + // types with just the types that the user actually wrote -- + // that is, those that appear on the *method itself*. + // + // As an example, if the user wrote something like + // `foo.bar::(...)` -- the `Self` type here will be the + // type of `foo` (possibly adjusted), but we don't want to + // include that. We want just the `[_, u32]` part. + if !method.substs.is_empty() { + let method_generics = self.tcx.generics_of(method.def_id); + if !method_generics.params.is_empty() { + let user_type_annotation = self.probe(|_| { + let user_substs = UserSubsts { + substs: InternalSubsts::for_item(self.tcx, method.def_id, |param, _| { + let i = param.index as usize; + if i < method_generics.parent_count { + self.var_for_def(DUMMY_SP, param) + } else { + method.substs[i] + } + }), + user_self_ty: None, // not relevant here + }; + + self.canonicalize_user_type_annotation(UserType::TypeOf( + method.def_id, + user_substs, + )) + }); + + debug!("write_method_call: user_type_annotation={:?}", user_type_annotation); + self.write_user_type_annotation(hir_id, user_type_annotation); + } + } + } + + pub fn write_substs(&self, node_id: hir::HirId, substs: SubstsRef<'tcx>) { + if !substs.is_empty() { + debug!("write_substs({:?}, {:?}) in fcx {}", node_id, substs, self.tag()); + + self.typeck_results.borrow_mut().node_substs_mut().insert(node_id, substs); + } + } + + /// Given the substs that we just converted from the HIR, try to + /// canonicalize them and store them as user-given substitutions + /// (i.e., substitutions that must be respected by the NLL check). + /// + /// This should be invoked **before any unifications have + /// occurred**, so that annotations like `Vec<_>` are preserved + /// properly. + #[instrument(skip(self), level = "debug")] + pub fn write_user_type_annotation_from_substs( + &self, + hir_id: hir::HirId, + def_id: DefId, + substs: SubstsRef<'tcx>, + user_self_ty: Option>, + ) { + debug!("fcx {}", self.tag()); + + if Self::can_contain_user_lifetime_bounds((substs, user_self_ty)) { + let canonicalized = self.canonicalize_user_type_annotation(UserType::TypeOf( + def_id, + UserSubsts { substs, user_self_ty }, + )); + debug!(?canonicalized); + self.write_user_type_annotation(hir_id, canonicalized); + } + } + + #[instrument(skip(self), level = "debug")] + pub fn write_user_type_annotation( + &self, + hir_id: hir::HirId, + canonical_user_type_annotation: CanonicalUserType<'tcx>, + ) { + debug!("fcx {}", self.tag()); + + if !canonical_user_type_annotation.is_identity() { + self.typeck_results + .borrow_mut() + .user_provided_types_mut() + .insert(hir_id, canonical_user_type_annotation); + } else { + debug!("skipping identity substs"); + } + } + + #[instrument(skip(self, expr), level = "debug")] + pub fn apply_adjustments(&self, expr: &hir::Expr<'_>, adj: Vec>) { + debug!("expr = {:#?}", expr); + + if adj.is_empty() { + return; + } + + for a in &adj { + if let Adjust::NeverToAny = a.kind { + if a.target.is_ty_var() { + self.diverging_type_vars.borrow_mut().insert(a.target); + debug!("apply_adjustments: adding `{:?}` as diverging type var", a.target); + } + } + } + + let autoborrow_mut = adj.iter().any(|adj| { + matches!( + adj, + &Adjustment { + kind: Adjust::Borrow(AutoBorrow::Ref(_, AutoBorrowMutability::Mut { .. })), + .. + } + ) + }); + + match self.typeck_results.borrow_mut().adjustments_mut().entry(expr.hir_id) { + Entry::Vacant(entry) => { + entry.insert(adj); + } + Entry::Occupied(mut entry) => { + debug!(" - composing on top of {:?}", entry.get()); + match (&entry.get()[..], &adj[..]) { + // Applying any adjustment on top of a NeverToAny + // is a valid NeverToAny adjustment, because it can't + // be reached. + (&[Adjustment { kind: Adjust::NeverToAny, .. }], _) => return, + ( + &[ + Adjustment { kind: Adjust::Deref(_), .. }, + Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(..)), .. }, + ], + &[ + Adjustment { kind: Adjust::Deref(_), .. }, + .., // Any following adjustments are allowed. + ], + ) => { + // A reborrow has no effect before a dereference. + } + // FIXME: currently we never try to compose autoderefs + // and ReifyFnPointer/UnsafeFnPointer, but we could. + _ => { + self.tcx.sess.delay_span_bug( + expr.span, + &format!( + "while adjusting {:?}, can't compose {:?} and {:?}", + expr, + entry.get(), + adj + ), + ); + } + } + *entry.get_mut() = adj; + } + } + + // If there is an mutable auto-borrow, it is equivalent to `&mut `. + // In this case implicit use of `Deref` and `Index` within `` should + // instead be `DerefMut` and `IndexMut`, so fix those up. + if autoborrow_mut { + self.convert_place_derefs_to_mutable(expr); + } + } + + /// Basically whenever we are converting from a type scheme into + /// the fn body space, we always want to normalize associated + /// types as well. This function combines the two. + fn instantiate_type_scheme(&self, span: Span, substs: SubstsRef<'tcx>, value: T) -> T + where + T: TypeFoldable<'tcx>, + { + debug!("instantiate_type_scheme(value={:?}, substs={:?})", value, substs); + let value = EarlyBinder(value).subst(self.tcx, substs); + let result = self.normalize_associated_types_in(span, value); + debug!("instantiate_type_scheme = {:?}", result); + result + } + + /// As `instantiate_type_scheme`, but for the bounds found in a + /// generic type scheme. + pub(in super::super) fn instantiate_bounds( + &self, + span: Span, + def_id: DefId, + substs: SubstsRef<'tcx>, + ) -> (ty::InstantiatedPredicates<'tcx>, Vec) { + let bounds = self.tcx.predicates_of(def_id); + let spans: Vec = bounds.predicates.iter().map(|(_, span)| *span).collect(); + let result = bounds.instantiate(self.tcx, substs); + let result = self.normalize_associated_types_in(span, result); + debug!( + "instantiate_bounds(bounds={:?}, substs={:?}) = {:?}, {:?}", + bounds, substs, result, spans, + ); + (result, spans) + } + + pub(in super::super) fn normalize_associated_types_in(&self, span: Span, value: T) -> T + where + T: TypeFoldable<'tcx>, + { + self.inh.normalize_associated_types_in(span, self.body_id, self.param_env, value) + } + + pub(in super::super) fn normalize_associated_types_in_as_infer_ok( + &self, + span: Span, + value: T, + ) -> InferOk<'tcx, T> + where + T: TypeFoldable<'tcx>, + { + self.inh.partially_normalize_associated_types_in( + ObligationCause::misc(span, self.body_id), + self.param_env, + value, + ) + } + + pub(in super::super) fn normalize_op_associated_types_in_as_infer_ok( + &self, + span: Span, + value: T, + opt_input_expr: Option<&hir::Expr<'_>>, + ) -> InferOk<'tcx, T> + where + T: TypeFoldable<'tcx>, + { + self.inh.partially_normalize_associated_types_in( + ObligationCause::new( + span, + self.body_id, + traits::BinOp { + rhs_span: opt_input_expr.map(|expr| expr.span), + is_lit: opt_input_expr + .map_or(false, |expr| matches!(expr.kind, ExprKind::Lit(_))), + output_ty: None, + }, + ), + self.param_env, + value, + ) + } + + pub fn require_type_meets( + &self, + ty: Ty<'tcx>, + span: Span, + code: traits::ObligationCauseCode<'tcx>, + def_id: DefId, + ) { + self.register_bound(ty, def_id, traits::ObligationCause::new(span, self.body_id, code)); + } + + pub fn require_type_is_sized( + &self, + ty: Ty<'tcx>, + span: Span, + code: traits::ObligationCauseCode<'tcx>, + ) { + if !ty.references_error() { + let lang_item = self.tcx.require_lang_item(LangItem::Sized, None); + self.require_type_meets(ty, span, code, lang_item); + } + } + + pub fn require_type_is_sized_deferred( + &self, + ty: Ty<'tcx>, + span: Span, + code: traits::ObligationCauseCode<'tcx>, + ) { + if !ty.references_error() { + self.deferred_sized_obligations.borrow_mut().push((ty, span, code)); + } + } + + pub fn register_bound( + &self, + ty: Ty<'tcx>, + def_id: DefId, + cause: traits::ObligationCause<'tcx>, + ) { + if !ty.references_error() { + self.fulfillment_cx.borrow_mut().register_bound( + self, + self.param_env, + ty, + def_id, + cause, + ); + } + } + + pub fn to_ty(&self, ast_t: &hir::Ty<'_>) -> Ty<'tcx> { + let t = >::ast_ty_to_ty(self, ast_t); + self.register_wf_obligation(t.into(), ast_t.span, traits::WellFormed(None)); + t + } + + pub fn to_ty_saving_user_provided_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> { + let ty = self.to_ty(ast_ty); + debug!("to_ty_saving_user_provided_ty: ty={:?}", ty); + + if Self::can_contain_user_lifetime_bounds(ty) { + let c_ty = self.canonicalize_response(UserType::Ty(ty)); + debug!("to_ty_saving_user_provided_ty: c_ty={:?}", c_ty); + self.typeck_results.borrow_mut().user_provided_types_mut().insert(ast_ty.hir_id, c_ty); + } + + ty + } + + pub fn array_length_to_const(&self, length: &hir::ArrayLen) -> ty::Const<'tcx> { + match length { + &hir::ArrayLen::Infer(_, span) => self.ct_infer(self.tcx.types.usize, None, span), + hir::ArrayLen::Body(anon_const) => { + let const_def_id = self.tcx.hir().local_def_id(anon_const.hir_id); + let span = self.tcx.hir().span(anon_const.hir_id); + let c = ty::Const::from_anon_const(self.tcx, const_def_id); + self.register_wf_obligation(c.into(), span, ObligationCauseCode::WellFormed(None)); + self.normalize_associated_types_in(span, c) + } + } + } + + pub fn const_arg_to_const( + &self, + ast_c: &hir::AnonConst, + param_def_id: DefId, + ) -> ty::Const<'tcx> { + let const_def = ty::WithOptConstParam { + did: self.tcx.hir().local_def_id(ast_c.hir_id), + const_param_did: Some(param_def_id), + }; + let c = ty::Const::from_opt_const_arg_anon_const(self.tcx, const_def); + self.register_wf_obligation( + c.into(), + self.tcx.hir().span(ast_c.hir_id), + ObligationCauseCode::WellFormed(None), + ); + c + } + + // If the type given by the user has free regions, save it for later, since + // NLL would like to enforce those. Also pass in types that involve + // projections, since those can resolve to `'static` bounds (modulo #54940, + // which hopefully will be fixed by the time you see this comment, dear + // reader, although I have my doubts). Also pass in types with inference + // types, because they may be repeated. Other sorts of things are already + // sufficiently enforced with erased regions. =) + fn can_contain_user_lifetime_bounds(t: T) -> bool + where + T: TypeVisitable<'tcx>, + { + t.has_free_regions() || t.has_projections() || t.has_infer_types() + } + + pub fn node_ty(&self, id: hir::HirId) -> Ty<'tcx> { + match self.typeck_results.borrow().node_types().get(id) { + Some(&t) => t, + None if self.is_tainted_by_errors() => self.tcx.ty_error(), + None => { + bug!( + "no type for node {}: {} in fcx {}", + id, + self.tcx.hir().node_to_string(id), + self.tag() + ); + } + } + } + + pub fn node_ty_opt(&self, id: hir::HirId) -> Option> { + match self.typeck_results.borrow().node_types().get(id) { + Some(&t) => Some(t), + None if self.is_tainted_by_errors() => Some(self.tcx.ty_error()), + None => None, + } + } + + /// Registers an obligation for checking later, during regionck, that `arg` is well-formed. + pub fn register_wf_obligation( + &self, + arg: ty::GenericArg<'tcx>, + span: Span, + code: traits::ObligationCauseCode<'tcx>, + ) { + // WF obligations never themselves fail, so no real need to give a detailed cause: + let cause = traits::ObligationCause::new(span, self.body_id, code); + self.register_predicate(traits::Obligation::new( + cause, + self.param_env, + ty::Binder::dummy(ty::PredicateKind::WellFormed(arg)).to_predicate(self.tcx), + )); + } + + /// Registers obligations that all `substs` are well-formed. + pub fn add_wf_bounds(&self, substs: SubstsRef<'tcx>, expr: &hir::Expr<'_>) { + for arg in substs.iter().filter(|arg| { + matches!(arg.unpack(), GenericArgKind::Type(..) | GenericArgKind::Const(..)) + }) { + self.register_wf_obligation(arg, expr.span, traits::WellFormed(None)); + } + } + + // FIXME(arielb1): use this instead of field.ty everywhere + // Only for fields! Returns for methods> + // Indifferent to privacy flags + pub fn field_ty( + &self, + span: Span, + field: &'tcx ty::FieldDef, + substs: SubstsRef<'tcx>, + ) -> Ty<'tcx> { + self.normalize_associated_types_in(span, field.ty(self.tcx, substs)) + } + + pub(in super::super) fn resolve_rvalue_scopes(&self, def_id: DefId) { + let scope_tree = self.tcx.region_scope_tree(def_id); + let rvalue_scopes = { rvalue_scopes::resolve_rvalue_scopes(self, &scope_tree, def_id) }; + let mut typeck_results = self.inh.typeck_results.borrow_mut(); + typeck_results.rvalue_scopes = rvalue_scopes; + } + + pub(in super::super) fn resolve_generator_interiors(&self, def_id: DefId) { + let mut generators = self.deferred_generator_interiors.borrow_mut(); + for (body_id, interior, kind) in generators.drain(..) { + self.select_obligations_where_possible(false, |_| {}); + crate::generator_interior::resolve_interior(self, def_id, body_id, interior, kind); + } + } + + #[instrument(skip(self), level = "debug")] + pub(in super::super) fn select_all_obligations_or_error(&self) { + let mut errors = self.fulfillment_cx.borrow_mut().select_all_or_error(&self); + + if !errors.is_empty() { + self.adjust_fulfillment_errors_for_expr_obligation(&mut errors); + self.err_ctxt().report_fulfillment_errors(&errors, self.inh.body_id, false); + } + } + + /// Select as many obligations as we can at present. + pub(in super::super) fn select_obligations_where_possible( + &self, + fallback_has_occurred: bool, + mutate_fulfillment_errors: impl Fn(&mut Vec>), + ) { + let mut result = self.fulfillment_cx.borrow_mut().select_where_possible(self); + if !result.is_empty() { + mutate_fulfillment_errors(&mut result); + self.adjust_fulfillment_errors_for_expr_obligation(&mut result); + self.err_ctxt().report_fulfillment_errors( + &result, + self.inh.body_id, + fallback_has_occurred, + ); + } + } + + /// For the overloaded place expressions (`*x`, `x[3]`), the trait + /// returns a type of `&T`, but the actual type we assign to the + /// *expression* is `T`. So this function just peels off the return + /// type by one layer to yield `T`. + pub(in super::super) fn make_overloaded_place_return_type( + &self, + method: MethodCallee<'tcx>, + ) -> ty::TypeAndMut<'tcx> { + // extract method return type, which will be &T; + let ret_ty = method.sig.output(); + + // method returns &T, but the type as visible to user is T, so deref + ret_ty.builtin_deref(true).unwrap() + } + + #[instrument(skip(self), level = "debug")] + fn self_type_matches_expected_vid( + &self, + trait_ref: ty::PolyTraitRef<'tcx>, + expected_vid: ty::TyVid, + ) -> bool { + let self_ty = self.shallow_resolve(trait_ref.skip_binder().self_ty()); + debug!(?self_ty); + + match *self_ty.kind() { + ty::Infer(ty::TyVar(found_vid)) => { + // FIXME: consider using `sub_root_var` here so we + // can see through subtyping. + let found_vid = self.root_var(found_vid); + debug!("self_type_matches_expected_vid - found_vid={:?}", found_vid); + expected_vid == found_vid + } + _ => false, + } + } + + #[instrument(skip(self), level = "debug")] + pub(in super::super) fn obligations_for_self_ty<'b>( + &'b self, + self_ty: ty::TyVid, + ) -> impl Iterator, traits::PredicateObligation<'tcx>)> + + Captures<'tcx> + + 'b { + // FIXME: consider using `sub_root_var` here so we + // can see through subtyping. + let ty_var_root = self.root_var(self_ty); + trace!("pending_obligations = {:#?}", self.fulfillment_cx.borrow().pending_obligations()); + + self.fulfillment_cx + .borrow() + .pending_obligations() + .into_iter() + .filter_map(move |obligation| { + let bound_predicate = obligation.predicate.kind(); + match bound_predicate.skip_binder() { + ty::PredicateKind::Projection(data) => Some(( + bound_predicate.rebind(data).required_poly_trait_ref(self.tcx), + obligation, + )), + ty::PredicateKind::Trait(data) => { + Some((bound_predicate.rebind(data).to_poly_trait_ref(), obligation)) + } + ty::PredicateKind::Subtype(..) => None, + ty::PredicateKind::Coerce(..) => None, + ty::PredicateKind::RegionOutlives(..) => None, + ty::PredicateKind::TypeOutlives(..) => None, + ty::PredicateKind::WellFormed(..) => None, + ty::PredicateKind::ObjectSafe(..) => None, + ty::PredicateKind::ConstEvaluatable(..) => None, + ty::PredicateKind::ConstEquate(..) => None, + // N.B., this predicate is created by breaking down a + // `ClosureType: FnFoo()` predicate, where + // `ClosureType` represents some `Closure`. It can't + // possibly be referring to the current closure, + // because we haven't produced the `Closure` for + // this closure yet; this is exactly why the other + // code is looking for a self type of an unresolved + // inference variable. + ty::PredicateKind::ClosureKind(..) => None, + ty::PredicateKind::TypeWellFormedFromEnv(..) => None, + } + }) + .filter(move |(tr, _)| self.self_type_matches_expected_vid(*tr, ty_var_root)) + } + + pub(in super::super) fn type_var_is_sized(&self, self_ty: ty::TyVid) -> bool { + self.obligations_for_self_ty(self_ty) + .any(|(tr, _)| Some(tr.def_id()) == self.tcx.lang_items().sized_trait()) + } + + pub(in super::super) fn err_args(&self, len: usize) -> Vec> { + vec![self.tcx.ty_error(); len] + } + + /// Unifies the output type with the expected type early, for more coercions + /// and forward type information on the input expressions. + #[instrument(skip(self, call_span), level = "debug")] + pub(in super::super) fn expected_inputs_for_expected_output( + &self, + call_span: Span, + expected_ret: Expectation<'tcx>, + formal_ret: Ty<'tcx>, + formal_args: &[Ty<'tcx>], + ) -> Option>> { + let formal_ret = self.resolve_vars_with_obligations(formal_ret); + let ret_ty = expected_ret.only_has_type(self)?; + + // HACK(oli-obk): This is a hack to keep RPIT and TAIT in sync wrt their behaviour. + // Without it, the inference + // variable will get instantiated with the opaque type. The inference variable often + // has various helpful obligations registered for it that help closures figure out their + // signature. If we infer the inference var to the opaque type, the closure won't be able + // to find those obligations anymore, and it can't necessarily find them from the opaque + // type itself. We could be more powerful with inference if we *combined* the obligations + // so that we got both the obligations from the opaque type and the ones from the inference + // variable. That will accept more code than we do right now, so we need to carefully consider + // the implications. + // Note: this check is pessimistic, as the inference type could be matched with something other + // than the opaque type, but then we need a new `TypeRelation` just for this specific case and + // can't re-use `sup` below. + // See src/test/ui/impl-trait/hidden-type-is-opaque.rs and + // src/test/ui/impl-trait/hidden-type-is-opaque-2.rs for examples that hit this path. + if formal_ret.has_infer_types() { + for ty in ret_ty.walk() { + if let ty::subst::GenericArgKind::Type(ty) = ty.unpack() + && let ty::Opaque(def_id, _) = *ty.kind() + && let Some(def_id) = def_id.as_local() + && self.opaque_type_origin(def_id, DUMMY_SP).is_some() { + return None; + } + } + } + + let expect_args = self + .fudge_inference_if_ok(|| { + // Attempt to apply a subtyping relationship between the formal + // return type (likely containing type variables if the function + // is polymorphic) and the expected return type. + // No argument expectations are produced if unification fails. + let origin = self.misc(call_span); + let ures = self.at(&origin, self.param_env).sup(ret_ty, formal_ret); + + // FIXME(#27336) can't use ? here, Try::from_error doesn't default + // to identity so the resulting type is not constrained. + match ures { + Ok(ok) => { + // Process any obligations locally as much as + // we can. We don't care if some things turn + // out unconstrained or ambiguous, as we're + // just trying to get hints here. + let errors = self.save_and_restore_in_snapshot_flag(|_| { + let mut fulfill = >::new(self.tcx); + for obligation in ok.obligations { + fulfill.register_predicate_obligation(self, obligation); + } + fulfill.select_where_possible(self) + }); + + if !errors.is_empty() { + return Err(()); + } + } + Err(_) => return Err(()), + } + + // Record all the argument types, with the substitutions + // produced from the above subtyping unification. + Ok(Some(formal_args.iter().map(|&ty| self.resolve_vars_if_possible(ty)).collect())) + }) + .unwrap_or_default(); + debug!(?formal_args, ?formal_ret, ?expect_args, ?expected_ret); + expect_args + } + + pub(in super::super) fn resolve_lang_item_path( + &self, + lang_item: hir::LangItem, + span: Span, + hir_id: hir::HirId, + expr_hir_id: Option, + ) -> (Res, Ty<'tcx>) { + let def_id = self.tcx.require_lang_item(lang_item, Some(span)); + let def_kind = self.tcx.def_kind(def_id); + + let item_ty = if let DefKind::Variant = def_kind { + self.tcx.bound_type_of(self.tcx.parent(def_id)) + } else { + self.tcx.bound_type_of(def_id) + }; + let substs = self.fresh_substs_for_item(span, def_id); + let ty = item_ty.subst(self.tcx, substs); + + self.write_resolution(hir_id, Ok((def_kind, def_id))); + + let code = match lang_item { + hir::LangItem::IntoFutureIntoFuture => { + Some(ObligationCauseCode::AwaitableExpr(expr_hir_id)) + } + hir::LangItem::IteratorNext | hir::LangItem::IntoIterIntoIter => { + Some(ObligationCauseCode::ForLoopIterator) + } + hir::LangItem::TryTraitFromOutput + | hir::LangItem::TryTraitFromResidual + | hir::LangItem::TryTraitBranch => Some(ObligationCauseCode::QuestionMark), + _ => None, + }; + if let Some(code) = code { + self.add_required_obligations_with_code(span, def_id, substs, move |_, _| code.clone()); + } else { + self.add_required_obligations_for_hir(span, def_id, substs, hir_id); + } + + (Res::Def(def_kind, def_id), ty) + } + + /// Resolves an associated value path into a base type and associated constant, or method + /// resolution. The newly resolved definition is written into `type_dependent_defs`. + pub fn resolve_ty_and_res_fully_qualified_call( + &self, + qpath: &'tcx QPath<'tcx>, + hir_id: hir::HirId, + span: Span, + ) -> (Res, Option>, &'tcx [hir::PathSegment<'tcx>]) { + debug!( + "resolve_ty_and_res_fully_qualified_call: qpath={:?} hir_id={:?} span={:?}", + qpath, hir_id, span + ); + let (ty, qself, item_segment) = match *qpath { + QPath::Resolved(ref opt_qself, ref path) => { + return ( + path.res, + opt_qself.as_ref().map(|qself| self.to_ty(qself)), + path.segments, + ); + } + QPath::TypeRelative(ref qself, ref segment) => { + // Don't use `self.to_ty`, since this will register a WF obligation. + // If we're trying to call a non-existent method on a trait + // (e.g. `MyTrait::missing_method`), then resolution will + // give us a `QPath::TypeRelative` with a trait object as + // `qself`. In that case, we want to avoid registering a WF obligation + // for `dyn MyTrait`, since we don't actually need the trait + // to be object-safe. + // We manually call `register_wf_obligation` in the success path + // below. + (>::ast_ty_to_ty_in_path(self, qself), qself, segment) + } + QPath::LangItem(..) => { + bug!("`resolve_ty_and_res_fully_qualified_call` called on `LangItem`") + } + }; + if let Some(&cached_result) = self.typeck_results.borrow().type_dependent_defs().get(hir_id) + { + self.register_wf_obligation(ty.into(), qself.span, traits::WellFormed(None)); + // Return directly on cache hit. This is useful to avoid doubly reporting + // errors with default match binding modes. See #44614. + let def = cached_result.map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)); + return (def, Some(ty), slice::from_ref(&**item_segment)); + } + let item_name = item_segment.ident; + let result = self + .resolve_fully_qualified_call(span, item_name, ty, qself.span, hir_id) + .or_else(|error| { + let result = match error { + method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)), + _ => Err(ErrorGuaranteed::unchecked_claim_error_was_emitted()), + }; + + // If we have a path like `MyTrait::missing_method`, then don't register + // a WF obligation for `dyn MyTrait` when method lookup fails. Otherwise, + // register a WF obligation so that we can detect any additional + // errors in the self type. + if !(matches!(error, method::MethodError::NoMatch(_)) && ty.is_trait()) { + self.register_wf_obligation(ty.into(), qself.span, traits::WellFormed(None)); + } + if item_name.name != kw::Empty { + if let Some(mut e) = self.report_method_error( + span, + ty, + item_name, + SelfSource::QPath(qself), + error, + None, + ) { + e.emit(); + } + } + result + }); + + if result.is_ok() { + self.register_wf_obligation(ty.into(), qself.span, traits::WellFormed(None)); + } + + // Write back the new resolution. + self.write_resolution(hir_id, result); + ( + result.map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)), + Some(ty), + slice::from_ref(&**item_segment), + ) + } + + /// Given a function `Node`, return its `FnDecl` if it exists, or `None` otherwise. + pub(in super::super) fn get_node_fn_decl( + &self, + node: Node<'tcx>, + ) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident, bool)> { + match node { + Node::Item(&hir::Item { ident, kind: hir::ItemKind::Fn(ref sig, ..), .. }) => { + // This is less than ideal, it will not suggest a return type span on any + // method called `main`, regardless of whether it is actually the entry point, + // but it will still present it as the reason for the expected type. + Some((&sig.decl, ident, ident.name != sym::main)) + } + Node::TraitItem(&hir::TraitItem { + ident, + kind: hir::TraitItemKind::Fn(ref sig, ..), + .. + }) => Some((&sig.decl, ident, true)), + Node::ImplItem(&hir::ImplItem { + ident, + kind: hir::ImplItemKind::Fn(ref sig, ..), + .. + }) => Some((&sig.decl, ident, false)), + _ => None, + } + } + + /// Given a `HirId`, return the `FnDecl` of the method it is enclosed by and whether a + /// suggestion can be made, `None` otherwise. + pub fn get_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, bool)> { + // Get enclosing Fn, if it is a function or a trait method, unless there's a `loop` or + // `while` before reaching it, as block tail returns are not available in them. + self.tcx.hir().get_return_block(blk_id).and_then(|blk_id| { + let parent = self.tcx.hir().get(blk_id); + self.get_node_fn_decl(parent).map(|(fn_decl, _, is_main)| (fn_decl, is_main)) + }) + } + + pub(in super::super) fn note_internal_mutation_in_method( + &self, + err: &mut Diagnostic, + expr: &hir::Expr<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + ) { + if found != self.tcx.types.unit { + return; + } + if let ExprKind::MethodCall(path_segment, rcvr, ..) = expr.kind { + if self + .typeck_results + .borrow() + .expr_ty_adjusted_opt(rcvr) + .map_or(true, |ty| expected.peel_refs() != ty.peel_refs()) + { + return; + } + let mut sp = MultiSpan::from_span(path_segment.ident.span); + sp.push_span_label( + path_segment.ident.span, + format!( + "this call modifies {} in-place", + match rcvr.kind { + ExprKind::Path(QPath::Resolved( + None, + hir::Path { segments: [segment], .. }, + )) => format!("`{}`", segment.ident), + _ => "its receiver".to_string(), + } + ), + ); + sp.push_span_label( + rcvr.span, + "you probably want to use this value after calling the method...", + ); + err.span_note( + sp, + &format!("method `{}` modifies its receiver in-place", path_segment.ident), + ); + err.note(&format!("...instead of the `()` output of method `{}`", path_segment.ident)); + } + } + + pub(in super::super) fn note_need_for_fn_pointer( + &self, + err: &mut Diagnostic, + expected: Ty<'tcx>, + found: Ty<'tcx>, + ) { + let (sig, did, substs) = match (&expected.kind(), &found.kind()) { + (ty::FnDef(did1, substs1), ty::FnDef(did2, substs2)) => { + let sig1 = self.tcx.bound_fn_sig(*did1).subst(self.tcx, substs1); + let sig2 = self.tcx.bound_fn_sig(*did2).subst(self.tcx, substs2); + if sig1 != sig2 { + return; + } + err.note( + "different `fn` items always have unique types, even if their signatures are \ + the same", + ); + (sig1, *did1, substs1) + } + (ty::FnDef(did, substs), ty::FnPtr(sig2)) => { + let sig1 = self.tcx.bound_fn_sig(*did).subst(self.tcx, substs); + if sig1 != *sig2 { + return; + } + (sig1, *did, substs) + } + _ => return, + }; + err.help(&format!("change the expected type to be function pointer `{}`", sig)); + err.help(&format!( + "if the expected type is due to type inference, cast the expected `fn` to a function \ + pointer: `{} as {}`", + self.tcx.def_path_str_with_substs(did, substs), + sig + )); + } + + // Instantiates the given path, which must refer to an item with the given + // number of type parameters and type. + #[instrument(skip(self, span), level = "debug")] + pub fn instantiate_value_path( + &self, + segments: &[hir::PathSegment<'_>], + self_ty: Option>, + res: Res, + span: Span, + hir_id: hir::HirId, + ) -> (Ty<'tcx>, Res) { + let tcx = self.tcx; + + let path_segs = match res { + Res::Local(_) | Res::SelfCtor(_) => vec![], + Res::Def(kind, def_id) => >::def_ids_for_value_path_segments( + self, segments, self_ty, kind, def_id, + ), + _ => bug!("instantiate_value_path on {:?}", res), + }; + + let mut user_self_ty = None; + let mut is_alias_variant_ctor = false; + match res { + Res::Def(DefKind::Ctor(CtorOf::Variant, _), _) + if let Some(self_ty) = self_ty => + { + let adt_def = self_ty.ty_adt_def().unwrap(); + user_self_ty = Some(UserSelfTy { impl_def_id: adt_def.did(), self_ty }); + is_alias_variant_ctor = true; + } + Res::Def(DefKind::AssocFn | DefKind::AssocConst, def_id) => { + let assoc_item = tcx.associated_item(def_id); + let container = assoc_item.container; + let container_id = assoc_item.container_id(tcx); + debug!(?def_id, ?container, ?container_id); + match container { + ty::TraitContainer => { + callee::check_legal_trait_for_method_call(tcx, span, None, span, container_id) + } + ty::ImplContainer => { + if segments.len() == 1 { + // `::assoc` will end up here, and so + // can `T::assoc`. It this came from an + // inherent impl, we need to record the + // `T` for posterity (see `UserSelfTy` for + // details). + let self_ty = self_ty.expect("UFCS sugared assoc missing Self"); + user_self_ty = Some(UserSelfTy { impl_def_id: container_id, self_ty }); + } + } + } + } + _ => {} + } + + // Now that we have categorized what space the parameters for each + // segment belong to, let's sort out the parameters that the user + // provided (if any) into their appropriate spaces. We'll also report + // errors if type parameters are provided in an inappropriate place. + + let generic_segs: FxHashSet<_> = path_segs.iter().map(|PathSeg(_, index)| index).collect(); + let generics_has_err = >::prohibit_generics( + self, + segments.iter().enumerate().filter_map(|(index, seg)| { + if !generic_segs.contains(&index) || is_alias_variant_ctor { + Some(seg) + } else { + None + } + }), + |_| {}, + ); + + if let Res::Local(hid) = res { + let ty = self.local_ty(span, hid).decl_ty; + let ty = self.normalize_associated_types_in(span, ty); + self.write_ty(hir_id, ty); + return (ty, res); + } + + if generics_has_err { + // Don't try to infer type parameters when prohibited generic arguments were given. + user_self_ty = None; + } + + // Now we have to compare the types that the user *actually* + // provided against the types that were *expected*. If the user + // did not provide any types, then we want to substitute inference + // variables. If the user provided some types, we may still need + // to add defaults. If the user provided *too many* types, that's + // a problem. + + let mut infer_args_for_err = FxHashSet::default(); + + let mut explicit_late_bound = ExplicitLateBound::No; + for &PathSeg(def_id, index) in &path_segs { + let seg = &segments[index]; + let generics = tcx.generics_of(def_id); + + // Argument-position `impl Trait` is treated as a normal generic + // parameter internally, but we don't allow users to specify the + // parameter's value explicitly, so we have to do some error- + // checking here. + let arg_count = >::check_generic_arg_count_for_call( + tcx, + span, + def_id, + &generics, + seg, + IsMethodCall::No, + ); + + if let ExplicitLateBound::Yes = arg_count.explicit_late_bound { + explicit_late_bound = ExplicitLateBound::Yes; + } + + if let Err(GenericArgCountMismatch { reported: Some(_), .. }) = arg_count.correct { + infer_args_for_err.insert(index); + self.set_tainted_by_errors(); // See issue #53251. + } + } + + let has_self = path_segs + .last() + .map(|PathSeg(def_id, _)| tcx.generics_of(*def_id).has_self) + .unwrap_or(false); + + let (res, self_ctor_substs) = if let Res::SelfCtor(impl_def_id) = res { + let ty = self.normalize_ty(span, tcx.at(span).type_of(impl_def_id)); + match *ty.kind() { + ty::Adt(adt_def, substs) if adt_def.has_ctor() => { + let variant = adt_def.non_enum_variant(); + let ctor_def_id = variant.ctor_def_id.unwrap(); + ( + Res::Def(DefKind::Ctor(CtorOf::Struct, variant.ctor_kind), ctor_def_id), + Some(substs), + ) + } + _ => { + let mut err = tcx.sess.struct_span_err( + span, + "the `Self` constructor can only be used with tuple or unit structs", + ); + if let Some(adt_def) = ty.ty_adt_def() { + match adt_def.adt_kind() { + AdtKind::Enum => { + err.help("did you mean to use one of the enum's variants?"); + } + AdtKind::Struct | AdtKind::Union => { + err.span_suggestion( + span, + "use curly brackets", + "Self { /* fields */ }", + Applicability::HasPlaceholders, + ); + } + } + } + err.emit(); + + return (tcx.ty_error(), res); + } + } + } else { + (res, None) + }; + let def_id = res.def_id(); + + // The things we are substituting into the type should not contain + // escaping late-bound regions, and nor should the base type scheme. + let ty = tcx.type_of(def_id); + + let arg_count = GenericArgCountResult { + explicit_late_bound, + correct: if infer_args_for_err.is_empty() { + Ok(()) + } else { + Err(GenericArgCountMismatch::default()) + }, + }; + + struct CreateCtorSubstsContext<'a, 'tcx> { + fcx: &'a FnCtxt<'a, 'tcx>, + span: Span, + path_segs: &'a [PathSeg], + infer_args_for_err: &'a FxHashSet, + segments: &'a [hir::PathSegment<'a>], + } + impl<'tcx, 'a> CreateSubstsForGenericArgsCtxt<'a, 'tcx> for CreateCtorSubstsContext<'a, 'tcx> { + fn args_for_def_id( + &mut self, + def_id: DefId, + ) -> (Option<&'a hir::GenericArgs<'a>>, bool) { + if let Some(&PathSeg(_, index)) = + self.path_segs.iter().find(|&PathSeg(did, _)| *did == def_id) + { + // If we've encountered an `impl Trait`-related error, we're just + // going to infer the arguments for better error messages. + if !self.infer_args_for_err.contains(&index) { + // Check whether the user has provided generic arguments. + if let Some(ref data) = self.segments[index].args { + return (Some(data), self.segments[index].infer_args); + } + } + return (None, self.segments[index].infer_args); + } + + (None, true) + } + + fn provided_kind( + &mut self, + param: &ty::GenericParamDef, + arg: &GenericArg<'_>, + ) -> ty::GenericArg<'tcx> { + match (¶m.kind, arg) { + (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => { + >::ast_region_to_region(self.fcx, lt, Some(param)).into() + } + (GenericParamDefKind::Type { .. }, GenericArg::Type(ty)) => { + self.fcx.to_ty(ty).into() + } + (GenericParamDefKind::Const { .. }, GenericArg::Const(ct)) => { + self.fcx.const_arg_to_const(&ct.value, param.def_id).into() + } + (GenericParamDefKind::Type { .. }, GenericArg::Infer(inf)) => { + self.fcx.ty_infer(Some(param), inf.span).into() + } + (GenericParamDefKind::Const { .. }, GenericArg::Infer(inf)) => { + let tcx = self.fcx.tcx(); + self.fcx.ct_infer(tcx.type_of(param.def_id), Some(param), inf.span).into() + } + _ => unreachable!(), + } + } + + fn inferred_kind( + &mut self, + substs: Option<&[ty::GenericArg<'tcx>]>, + param: &ty::GenericParamDef, + infer_args: bool, + ) -> ty::GenericArg<'tcx> { + let tcx = self.fcx.tcx(); + match param.kind { + GenericParamDefKind::Lifetime => { + self.fcx.re_infer(Some(param), self.span).unwrap().into() + } + GenericParamDefKind::Type { has_default, .. } => { + if !infer_args && has_default { + // If we have a default, then we it doesn't matter that we're not + // inferring the type arguments: we provide the default where any + // is missing. + let default = tcx.bound_type_of(param.def_id); + self.fcx + .normalize_ty(self.span, default.subst(tcx, substs.unwrap())) + .into() + } else { + // If no type arguments were provided, we have to infer them. + // This case also occurs as a result of some malformed input, e.g. + // a lifetime argument being given instead of a type parameter. + // Using inference instead of `Error` gives better error messages. + self.fcx.var_for_def(self.span, param) + } + } + GenericParamDefKind::Const { has_default } => { + if !infer_args && has_default { + tcx.bound_const_param_default(param.def_id) + .subst(tcx, substs.unwrap()) + .into() + } else { + self.fcx.var_for_def(self.span, param) + } + } + } + } + } + + let substs = self_ctor_substs.unwrap_or_else(|| { + >::create_substs_for_generic_args( + tcx, + def_id, + &[], + has_self, + self_ty, + &arg_count, + &mut CreateCtorSubstsContext { + fcx: self, + span, + path_segs: &path_segs, + infer_args_for_err: &infer_args_for_err, + segments, + }, + ) + }); + assert!(!substs.has_escaping_bound_vars()); + assert!(!ty.has_escaping_bound_vars()); + + // First, store the "user substs" for later. + self.write_user_type_annotation_from_substs(hir_id, def_id, substs, user_self_ty); + + self.add_required_obligations_for_hir(span, def_id, &substs, hir_id); + + // Substitute the values for the type parameters into the type of + // the referenced item. + let ty_substituted = self.instantiate_type_scheme(span, &substs, ty); + + if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty { + // In the case of `Foo::method` and `>::method`, if `method` + // is inherent, there is no `Self` parameter; instead, the impl needs + // type parameters, which we can infer by unifying the provided `Self` + // with the substituted impl type. + // This also occurs for an enum variant on a type alias. + let ty = tcx.type_of(impl_def_id); + + let impl_ty = self.instantiate_type_scheme(span, &substs, ty); + match self.at(&self.misc(span), self.param_env).eq(impl_ty, self_ty) { + Ok(ok) => self.register_infer_ok_obligations(ok), + Err(_) => { + self.tcx.sess.delay_span_bug( + span, + &format!( + "instantiate_value_path: (UFCS) {:?} was a subtype of {:?} but now is not?", + self_ty, + impl_ty, + ), + ); + } + } + } + + debug!("instantiate_value_path: type of {:?} is {:?}", hir_id, ty_substituted); + self.write_substs(hir_id, substs); + + (ty_substituted, res) + } + + /// Add all the obligations that are required, substituting and normalized appropriately. + pub(crate) fn add_required_obligations_for_hir( + &self, + span: Span, + def_id: DefId, + substs: SubstsRef<'tcx>, + hir_id: hir::HirId, + ) { + self.add_required_obligations_with_code(span, def_id, substs, |idx, span| { + if span.is_dummy() { + ObligationCauseCode::ExprItemObligation(def_id, hir_id, idx) + } else { + ObligationCauseCode::ExprBindingObligation(def_id, span, hir_id, idx) + } + }) + } + + #[instrument(level = "debug", skip(self, code, span, substs))] + fn add_required_obligations_with_code( + &self, + span: Span, + def_id: DefId, + substs: SubstsRef<'tcx>, + code: impl Fn(usize, Span) -> ObligationCauseCode<'tcx>, + ) { + let param_env = self.param_env; + + let remap = match self.tcx.def_kind(def_id) { + // Associated consts have `Self: ~const Trait` bounds that should be satisfiable when + // `Self: Trait` is satisfied because it does not matter whether the impl is `const`. + // Therefore we have to remap the param env here to be non-const. + hir::def::DefKind::AssocConst => true, + hir::def::DefKind::AssocFn + if self.tcx.def_kind(self.tcx.parent(def_id)) == hir::def::DefKind::Trait => + { + // N.B.: All callsites to this function involve checking a path expression. + // + // When instantiating a trait method as a function item, it does not actually matter whether + // the trait is `const` or not, or whether `where T: ~const Tr` needs to be satisfied as + // `const`. If we were to introduce instantiating trait methods as `const fn`s, we would + // check that after this, either via a bound `where F: ~const FnOnce` or when coercing to a + // `const fn` pointer. + // + // FIXME(fee1-dead) FIXME(const_trait_impl): update this doc when trait methods can satisfy + // `~const FnOnce` or can be coerced to `const fn` pointer. + true + } + _ => false, + }; + let (bounds, _) = self.instantiate_bounds(span, def_id, &substs); + + for mut obligation in traits::predicates_for_generics( + |idx, predicate_span| { + traits::ObligationCause::new(span, self.body_id, code(idx, predicate_span)) + }, + param_env, + bounds, + ) { + if remap { + obligation = obligation.without_const(self.tcx); + } + self.register_predicate(obligation); + } + } + + /// Resolves `typ` by a single level if `typ` is a type variable. + /// If no resolution is possible, then an error is reported. + /// Numeric inference variables may be left unresolved. + pub fn structurally_resolved_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> { + let ty = self.resolve_vars_with_obligations(ty); + if !ty.is_ty_var() { + ty + } else { + if !self.is_tainted_by_errors() { + self.err_ctxt() + .emit_inference_failure_err((**self).body_id, sp, ty.into(), E0282, true) + .emit(); + } + let err = self.tcx.ty_error(); + self.demand_suptype(sp, err, ty); + err + } + } + + pub(in super::super) fn with_breakable_ctxt R, R>( + &self, + id: hir::HirId, + ctxt: BreakableCtxt<'tcx>, + f: F, + ) -> (BreakableCtxt<'tcx>, R) { + let index; + { + let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); + index = enclosing_breakables.stack.len(); + enclosing_breakables.by_id.insert(id, index); + enclosing_breakables.stack.push(ctxt); + } + let result = f(); + let ctxt = { + let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); + debug_assert!(enclosing_breakables.stack.len() == index + 1); + enclosing_breakables.by_id.remove(&id).expect("missing breakable context"); + enclosing_breakables.stack.pop().expect("missing breakable context") + }; + (ctxt, result) + } + + /// Instantiate a QueryResponse in a probe context, without a + /// good ObligationCause. + pub(in super::super) fn probe_instantiate_query_response( + &self, + span: Span, + original_values: &OriginalQueryValues<'tcx>, + query_result: &Canonical<'tcx, QueryResponse<'tcx, Ty<'tcx>>>, + ) -> InferResult<'tcx, Ty<'tcx>> { + self.instantiate_query_response_and_region_obligations( + &traits::ObligationCause::misc(span, self.body_id), + self.param_env, + original_values, + query_result, + ) + } + + /// Returns `true` if an expression is contained inside the LHS of an assignment expression. + pub(in super::super) fn expr_in_place(&self, mut expr_id: hir::HirId) -> bool { + let mut contained_in_place = false; + + while let hir::Node::Expr(parent_expr) = + self.tcx.hir().get(self.tcx.hir().get_parent_node(expr_id)) + { + match &parent_expr.kind { + hir::ExprKind::Assign(lhs, ..) | hir::ExprKind::AssignOp(_, lhs, ..) => { + if lhs.hir_id == expr_id { + contained_in_place = true; + break; + } + } + _ => (), + } + expr_id = parent_expr.hir_id; + } + + contained_in_place + } +} diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/arg_matrix.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/arg_matrix.rs new file mode 100644 index 000000000..fc83994ca --- /dev/null +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/arg_matrix.rs @@ -0,0 +1,383 @@ +use std::cmp; + +use rustc_index::vec::IndexVec; +use rustc_middle::ty::error::TypeError; + +rustc_index::newtype_index! { + pub(crate) struct ExpectedIdx { + DEBUG_FORMAT = "ExpectedIdx({})", + } +} + +rustc_index::newtype_index! { + pub(crate) struct ProvidedIdx { + DEBUG_FORMAT = "ProvidedIdx({})", + } +} + +impl ExpectedIdx { + pub fn to_provided_idx(self) -> ProvidedIdx { + ProvidedIdx::from_usize(self.as_usize()) + } +} + +// An issue that might be found in the compatibility matrix +#[derive(Debug)] +enum Issue { + /// The given argument is the invalid type for the input + Invalid(usize), + /// There is a missing input + Missing(usize), + /// There's a superfluous argument + Extra(usize), + /// Two arguments should be swapped + Swap(usize, usize), + /// Several arguments should be reordered + Permutation(Vec>), +} + +#[derive(Clone, Debug)] +pub(crate) enum Compatibility<'tcx> { + Compatible, + Incompatible(Option>), +} + +/// Similar to `Issue`, but contains some extra information +#[derive(Debug)] +pub(crate) enum Error<'tcx> { + /// The provided argument is the invalid type for the expected input + Invalid(ProvidedIdx, ExpectedIdx, Compatibility<'tcx>), + /// There is a missing input + Missing(ExpectedIdx), + /// There's a superfluous argument + Extra(ProvidedIdx), + /// Two arguments should be swapped + Swap(ProvidedIdx, ProvidedIdx, ExpectedIdx, ExpectedIdx), + /// Several arguments should be reordered + Permutation(Vec<(ExpectedIdx, ProvidedIdx)>), +} + +pub(crate) struct ArgMatrix<'tcx> { + /// Maps the indices in the `compatibility_matrix` rows to the indices of + /// the *user provided* inputs + provided_indices: Vec, + /// Maps the indices in the `compatibility_matrix` columns to the indices + /// of the *expected* args + expected_indices: Vec, + /// The first dimension (rows) are the remaining user provided inputs to + /// match and the second dimension (cols) are the remaining expected args + /// to match + compatibility_matrix: Vec>>, +} + +impl<'tcx> ArgMatrix<'tcx> { + pub(crate) fn new Compatibility<'tcx>>( + provided_count: usize, + expected_input_count: usize, + mut is_compatible: F, + ) -> Self { + let compatibility_matrix = (0..provided_count) + .map(|i| { + (0..expected_input_count) + .map(|j| is_compatible(ProvidedIdx::from_usize(i), ExpectedIdx::from_usize(j))) + .collect() + }) + .collect(); + ArgMatrix { + provided_indices: (0..provided_count).map(ProvidedIdx::from_usize).collect(), + expected_indices: (0..expected_input_count).map(ExpectedIdx::from_usize).collect(), + compatibility_matrix, + } + } + + /// Remove a given input from consideration + fn eliminate_provided(&mut self, idx: usize) { + self.provided_indices.remove(idx); + self.compatibility_matrix.remove(idx); + } + + /// Remove a given argument from consideration + fn eliminate_expected(&mut self, idx: usize) { + self.expected_indices.remove(idx); + for row in &mut self.compatibility_matrix { + row.remove(idx); + } + } + + /// "satisfy" an input with a given arg, removing both from consideration + fn satisfy_input(&mut self, provided_idx: usize, expected_idx: usize) { + self.eliminate_provided(provided_idx); + self.eliminate_expected(expected_idx); + } + + // Returns a `Vec` of (user input, expected arg) of matched arguments. These + // are inputs on the remaining diagonal that match. + fn eliminate_satisfied(&mut self) -> Vec<(ProvidedIdx, ExpectedIdx)> { + let num_args = cmp::min(self.provided_indices.len(), self.expected_indices.len()); + let mut eliminated = vec![]; + for i in (0..num_args).rev() { + if matches!(self.compatibility_matrix[i][i], Compatibility::Compatible) { + eliminated.push((self.provided_indices[i], self.expected_indices[i])); + self.satisfy_input(i, i); + } + } + eliminated + } + + // Find some issue in the compatibility matrix + fn find_issue(&self) -> Option { + let mat = &self.compatibility_matrix; + let ai = &self.expected_indices; + let ii = &self.provided_indices; + + // Issue: 100478, when we end the iteration, + // `next_unmatched_idx` will point to the index of the first unmatched + let mut next_unmatched_idx = 0; + for i in 0..cmp::max(ai.len(), ii.len()) { + // If we eliminate the last row, any left-over arguments are considered missing + if i >= mat.len() { + return Some(Issue::Missing(next_unmatched_idx)); + } + // If we eliminate the last column, any left-over inputs are extra + if mat[i].len() == 0 { + return Some(Issue::Extra(next_unmatched_idx)); + } + + // Make sure we don't pass the bounds of our matrix + let is_arg = i < ai.len(); + let is_input = i < ii.len(); + if is_arg && is_input && matches!(mat[i][i], Compatibility::Compatible) { + // This is a satisfied input, so move along + next_unmatched_idx += 1; + continue; + } + + let mut useless = true; + let mut unsatisfiable = true; + if is_arg { + for j in 0..ii.len() { + // If we find at least one input this argument could satisfy + // this argument isn't unsatisfiable + if matches!(mat[j][i], Compatibility::Compatible) { + unsatisfiable = false; + break; + } + } + } + if is_input { + for j in 0..ai.len() { + // If we find at least one argument that could satisfy this input + // this input isn't useless + if matches!(mat[i][j], Compatibility::Compatible) { + useless = false; + break; + } + } + } + + match (is_input, is_arg, useless, unsatisfiable) { + // If an argument is unsatisfied, and the input in its position is useless + // then the most likely explanation is that we just got the types wrong + (true, true, true, true) => return Some(Issue::Invalid(i)), + // Otherwise, if an input is useless, then indicate that this is an extra argument + (true, _, true, _) => return Some(Issue::Extra(i)), + // Otherwise, if an argument is unsatisfiable, indicate that it's missing + (_, true, _, true) => return Some(Issue::Missing(i)), + (true, true, _, _) => { + // The argument isn't useless, and the input isn't unsatisfied, + // so look for a parameter we might swap it with + // We look for swaps explicitly, instead of just falling back on permutations + // so that cases like (A,B,C,D) given (B,A,D,C) show up as two swaps, + // instead of a large permutation of 4 elements. + for j in 0..cmp::min(ai.len(), ii.len()) { + if i == j || matches!(mat[j][j], Compatibility::Compatible) { + continue; + } + if matches!(mat[i][j], Compatibility::Compatible) + && matches!(mat[j][i], Compatibility::Compatible) + { + return Some(Issue::Swap(i, j)); + } + } + } + _ => { + continue; + } + } + } + + // We didn't find any of the individual issues above, but + // there might be a larger permutation of parameters, so we now check for that + // by checking for cycles + // We use a double option at position i in this vec to represent: + // - None: We haven't computed anything about this argument yet + // - Some(None): This argument definitely doesn't participate in a cycle + // - Some(Some(x)): the i-th argument could permute to the x-th position + let mut permutation: Vec>> = vec![None; mat.len()]; + let mut permutation_found = false; + for i in 0..mat.len() { + if permutation[i].is_some() { + // We've already decided whether this argument is or is not in a loop + continue; + } + + let mut stack = vec![]; + let mut j = i; + let mut last = i; + let mut is_cycle = true; + loop { + stack.push(j); + // Look for params this one could slot into + let compat: Vec<_> = + mat[j] + .iter() + .enumerate() + .filter_map(|(i, c)| { + if matches!(c, Compatibility::Compatible) { Some(i) } else { None } + }) + .collect(); + if compat.len() < 1 { + // try to find a cycle even when this could go into multiple slots, see #101097 + is_cycle = false; + break; + } + j = compat[0]; + if stack.contains(&j) { + last = j; + break; + } + } + if stack.len() <= 2 { + // If we encounter a cycle of 1 or 2 elements, we'll let the + // "satisfy" and "swap" code above handle those + is_cycle = false; + } + // We've built up some chain, some of which might be a cycle + // ex: [1,2,3,4]; last = 2; j = 2; + // So, we want to mark 4, 3, and 2 as part of a permutation + permutation_found = is_cycle; + while let Some(x) = stack.pop() { + if is_cycle { + permutation[x] = Some(Some(j)); + j = x; + if j == last { + // From here on out, we're a tail leading into a cycle, + // not the cycle itself + is_cycle = false; + } + } else { + // Some(None) ensures we save time by skipping this argument again + permutation[x] = Some(None); + } + } + } + + if permutation_found { + // Map unwrap to remove the first layer of Some + let final_permutation: Vec> = + permutation.into_iter().map(|x| x.unwrap()).collect(); + return Some(Issue::Permutation(final_permutation)); + } + return None; + } + + // Obviously, detecting exact user intention is impossible, so the goal here is to + // come up with as likely of a story as we can to be helpful. + // + // We'll iteratively removed "satisfied" input/argument pairs, + // then check for the cases above, until we've eliminated the entire grid + // + // We'll want to know which arguments and inputs these rows and columns correspond to + // even after we delete them. + pub(crate) fn find_errors( + mut self, + ) -> (Vec>, IndexVec>) { + let provided_arg_count = self.provided_indices.len(); + + let mut errors: Vec> = vec![]; + // For each expected argument, the matched *actual* input + let mut matched_inputs: IndexVec> = + IndexVec::from_elem_n(None, self.expected_indices.len()); + + // Before we start looking for issues, eliminate any arguments that are already satisfied, + // so that an argument which is already spoken for by the input it's in doesn't + // spill over into another similarly typed input + // ex: + // fn some_func(_a: i32, _b: i32) {} + // some_func(1, ""); + // Without this elimination, the first argument causes the second argument + // to show up as both a missing input and extra argument, rather than + // just an invalid type. + for (provided, expected) in self.eliminate_satisfied() { + matched_inputs[expected] = Some(provided); + } + + while !self.provided_indices.is_empty() || !self.expected_indices.is_empty() { + let res = self.find_issue(); + match res { + Some(Issue::Invalid(idx)) => { + let compatibility = self.compatibility_matrix[idx][idx].clone(); + let input_idx = self.provided_indices[idx]; + let arg_idx = self.expected_indices[idx]; + self.satisfy_input(idx, idx); + errors.push(Error::Invalid(input_idx, arg_idx, compatibility)); + } + Some(Issue::Extra(idx)) => { + let input_idx = self.provided_indices[idx]; + self.eliminate_provided(idx); + errors.push(Error::Extra(input_idx)); + } + Some(Issue::Missing(idx)) => { + let arg_idx = self.expected_indices[idx]; + self.eliminate_expected(idx); + errors.push(Error::Missing(arg_idx)); + } + Some(Issue::Swap(idx, other)) => { + let input_idx = self.provided_indices[idx]; + let other_input_idx = self.provided_indices[other]; + let arg_idx = self.expected_indices[idx]; + let other_arg_idx = self.expected_indices[other]; + let (min, max) = (cmp::min(idx, other), cmp::max(idx, other)); + self.satisfy_input(min, max); + // Subtract 1 because we already removed the "min" row + self.satisfy_input(max - 1, min); + errors.push(Error::Swap(input_idx, other_input_idx, arg_idx, other_arg_idx)); + matched_inputs[other_arg_idx] = Some(input_idx); + matched_inputs[arg_idx] = Some(other_input_idx); + } + Some(Issue::Permutation(args)) => { + let mut idxs: Vec = args.iter().filter_map(|&a| a).collect(); + + let mut real_idxs: IndexVec> = + IndexVec::from_elem_n(None, provided_arg_count); + for (src, dst) in + args.iter().enumerate().filter_map(|(src, dst)| dst.map(|dst| (src, dst))) + { + let src_input_idx = self.provided_indices[src]; + let dst_input_idx = self.provided_indices[dst]; + let dest_arg_idx = self.expected_indices[dst]; + real_idxs[src_input_idx] = Some((dest_arg_idx, dst_input_idx)); + matched_inputs[dest_arg_idx] = Some(src_input_idx); + } + idxs.sort(); + idxs.reverse(); + for i in idxs { + self.satisfy_input(i, i); + } + errors.push(Error::Permutation(real_idxs.into_iter().flatten().collect())); + } + None => { + // We didn't find any issues, so we need to push the algorithm forward + // First, eliminate any arguments that currently satisfy their inputs + let eliminated = self.eliminate_satisfied(); + assert!(!eliminated.is_empty(), "didn't eliminated any indice in this round"); + for (inp, arg) in eliminated { + matched_inputs[arg] = Some(inp); + } + } + }; + } + + return (errors, matched_inputs); + } +} diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs new file mode 100644 index 000000000..8e0fcb56c --- /dev/null +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs @@ -0,0 +1,2236 @@ +use crate::coercion::CoerceMany; +use crate::fn_ctxt::arg_matrix::{ArgMatrix, Compatibility, Error, ExpectedIdx, ProvidedIdx}; +use crate::gather_locals::Declaration; +use crate::method::MethodCallee; +use crate::Expectation::*; +use crate::TupleArgumentsFlag::*; +use crate::{ + struct_span_err, BreakableCtxt, Diverges, Expectation, FnCtxt, LocalTy, Needs, + TupleArgumentsFlag, +}; +use rustc_ast as ast; +use rustc_data_structures::fx::FxHashSet; +use rustc_errors::{pluralize, Applicability, Diagnostic, DiagnosticId, MultiSpan}; +use rustc_hir as hir; +use rustc_hir::def::{CtorOf, DefKind, Res}; +use rustc_hir::def_id::DefId; +use rustc_hir::{ExprKind, Node, QPath}; +use rustc_hir_analysis::astconv::AstConv; +use rustc_hir_analysis::check::intrinsicck::InlineAsmCtxt; +use rustc_hir_analysis::check::potentially_plural_count; +use rustc_hir_analysis::structured_errors::StructuredDiagnostic; +use rustc_index::vec::IndexVec; +use rustc_infer::infer::error_reporting::{FailureCode, ObligationCauseExt}; +use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; +use rustc_infer::infer::InferOk; +use rustc_infer::infer::TypeTrace; +use rustc_middle::ty::adjustment::AllowTwoPhase; +use rustc_middle::ty::visit::TypeVisitable; +use rustc_middle::ty::{self, DefIdTree, IsSuggestable, Ty, TypeSuperVisitable, TypeVisitor}; +use rustc_session::Session; +use rustc_span::symbol::Ident; +use rustc_span::{self, sym, Span}; +use rustc_trait_selection::traits::{self, ObligationCauseCode, SelectionContext}; + +use std::iter; +use std::mem; +use std::ops::ControlFlow; +use std::slice; + +impl<'a, 'tcx> FnCtxt<'a, 'tcx> { + pub(in super::super) fn check_casts(&mut self) { + // don't hold the borrow to deferred_cast_checks while checking to avoid borrow checker errors + // when writing to `self.param_env`. + let mut deferred_cast_checks = mem::take(&mut *self.deferred_cast_checks.borrow_mut()); + + debug!("FnCtxt::check_casts: {} deferred checks", deferred_cast_checks.len()); + for cast in deferred_cast_checks.drain(..) { + let prev_env = self.param_env; + self.param_env = self.param_env.with_constness(cast.constness); + + cast.check(self); + + self.param_env = prev_env; + } + + *self.deferred_cast_checks.borrow_mut() = deferred_cast_checks; + } + + pub(in super::super) fn check_transmutes(&self) { + let mut deferred_transmute_checks = self.deferred_transmute_checks.borrow_mut(); + debug!("FnCtxt::check_transmutes: {} deferred checks", deferred_transmute_checks.len()); + for (from, to, hir_id) in deferred_transmute_checks.drain(..) { + self.check_transmute(from, to, hir_id); + } + } + + pub(in super::super) fn check_asms(&self) { + let mut deferred_asm_checks = self.deferred_asm_checks.borrow_mut(); + debug!("FnCtxt::check_asm: {} deferred checks", deferred_asm_checks.len()); + for (asm, hir_id) in deferred_asm_checks.drain(..) { + let enclosing_id = self.tcx.hir().enclosing_body_owner(hir_id); + let get_operand_ty = |expr| { + let ty = self.typeck_results.borrow().expr_ty_adjusted(expr); + let ty = self.resolve_vars_if_possible(ty); + if ty.has_non_region_infer() { + assert!(self.is_tainted_by_errors()); + self.tcx.ty_error() + } else { + self.tcx.erase_regions(ty) + } + }; + InlineAsmCtxt::new_in_fn(self.tcx, self.param_env, get_operand_ty) + .check_asm(asm, self.tcx.hir().local_def_id_to_hir_id(enclosing_id)); + } + } + + pub(in super::super) fn check_method_argument_types( + &self, + sp: Span, + expr: &'tcx hir::Expr<'tcx>, + method: Result, ()>, + args_no_rcvr: &'tcx [hir::Expr<'tcx>], + tuple_arguments: TupleArgumentsFlag, + expected: Expectation<'tcx>, + ) -> Ty<'tcx> { + let has_error = match method { + Ok(method) => method.substs.references_error() || method.sig.references_error(), + Err(_) => true, + }; + if has_error { + let err_inputs = self.err_args(args_no_rcvr.len()); + + let err_inputs = match tuple_arguments { + DontTupleArguments => err_inputs, + TupleArguments => vec![self.tcx.intern_tup(&err_inputs)], + }; + + self.check_argument_types( + sp, + expr, + &err_inputs, + None, + args_no_rcvr, + false, + tuple_arguments, + method.ok().map(|method| method.def_id), + ); + return self.tcx.ty_error(); + } + + let method = method.unwrap(); + // HACK(eddyb) ignore self in the definition (see above). + let expected_input_tys = self.expected_inputs_for_expected_output( + sp, + expected, + method.sig.output(), + &method.sig.inputs()[1..], + ); + self.check_argument_types( + sp, + expr, + &method.sig.inputs()[1..], + expected_input_tys, + args_no_rcvr, + method.sig.c_variadic, + tuple_arguments, + Some(method.def_id), + ); + method.sig.output() + } + + /// Generic function that factors out common logic from function calls, + /// method calls and overloaded operators. + pub(in super::super) fn check_argument_types( + &self, + // Span enclosing the call site + call_span: Span, + // Expression of the call site + call_expr: &'tcx hir::Expr<'tcx>, + // Types (as defined in the *signature* of the target function) + formal_input_tys: &[Ty<'tcx>], + // More specific expected types, after unifying with caller output types + expected_input_tys: Option>>, + // The expressions for each provided argument + provided_args: &'tcx [hir::Expr<'tcx>], + // Whether the function is variadic, for example when imported from C + c_variadic: bool, + // Whether the arguments have been bundled in a tuple (ex: closures) + tuple_arguments: TupleArgumentsFlag, + // The DefId for the function being called, for better error messages + fn_def_id: Option, + ) { + let tcx = self.tcx; + + // Conceptually, we've got some number of expected inputs, and some number of provided arguments + // and we can form a grid of whether each argument could satisfy a given input: + // in1 | in2 | in3 | ... + // arg1 ? | | | + // arg2 | ? | | + // arg3 | | ? | + // ... + // Initially, we just check the diagonal, because in the case of correct code + // these are the only checks that matter + // However, in the unhappy path, we'll fill in this whole grid to attempt to provide + // better error messages about invalid method calls. + + // All the input types from the fn signature must outlive the call + // so as to validate implied bounds. + for (&fn_input_ty, arg_expr) in iter::zip(formal_input_tys, provided_args) { + self.register_wf_obligation(fn_input_ty.into(), arg_expr.span, traits::MiscObligation); + } + + let mut err_code = "E0061"; + + // If the arguments should be wrapped in a tuple (ex: closures), unwrap them here + let (formal_input_tys, expected_input_tys) = if tuple_arguments == TupleArguments { + let tuple_type = self.structurally_resolved_type(call_span, formal_input_tys[0]); + match tuple_type.kind() { + // We expected a tuple and got a tuple + ty::Tuple(arg_types) => { + // Argument length differs + if arg_types.len() != provided_args.len() { + err_code = "E0057"; + } + let expected_input_tys = match expected_input_tys { + Some(expected_input_tys) => match expected_input_tys.get(0) { + Some(ty) => match ty.kind() { + ty::Tuple(tys) => Some(tys.iter().collect()), + _ => None, + }, + None => None, + }, + None => None, + }; + (arg_types.iter().collect(), expected_input_tys) + } + _ => { + // Otherwise, there's a mismatch, so clear out what we're expecting, and set + // our input types to err_args so we don't blow up the error messages + struct_span_err!( + tcx.sess, + call_span, + E0059, + "cannot use call notation; the first type parameter \ + for the function trait is neither a tuple nor unit" + ) + .emit(); + (self.err_args(provided_args.len()), None) + } + } + } else { + (formal_input_tys.to_vec(), expected_input_tys) + }; + + // If there are no external expectations at the call site, just use the types from the function defn + let expected_input_tys = if let Some(expected_input_tys) = expected_input_tys { + assert_eq!(expected_input_tys.len(), formal_input_tys.len()); + expected_input_tys + } else { + formal_input_tys.clone() + }; + + let minimum_input_count = expected_input_tys.len(); + let provided_arg_count = provided_args.len(); + + let is_const_eval_select = matches!(fn_def_id, Some(def_id) if + self.tcx.def_kind(def_id) == hir::def::DefKind::Fn + && self.tcx.is_intrinsic(def_id) + && self.tcx.item_name(def_id) == sym::const_eval_select); + + // We introduce a helper function to demand that a given argument satisfy a given input + // This is more complicated than just checking type equality, as arguments could be coerced + // This version writes those types back so further type checking uses the narrowed types + let demand_compatible = |idx| { + let formal_input_ty: Ty<'tcx> = formal_input_tys[idx]; + let expected_input_ty: Ty<'tcx> = expected_input_tys[idx]; + let provided_arg = &provided_args[idx]; + + debug!("checking argument {}: {:?} = {:?}", idx, provided_arg, formal_input_ty); + + // We're on the happy path here, so we'll do a more involved check and write back types + // To check compatibility, we'll do 3 things: + // 1. Unify the provided argument with the expected type + let expectation = Expectation::rvalue_hint(self, expected_input_ty); + + let checked_ty = self.check_expr_with_expectation(provided_arg, expectation); + + // 2. Coerce to the most detailed type that could be coerced + // to, which is `expected_ty` if `rvalue_hint` returns an + // `ExpectHasType(expected_ty)`, or the `formal_ty` otherwise. + let coerced_ty = expectation.only_has_type(self).unwrap_or(formal_input_ty); + + // Cause selection errors caused by resolving a single argument to point at the + // argument and not the call. This lets us customize the span pointed to in the + // fulfillment error to be more accurate. + let coerced_ty = self.resolve_vars_with_obligations(coerced_ty); + + let coerce_error = self + .try_coerce(provided_arg, checked_ty, coerced_ty, AllowTwoPhase::Yes, None) + .err(); + + if coerce_error.is_some() { + return Compatibility::Incompatible(coerce_error); + } + + // Check that second and third argument of `const_eval_select` must be `FnDef`, and additionally that + // the second argument must be `const fn`. The first argument must be a tuple, but this is already expressed + // in the function signature (`F: FnOnce`), so I did not bother to add another check here. + // + // This check is here because there is currently no way to express a trait bound for `FnDef` types only. + if is_const_eval_select && (1..=2).contains(&idx) { + if let ty::FnDef(def_id, _) = checked_ty.kind() { + if idx == 1 && !self.tcx.is_const_fn_raw(*def_id) { + self.tcx + .sess + .struct_span_err(provided_arg.span, "this argument must be a `const fn`") + .help("consult the documentation on `const_eval_select` for more information") + .emit(); + } + } else { + self.tcx + .sess + .struct_span_err(provided_arg.span, "this argument must be a function item") + .note(format!("expected a function item, found {checked_ty}")) + .help( + "consult the documentation on `const_eval_select` for more information", + ) + .emit(); + } + } + + // 3. Check if the formal type is a supertype of the checked one + // and register any such obligations for future type checks + let supertype_error = self + .at(&self.misc(provided_arg.span), self.param_env) + .sup(formal_input_ty, coerced_ty); + let subtyping_error = match supertype_error { + Ok(InferOk { obligations, value: () }) => { + self.register_predicates(obligations); + None + } + Err(err) => Some(err), + }; + + // If neither check failed, the types are compatible + match subtyping_error { + None => Compatibility::Compatible, + Some(_) => Compatibility::Incompatible(subtyping_error), + } + }; + + // To start, we only care "along the diagonal", where we expect every + // provided arg to be in the right spot + let mut compatibility_diagonal = + vec![Compatibility::Incompatible(None); provided_args.len()]; + + // Keep track of whether we *could possibly* be satisfied, i.e. whether we're on the happy path + // if the wrong number of arguments were supplied, we CAN'T be satisfied, + // and if we're c_variadic, the supplied arguments must be >= the minimum count from the function + // otherwise, they need to be identical, because rust doesn't currently support variadic functions + let mut call_appears_satisfied = if c_variadic { + provided_arg_count >= minimum_input_count + } else { + provided_arg_count == minimum_input_count + }; + + // Check the arguments. + // We do this in a pretty awful way: first we type-check any arguments + // that are not closures, then we type-check the closures. This is so + // that we have more information about the types of arguments when we + // type-check the functions. This isn't really the right way to do this. + for check_closures in [false, true] { + // More awful hacks: before we check argument types, try to do + // an "opportunistic" trait resolution of any trait bounds on + // the call. This helps coercions. + if check_closures { + self.select_obligations_where_possible(false, |_| {}) + } + + // Check each argument, to satisfy the input it was provided for + // Visually, we're traveling down the diagonal of the compatibility matrix + for (idx, arg) in provided_args.iter().enumerate() { + // Warn only for the first loop (the "no closures" one). + // Closure arguments themselves can't be diverging, but + // a previous argument can, e.g., `foo(panic!(), || {})`. + if !check_closures { + self.warn_if_unreachable(arg.hir_id, arg.span, "expression"); + } + + // For C-variadic functions, we don't have a declared type for all of + // the arguments hence we only do our usual type checking with + // the arguments who's types we do know. However, we *can* check + // for unreachable expressions (see above). + // FIXME: unreachable warning current isn't emitted + if idx >= minimum_input_count { + continue; + } + + let is_closure = matches!(arg.kind, ExprKind::Closure { .. }); + if is_closure != check_closures { + continue; + } + + let compatible = demand_compatible(idx); + let is_compatible = matches!(compatible, Compatibility::Compatible); + compatibility_diagonal[idx] = compatible; + + if !is_compatible { + call_appears_satisfied = false; + } + } + } + + if c_variadic && provided_arg_count < minimum_input_count { + err_code = "E0060"; + } + + for arg in provided_args.iter().skip(minimum_input_count) { + // Make sure we've checked this expr at least once. + let arg_ty = self.check_expr(&arg); + + // If the function is c-style variadic, we skipped a bunch of arguments + // so we need to check those, and write out the types + // Ideally this would be folded into the above, for uniform style + // but c-variadic is already a corner case + if c_variadic { + fn variadic_error<'tcx>( + sess: &'tcx Session, + span: Span, + ty: Ty<'tcx>, + cast_ty: &str, + ) { + use rustc_hir_analysis::structured_errors::MissingCastForVariadicArg; + + MissingCastForVariadicArg { sess, span, ty, cast_ty }.diagnostic().emit(); + } + + // There are a few types which get autopromoted when passed via varargs + // in C but we just error out instead and require explicit casts. + let arg_ty = self.structurally_resolved_type(arg.span, arg_ty); + match arg_ty.kind() { + ty::Float(ty::FloatTy::F32) => { + variadic_error(tcx.sess, arg.span, arg_ty, "c_double"); + } + ty::Int(ty::IntTy::I8 | ty::IntTy::I16) | ty::Bool => { + variadic_error(tcx.sess, arg.span, arg_ty, "c_int"); + } + ty::Uint(ty::UintTy::U8 | ty::UintTy::U16) => { + variadic_error(tcx.sess, arg.span, arg_ty, "c_uint"); + } + ty::FnDef(..) => { + let ptr_ty = self.tcx.mk_fn_ptr(arg_ty.fn_sig(self.tcx)); + let ptr_ty = self.resolve_vars_if_possible(ptr_ty); + variadic_error(tcx.sess, arg.span, arg_ty, &ptr_ty.to_string()); + } + _ => {} + } + } + } + + if !call_appears_satisfied { + let compatibility_diagonal = IndexVec::from_raw(compatibility_diagonal); + let provided_args = IndexVec::from_iter(provided_args.iter().take(if c_variadic { + minimum_input_count + } else { + provided_arg_count + })); + debug_assert_eq!( + formal_input_tys.len(), + expected_input_tys.len(), + "expected formal_input_tys to be the same size as expected_input_tys" + ); + let formal_and_expected_inputs = IndexVec::from_iter( + formal_input_tys + .iter() + .copied() + .zip(expected_input_tys.iter().copied()) + .map(|vars| self.resolve_vars_if_possible(vars)), + ); + + self.report_arg_errors( + compatibility_diagonal, + formal_and_expected_inputs, + provided_args, + c_variadic, + err_code, + fn_def_id, + call_span, + call_expr, + ); + } + } + + fn report_arg_errors( + &self, + compatibility_diagonal: IndexVec>, + formal_and_expected_inputs: IndexVec, Ty<'tcx>)>, + provided_args: IndexVec>, + c_variadic: bool, + err_code: &str, + fn_def_id: Option, + call_span: Span, + call_expr: &hir::Expr<'tcx>, + ) { + // Next, let's construct the error + let (error_span, full_call_span, ctor_of, is_method) = match &call_expr.kind { + hir::ExprKind::Call( + hir::Expr { hir_id, span, kind: hir::ExprKind::Path(qpath), .. }, + _, + ) => { + if let Res::Def(DefKind::Ctor(of, _), _) = + self.typeck_results.borrow().qpath_res(qpath, *hir_id) + { + (call_span, *span, Some(of), false) + } else { + (call_span, *span, None, false) + } + } + hir::ExprKind::Call(hir::Expr { span, .. }, _) => (call_span, *span, None, false), + hir::ExprKind::MethodCall(path_segment, _, _, span) => { + let ident_span = path_segment.ident.span; + let ident_span = if let Some(args) = path_segment.args { + ident_span.with_hi(args.span_ext.hi()) + } else { + ident_span + }; + // methods are never ctors + (*span, ident_span, None, true) + } + k => span_bug!(call_span, "checking argument types on a non-call: `{:?}`", k), + }; + let args_span = error_span.trim_start(full_call_span).unwrap_or(error_span); + let call_name = match ctor_of { + Some(CtorOf::Struct) => "struct", + Some(CtorOf::Variant) => "enum variant", + None => "function", + }; + + // Don't print if it has error types or is just plain `_` + fn has_error_or_infer<'tcx>(tys: impl IntoIterator>) -> bool { + tys.into_iter().any(|ty| ty.references_error() || ty.is_ty_var()) + } + + self.set_tainted_by_errors(); + let tcx = self.tcx; + + // Get the argument span in the context of the call span so that + // suggestions and labels are (more) correct when an arg is a + // macro invocation. + let normalize_span = |span: Span| -> Span { + let normalized_span = span.find_ancestor_inside(error_span).unwrap_or(span); + // Sometimes macros mess up the spans, so do not normalize the + // arg span to equal the error span, because that's less useful + // than pointing out the arg expr in the wrong context. + if normalized_span.source_equal(error_span) { span } else { normalized_span } + }; + + // Precompute the provided types and spans, since that's all we typically need for below + let provided_arg_tys: IndexVec, Span)> = provided_args + .iter() + .map(|expr| { + let ty = self + .typeck_results + .borrow() + .expr_ty_adjusted_opt(*expr) + .unwrap_or_else(|| tcx.ty_error()); + (self.resolve_vars_if_possible(ty), normalize_span(expr.span)) + }) + .collect(); + let callee_expr = match &call_expr.peel_blocks().kind { + hir::ExprKind::Call(callee, _) => Some(*callee), + hir::ExprKind::MethodCall(_, receiver, ..) => { + if let Some((DefKind::AssocFn, def_id)) = + self.typeck_results.borrow().type_dependent_def(call_expr.hir_id) + && let Some(assoc) = tcx.opt_associated_item(def_id) + && assoc.fn_has_self_parameter + { + Some(*receiver) + } else { + None + } + } + _ => None, + }; + let callee_ty = callee_expr + .and_then(|callee_expr| self.typeck_results.borrow().expr_ty_adjusted_opt(callee_expr)); + + // A "softer" version of the `demand_compatible`, which checks types without persisting them, + // and treats error types differently + // This will allow us to "probe" for other argument orders that would likely have been correct + let check_compatible = |provided_idx: ProvidedIdx, expected_idx: ExpectedIdx| { + if provided_idx.as_usize() == expected_idx.as_usize() { + return compatibility_diagonal[provided_idx].clone(); + } + + let (formal_input_ty, expected_input_ty) = formal_and_expected_inputs[expected_idx]; + // If either is an error type, we defy the usual convention and consider them to *not* be + // coercible. This prevents our error message heuristic from trying to pass errors into + // every argument. + if (formal_input_ty, expected_input_ty).references_error() { + return Compatibility::Incompatible(None); + } + + let (arg_ty, arg_span) = provided_arg_tys[provided_idx]; + + let expectation = Expectation::rvalue_hint(self, expected_input_ty); + let coerced_ty = expectation.only_has_type(self).unwrap_or(formal_input_ty); + let can_coerce = self.can_coerce(arg_ty, coerced_ty); + if !can_coerce { + return Compatibility::Incompatible(Some(ty::error::TypeError::Sorts( + ty::error::ExpectedFound::new(true, coerced_ty, arg_ty), + ))); + } + + // Using probe here, since we don't want this subtyping to affect inference. + let subtyping_error = self.probe(|_| { + self.at(&self.misc(arg_span), self.param_env).sup(formal_input_ty, coerced_ty).err() + }); + + // Same as above: if either the coerce type or the checked type is an error type, + // consider them *not* compatible. + let references_error = (coerced_ty, arg_ty).references_error(); + match (references_error, subtyping_error) { + (false, None) => Compatibility::Compatible, + (_, subtyping_error) => Compatibility::Incompatible(subtyping_error), + } + }; + + // The algorithm here is inspired by levenshtein distance and longest common subsequence. + // We'll try to detect 4 different types of mistakes: + // - An extra parameter has been provided that doesn't satisfy *any* of the other inputs + // - An input is missing, which isn't satisfied by *any* of the other arguments + // - Some number of arguments have been provided in the wrong order + // - A type is straight up invalid + + // First, let's find the errors + let (mut errors, matched_inputs) = + ArgMatrix::new(provided_args.len(), formal_and_expected_inputs.len(), check_compatible) + .find_errors(); + + // First, check if we just need to wrap some arguments in a tuple. + if let Some((mismatch_idx, terr)) = + compatibility_diagonal.iter().enumerate().find_map(|(i, c)| { + if let Compatibility::Incompatible(Some(terr)) = c { + Some((i, *terr)) + } else { + None + } + }) + { + // Is the first bad expected argument a tuple? + // Do we have as many extra provided arguments as the tuple's length? + // If so, we might have just forgotten to wrap some args in a tuple. + if let Some(ty::Tuple(tys)) = + formal_and_expected_inputs.get(mismatch_idx.into()).map(|tys| tys.1.kind()) + // If the tuple is unit, we're not actually wrapping any arguments. + && !tys.is_empty() + && provided_arg_tys.len() == formal_and_expected_inputs.len() - 1 + tys.len() + { + // Wrap up the N provided arguments starting at this position in a tuple. + let provided_as_tuple = tcx.mk_tup( + provided_arg_tys.iter().map(|(ty, _)| *ty).skip(mismatch_idx).take(tys.len()), + ); + + let mut satisfied = true; + // Check if the newly wrapped tuple + rest of the arguments are compatible. + for ((_, expected_ty), provided_ty) in std::iter::zip( + formal_and_expected_inputs.iter().skip(mismatch_idx), + [provided_as_tuple].into_iter().chain( + provided_arg_tys.iter().map(|(ty, _)| *ty).skip(mismatch_idx + tys.len()), + ), + ) { + if !self.can_coerce(provided_ty, *expected_ty) { + satisfied = false; + break; + } + } + + // If they're compatible, suggest wrapping in an arg, and we're done! + // Take some care with spans, so we don't suggest wrapping a macro's + // innards in parenthesis, for example. + if satisfied + && let Some((_, lo)) = + provided_arg_tys.get(ProvidedIdx::from_usize(mismatch_idx)) + && let Some((_, hi)) = + provided_arg_tys.get(ProvidedIdx::from_usize(mismatch_idx + tys.len() - 1)) + { + let mut err; + if tys.len() == 1 { + // A tuple wrap suggestion actually occurs within, + // so don't do anything special here. + err = self.err_ctxt().report_and_explain_type_error( + TypeTrace::types( + &self.misc(*lo), + true, + formal_and_expected_inputs[mismatch_idx.into()].1, + provided_arg_tys[mismatch_idx.into()].0, + ), + terr, + ); + err.span_label( + full_call_span, + format!("arguments to this {} are incorrect", call_name), + ); + } else { + err = tcx.sess.struct_span_err_with_code( + full_call_span, + &format!( + "this {} takes {}{} but {} {} supplied", + call_name, + if c_variadic { "at least " } else { "" }, + potentially_plural_count( + formal_and_expected_inputs.len(), + "argument" + ), + potentially_plural_count(provided_args.len(), "argument"), + pluralize!("was", provided_args.len()) + ), + DiagnosticId::Error(err_code.to_owned()), + ); + err.multipart_suggestion_verbose( + "wrap these arguments in parentheses to construct a tuple", + vec![ + (lo.shrink_to_lo(), "(".to_string()), + (hi.shrink_to_hi(), ")".to_string()), + ], + Applicability::MachineApplicable, + ); + }; + self.label_fn_like( + &mut err, + fn_def_id, + callee_ty, + Some(mismatch_idx), + is_method, + ); + err.emit(); + return; + } + } + } + + // Okay, so here's where it gets complicated in regards to what errors + // we emit and how. + // There are 3 different "types" of errors we might encounter. + // 1) Missing/extra/swapped arguments + // 2) Valid but incorrect arguments + // 3) Invalid arguments + // - Currently I think this only comes up with `CyclicTy` + // + // We first need to go through, remove those from (3) and emit those + // as their own error, particularly since they're error code and + // message is special. From what I can tell, we *must* emit these + // here (vs somewhere prior to this function) since the arguments + // become invalid *because* of how they get used in the function. + // It is what it is. + + if errors.is_empty() { + if cfg!(debug_assertions) { + span_bug!(error_span, "expected errors from argument matrix"); + } else { + tcx.sess + .struct_span_err( + error_span, + "argument type mismatch was detected, \ + but rustc had trouble determining where", + ) + .note( + "we would appreciate a bug report: \ + https://github.com/rust-lang/rust/issues/new", + ) + .emit(); + } + return; + } + + errors.drain_filter(|error| { + let Error::Invalid(provided_idx, expected_idx, Compatibility::Incompatible(Some(e))) = error else { return false }; + let (provided_ty, provided_span) = provided_arg_tys[*provided_idx]; + let (expected_ty, _) = formal_and_expected_inputs[*expected_idx]; + let cause = &self.misc(provided_span); + let trace = TypeTrace::types(cause, true, expected_ty, provided_ty); + if !matches!(trace.cause.as_failure_code(*e), FailureCode::Error0308(_)) { + self.err_ctxt().report_and_explain_type_error(trace, *e).emit(); + return true; + } + false + }); + + // We're done if we found errors, but we already emitted them. + if errors.is_empty() { + return; + } + + // Okay, now that we've emitted the special errors separately, we + // are only left missing/extra/swapped and mismatched arguments, both + // can be collated pretty easily if needed. + + // Next special case: if there is only one "Incompatible" error, just emit that + if let [ + Error::Invalid(provided_idx, expected_idx, Compatibility::Incompatible(Some(err))), + ] = &errors[..] + { + let (formal_ty, expected_ty) = formal_and_expected_inputs[*expected_idx]; + let (provided_ty, provided_arg_span) = provided_arg_tys[*provided_idx]; + let cause = &self.misc(provided_arg_span); + let trace = TypeTrace::types(cause, true, expected_ty, provided_ty); + let mut err = self.err_ctxt().report_and_explain_type_error(trace, *err); + self.emit_coerce_suggestions( + &mut err, + &provided_args[*provided_idx], + provided_ty, + Expectation::rvalue_hint(self, expected_ty) + .only_has_type(self) + .unwrap_or(formal_ty), + None, + None, + ); + err.span_label( + full_call_span, + format!("arguments to this {} are incorrect", call_name), + ); + // Call out where the function is defined + self.label_fn_like( + &mut err, + fn_def_id, + callee_ty, + Some(expected_idx.as_usize()), + is_method, + ); + err.emit(); + return; + } + + let mut err = if formal_and_expected_inputs.len() == provided_args.len() { + struct_span_err!( + tcx.sess, + full_call_span, + E0308, + "arguments to this {} are incorrect", + call_name, + ) + } else { + tcx.sess.struct_span_err_with_code( + full_call_span, + &format!( + "this {} takes {}{} but {} {} supplied", + call_name, + if c_variadic { "at least " } else { "" }, + potentially_plural_count(formal_and_expected_inputs.len(), "argument"), + potentially_plural_count(provided_args.len(), "argument"), + pluralize!("was", provided_args.len()) + ), + DiagnosticId::Error(err_code.to_owned()), + ) + }; + + // As we encounter issues, keep track of what we want to provide for the suggestion + let mut labels = vec![]; + // If there is a single error, we give a specific suggestion; otherwise, we change to + // "did you mean" with the suggested function call + enum SuggestionText { + None, + Provide(bool), + Remove(bool), + Swap, + Reorder, + DidYouMean, + } + let mut suggestion_text = SuggestionText::None; + + let mut errors = errors.into_iter().peekable(); + while let Some(error) = errors.next() { + match error { + Error::Invalid(provided_idx, expected_idx, compatibility) => { + let (formal_ty, expected_ty) = formal_and_expected_inputs[expected_idx]; + let (provided_ty, provided_span) = provided_arg_tys[provided_idx]; + if let Compatibility::Incompatible(error) = compatibility { + let cause = &self.misc(provided_span); + let trace = TypeTrace::types(cause, true, expected_ty, provided_ty); + if let Some(e) = error { + self.err_ctxt().note_type_err( + &mut err, + &trace.cause, + None, + Some(trace.values), + e, + false, + true, + ); + } + } + + self.emit_coerce_suggestions( + &mut err, + &provided_args[provided_idx], + provided_ty, + Expectation::rvalue_hint(self, expected_ty) + .only_has_type(self) + .unwrap_or(formal_ty), + None, + None, + ); + } + Error::Extra(arg_idx) => { + let (provided_ty, provided_span) = provided_arg_tys[arg_idx]; + let provided_ty_name = if !has_error_or_infer([provided_ty]) { + // FIXME: not suggestable, use something else + format!(" of type `{}`", provided_ty) + } else { + "".to_string() + }; + labels + .push((provided_span, format!("argument{} unexpected", provided_ty_name))); + suggestion_text = match suggestion_text { + SuggestionText::None => SuggestionText::Remove(false), + SuggestionText::Remove(_) => SuggestionText::Remove(true), + _ => SuggestionText::DidYouMean, + }; + } + Error::Missing(expected_idx) => { + // If there are multiple missing arguments adjacent to each other, + // then we can provide a single error. + + let mut missing_idxs = vec![expected_idx]; + while let Some(e) = errors.next_if(|e| { + matches!(e, Error::Missing(next_expected_idx) + if *next_expected_idx == *missing_idxs.last().unwrap() + 1) + }) { + match e { + Error::Missing(expected_idx) => missing_idxs.push(expected_idx), + _ => unreachable!(), + } + } + + // NOTE: Because we might be re-arranging arguments, might have extra + // arguments, etc. it's hard to *really* know where we should provide + // this error label, so as a heuristic, we point to the provided arg, or + // to the call if the missing inputs pass the provided args. + match &missing_idxs[..] { + &[expected_idx] => { + let (_, input_ty) = formal_and_expected_inputs[expected_idx]; + let span = if let Some((_, arg_span)) = + provided_arg_tys.get(expected_idx.to_provided_idx()) + { + *arg_span + } else { + args_span + }; + let rendered = if !has_error_or_infer([input_ty]) { + format!(" of type `{}`", input_ty) + } else { + "".to_string() + }; + labels.push((span, format!("an argument{} is missing", rendered))); + suggestion_text = match suggestion_text { + SuggestionText::None => SuggestionText::Provide(false), + SuggestionText::Provide(_) => SuggestionText::Provide(true), + _ => SuggestionText::DidYouMean, + }; + } + &[first_idx, second_idx] => { + let (_, first_expected_ty) = formal_and_expected_inputs[first_idx]; + let (_, second_expected_ty) = formal_and_expected_inputs[second_idx]; + let span = if let (Some((_, first_span)), Some((_, second_span))) = ( + provided_arg_tys.get(first_idx.to_provided_idx()), + provided_arg_tys.get(second_idx.to_provided_idx()), + ) { + first_span.to(*second_span) + } else { + args_span + }; + let rendered = + if !has_error_or_infer([first_expected_ty, second_expected_ty]) { + format!( + " of type `{}` and `{}`", + first_expected_ty, second_expected_ty + ) + } else { + "".to_string() + }; + labels.push((span, format!("two arguments{} are missing", rendered))); + suggestion_text = match suggestion_text { + SuggestionText::None | SuggestionText::Provide(_) => { + SuggestionText::Provide(true) + } + _ => SuggestionText::DidYouMean, + }; + } + &[first_idx, second_idx, third_idx] => { + let (_, first_expected_ty) = formal_and_expected_inputs[first_idx]; + let (_, second_expected_ty) = formal_and_expected_inputs[second_idx]; + let (_, third_expected_ty) = formal_and_expected_inputs[third_idx]; + let span = if let (Some((_, first_span)), Some((_, third_span))) = ( + provided_arg_tys.get(first_idx.to_provided_idx()), + provided_arg_tys.get(third_idx.to_provided_idx()), + ) { + first_span.to(*third_span) + } else { + args_span + }; + let rendered = if !has_error_or_infer([ + first_expected_ty, + second_expected_ty, + third_expected_ty, + ]) { + format!( + " of type `{}`, `{}`, and `{}`", + first_expected_ty, second_expected_ty, third_expected_ty + ) + } else { + "".to_string() + }; + labels.push((span, format!("three arguments{} are missing", rendered))); + suggestion_text = match suggestion_text { + SuggestionText::None | SuggestionText::Provide(_) => { + SuggestionText::Provide(true) + } + _ => SuggestionText::DidYouMean, + }; + } + missing_idxs => { + let first_idx = *missing_idxs.first().unwrap(); + let last_idx = *missing_idxs.last().unwrap(); + // NOTE: Because we might be re-arranging arguments, might have extra arguments, etc. + // It's hard to *really* know where we should provide this error label, so this is a + // decent heuristic + let span = if let (Some((_, first_span)), Some((_, last_span))) = ( + provided_arg_tys.get(first_idx.to_provided_idx()), + provided_arg_tys.get(last_idx.to_provided_idx()), + ) { + first_span.to(*last_span) + } else { + args_span + }; + labels.push((span, format!("multiple arguments are missing"))); + suggestion_text = match suggestion_text { + SuggestionText::None | SuggestionText::Provide(_) => { + SuggestionText::Provide(true) + } + _ => SuggestionText::DidYouMean, + }; + } + } + } + Error::Swap( + first_provided_idx, + second_provided_idx, + first_expected_idx, + second_expected_idx, + ) => { + let (first_provided_ty, first_span) = provided_arg_tys[first_provided_idx]; + let (_, first_expected_ty) = formal_and_expected_inputs[first_expected_idx]; + let first_provided_ty_name = if !has_error_or_infer([first_provided_ty]) { + format!(", found `{}`", first_provided_ty) + } else { + String::new() + }; + labels.push(( + first_span, + format!("expected `{}`{}", first_expected_ty, first_provided_ty_name), + )); + + let (second_provided_ty, second_span) = provided_arg_tys[second_provided_idx]; + let (_, second_expected_ty) = formal_and_expected_inputs[second_expected_idx]; + let second_provided_ty_name = if !has_error_or_infer([second_provided_ty]) { + format!(", found `{}`", second_provided_ty) + } else { + String::new() + }; + labels.push(( + second_span, + format!("expected `{}`{}", second_expected_ty, second_provided_ty_name), + )); + + suggestion_text = match suggestion_text { + SuggestionText::None => SuggestionText::Swap, + _ => SuggestionText::DidYouMean, + }; + } + Error::Permutation(args) => { + for (dst_arg, dest_input) in args { + let (_, expected_ty) = formal_and_expected_inputs[dst_arg]; + let (provided_ty, provided_span) = provided_arg_tys[dest_input]; + let provided_ty_name = if !has_error_or_infer([provided_ty]) { + format!(", found `{}`", provided_ty) + } else { + String::new() + }; + labels.push(( + provided_span, + format!("expected `{}`{}", expected_ty, provided_ty_name), + )); + } + + suggestion_text = match suggestion_text { + SuggestionText::None => SuggestionText::Reorder, + _ => SuggestionText::DidYouMean, + }; + } + } + } + + // If we have less than 5 things to say, it would be useful to call out exactly what's wrong + if labels.len() <= 5 { + for (span, label) in labels { + err.span_label(span, label); + } + } + + // Call out where the function is defined + self.label_fn_like(&mut err, fn_def_id, callee_ty, None, is_method); + + // And add a suggestion block for all of the parameters + let suggestion_text = match suggestion_text { + SuggestionText::None => None, + SuggestionText::Provide(plural) => { + Some(format!("provide the argument{}", if plural { "s" } else { "" })) + } + SuggestionText::Remove(plural) => { + Some(format!("remove the extra argument{}", if plural { "s" } else { "" })) + } + SuggestionText::Swap => Some("swap these arguments".to_string()), + SuggestionText::Reorder => Some("reorder these arguments".to_string()), + SuggestionText::DidYouMean => Some("did you mean".to_string()), + }; + if let Some(suggestion_text) = suggestion_text { + let source_map = self.sess().source_map(); + let (mut suggestion, suggestion_span) = + if let Some(call_span) = full_call_span.find_ancestor_inside(error_span) { + ("(".to_string(), call_span.shrink_to_hi().to(error_span.shrink_to_hi())) + } else { + ( + format!( + "{}(", + source_map.span_to_snippet(full_call_span).unwrap_or_else(|_| { + fn_def_id.map_or("".to_string(), |fn_def_id| { + tcx.item_name(fn_def_id).to_string() + }) + }) + ), + error_span, + ) + }; + let mut needs_comma = false; + for (expected_idx, provided_idx) in matched_inputs.iter_enumerated() { + if needs_comma { + suggestion += ", "; + } else { + needs_comma = true; + } + let suggestion_text = if let Some(provided_idx) = provided_idx + && let (_, provided_span) = provided_arg_tys[*provided_idx] + && let Ok(arg_text) = source_map.span_to_snippet(provided_span) + { + arg_text + } else { + // Propose a placeholder of the correct type + let (_, expected_ty) = formal_and_expected_inputs[expected_idx]; + if expected_ty.is_unit() { + "()".to_string() + } else if expected_ty.is_suggestable(tcx, false) { + format!("/* {} */", expected_ty) + } else { + "/* value */".to_string() + } + }; + suggestion += &suggestion_text; + } + suggestion += ")"; + err.span_suggestion_verbose( + suggestion_span, + &suggestion_text, + suggestion, + Applicability::HasPlaceholders, + ); + } + + err.emit(); + } + + // AST fragment checking + pub(in super::super) fn check_lit( + &self, + lit: &hir::Lit, + expected: Expectation<'tcx>, + ) -> Ty<'tcx> { + let tcx = self.tcx; + + match lit.node { + ast::LitKind::Str(..) => tcx.mk_static_str(), + ast::LitKind::ByteStr(ref v) => { + tcx.mk_imm_ref(tcx.lifetimes.re_static, tcx.mk_array(tcx.types.u8, v.len() as u64)) + } + ast::LitKind::Byte(_) => tcx.types.u8, + ast::LitKind::Char(_) => tcx.types.char, + ast::LitKind::Int(_, ast::LitIntType::Signed(t)) => tcx.mk_mach_int(ty::int_ty(t)), + ast::LitKind::Int(_, ast::LitIntType::Unsigned(t)) => tcx.mk_mach_uint(ty::uint_ty(t)), + ast::LitKind::Int(_, ast::LitIntType::Unsuffixed) => { + let opt_ty = expected.to_option(self).and_then(|ty| match ty.kind() { + ty::Int(_) | ty::Uint(_) => Some(ty), + ty::Char => Some(tcx.types.u8), + ty::RawPtr(..) => Some(tcx.types.usize), + ty::FnDef(..) | ty::FnPtr(_) => Some(tcx.types.usize), + _ => None, + }); + opt_ty.unwrap_or_else(|| self.next_int_var()) + } + ast::LitKind::Float(_, ast::LitFloatType::Suffixed(t)) => { + tcx.mk_mach_float(ty::float_ty(t)) + } + ast::LitKind::Float(_, ast::LitFloatType::Unsuffixed) => { + let opt_ty = expected.to_option(self).and_then(|ty| match ty.kind() { + ty::Float(_) => Some(ty), + _ => None, + }); + opt_ty.unwrap_or_else(|| self.next_float_var()) + } + ast::LitKind::Bool(_) => tcx.types.bool, + ast::LitKind::Err => tcx.ty_error(), + } + } + + pub fn check_struct_path( + &self, + qpath: &QPath<'_>, + hir_id: hir::HirId, + ) -> Option<(&'tcx ty::VariantDef, Ty<'tcx>)> { + let path_span = qpath.span(); + let (def, ty) = self.finish_resolving_struct_path(qpath, path_span, hir_id); + let variant = match def { + Res::Err => { + self.set_tainted_by_errors(); + return None; + } + Res::Def(DefKind::Variant, _) => match ty.kind() { + ty::Adt(adt, substs) => Some((adt.variant_of_res(def), adt.did(), substs)), + _ => bug!("unexpected type: {:?}", ty), + }, + Res::Def(DefKind::Struct | DefKind::Union | DefKind::TyAlias | DefKind::AssocTy, _) + | Res::SelfTyParam { .. } + | Res::SelfTyAlias { .. } => match ty.kind() { + ty::Adt(adt, substs) if !adt.is_enum() => { + Some((adt.non_enum_variant(), adt.did(), substs)) + } + _ => None, + }, + _ => bug!("unexpected definition: {:?}", def), + }; + + if let Some((variant, did, substs)) = variant { + debug!("check_struct_path: did={:?} substs={:?}", did, substs); + self.write_user_type_annotation_from_substs(hir_id, did, substs, None); + + // Check bounds on type arguments used in the path. + self.add_required_obligations_for_hir(path_span, did, substs, hir_id); + + Some((variant, ty)) + } else { + match ty.kind() { + ty::Error(_) => { + // E0071 might be caused by a spelling error, which will have + // already caused an error message and probably a suggestion + // elsewhere. Refrain from emitting more unhelpful errors here + // (issue #88844). + } + _ => { + struct_span_err!( + self.tcx.sess, + path_span, + E0071, + "expected struct, variant or union type, found {}", + ty.sort_string(self.tcx) + ) + .span_label(path_span, "not a struct") + .emit(); + } + } + None + } + } + + pub fn check_decl_initializer( + &self, + hir_id: hir::HirId, + pat: &'tcx hir::Pat<'tcx>, + init: &'tcx hir::Expr<'tcx>, + ) -> Ty<'tcx> { + // FIXME(tschottdorf): `contains_explicit_ref_binding()` must be removed + // for #42640 (default match binding modes). + // + // See #44848. + let ref_bindings = pat.contains_explicit_ref_binding(); + + let local_ty = self.local_ty(init.span, hir_id).revealed_ty; + if let Some(m) = ref_bindings { + // Somewhat subtle: if we have a `ref` binding in the pattern, + // we want to avoid introducing coercions for the RHS. This is + // both because it helps preserve sanity and, in the case of + // ref mut, for soundness (issue #23116). In particular, in + // the latter case, we need to be clear that the type of the + // referent for the reference that results is *equal to* the + // type of the place it is referencing, and not some + // supertype thereof. + let init_ty = self.check_expr_with_needs(init, Needs::maybe_mut_place(m)); + self.demand_eqtype(init.span, local_ty, init_ty); + init_ty + } else { + self.check_expr_coercable_to_type(init, local_ty, None) + } + } + + pub(in super::super) fn check_decl(&self, decl: Declaration<'tcx>) { + // Determine and write the type which we'll check the pattern against. + let decl_ty = self.local_ty(decl.span, decl.hir_id).decl_ty; + self.write_ty(decl.hir_id, decl_ty); + + // Type check the initializer. + if let Some(ref init) = decl.init { + let init_ty = self.check_decl_initializer(decl.hir_id, decl.pat, &init); + self.overwrite_local_ty_if_err(decl.hir_id, decl.pat, decl_ty, init_ty); + } + + // Does the expected pattern type originate from an expression and what is the span? + let (origin_expr, ty_span) = match (decl.ty, decl.init) { + (Some(ty), _) => (false, Some(ty.span)), // Bias towards the explicit user type. + (_, Some(init)) => { + (true, Some(init.span.find_ancestor_inside(decl.span).unwrap_or(init.span))) + } // No explicit type; so use the scrutinee. + _ => (false, None), // We have `let $pat;`, so the expected type is unconstrained. + }; + + // Type check the pattern. Override if necessary to avoid knock-on errors. + self.check_pat_top(&decl.pat, decl_ty, ty_span, origin_expr); + let pat_ty = self.node_ty(decl.pat.hir_id); + self.overwrite_local_ty_if_err(decl.hir_id, decl.pat, decl_ty, pat_ty); + + if let Some(blk) = decl.els { + let previous_diverges = self.diverges.get(); + let else_ty = self.check_block_with_expected(blk, NoExpectation); + let cause = self.cause(blk.span, ObligationCauseCode::LetElse); + if let Some(mut err) = + self.demand_eqtype_with_origin(&cause, self.tcx.types.never, else_ty) + { + err.emit(); + } + self.diverges.set(previous_diverges); + } + } + + /// Type check a `let` statement. + pub fn check_decl_local(&self, local: &'tcx hir::Local<'tcx>) { + self.check_decl(local.into()); + } + + pub fn check_stmt(&self, stmt: &'tcx hir::Stmt<'tcx>, is_last: bool) { + // Don't do all the complex logic below for `DeclItem`. + match stmt.kind { + hir::StmtKind::Item(..) => return, + hir::StmtKind::Local(..) | hir::StmtKind::Expr(..) | hir::StmtKind::Semi(..) => {} + } + + self.warn_if_unreachable(stmt.hir_id, stmt.span, "statement"); + + // Hide the outer diverging and `has_errors` flags. + let old_diverges = self.diverges.replace(Diverges::Maybe); + let old_has_errors = self.has_errors.replace(false); + + match stmt.kind { + hir::StmtKind::Local(l) => { + self.check_decl_local(l); + } + // Ignore for now. + hir::StmtKind::Item(_) => {} + hir::StmtKind::Expr(ref expr) => { + // Check with expected type of `()`. + self.check_expr_has_type_or_error(&expr, self.tcx.mk_unit(), |err| { + if expr.can_have_side_effects() { + self.suggest_semicolon_at_end(expr.span, err); + } + }); + } + hir::StmtKind::Semi(ref expr) => { + // All of this is equivalent to calling `check_expr`, but it is inlined out here + // in order to capture the fact that this `match` is the last statement in its + // function. This is done for better suggestions to remove the `;`. + let expectation = match expr.kind { + hir::ExprKind::Match(..) if is_last => IsLast(stmt.span), + _ => NoExpectation, + }; + self.check_expr_with_expectation(expr, expectation); + } + } + + // Combine the diverging and `has_error` flags. + self.diverges.set(self.diverges.get() | old_diverges); + self.has_errors.set(self.has_errors.get() | old_has_errors); + } + + pub fn check_block_no_value(&self, blk: &'tcx hir::Block<'tcx>) { + let unit = self.tcx.mk_unit(); + let ty = self.check_block_with_expected(blk, ExpectHasType(unit)); + + // if the block produces a `!` value, that can always be + // (effectively) coerced to unit. + if !ty.is_never() { + self.demand_suptype(blk.span, unit, ty); + } + } + + pub(in super::super) fn check_block_with_expected( + &self, + blk: &'tcx hir::Block<'tcx>, + expected: Expectation<'tcx>, + ) -> Ty<'tcx> { + let prev = self.ps.replace(self.ps.get().recurse(blk)); + + // In some cases, blocks have just one exit, but other blocks + // can be targeted by multiple breaks. This can happen both + // with labeled blocks as well as when we desugar + // a `try { ... }` expression. + // + // Example 1: + // + // 'a: { if true { break 'a Err(()); } Ok(()) } + // + // Here we would wind up with two coercions, one from + // `Err(())` and the other from the tail expression + // `Ok(())`. If the tail expression is omitted, that's a + // "forced unit" -- unless the block diverges, in which + // case we can ignore the tail expression (e.g., `'a: { + // break 'a 22; }` would not force the type of the block + // to be `()`). + let tail_expr = blk.expr.as_ref(); + let coerce_to_ty = expected.coercion_target_type(self, blk.span); + let coerce = if blk.targeted_by_break { + CoerceMany::new(coerce_to_ty) + } else { + let tail_expr: &[&hir::Expr<'_>] = match tail_expr { + Some(e) => slice::from_ref(e), + None => &[], + }; + CoerceMany::with_coercion_sites(coerce_to_ty, tail_expr) + }; + + let prev_diverges = self.diverges.get(); + let ctxt = BreakableCtxt { coerce: Some(coerce), may_break: false }; + + let (ctxt, ()) = self.with_breakable_ctxt(blk.hir_id, ctxt, || { + for (pos, s) in blk.stmts.iter().enumerate() { + self.check_stmt(s, blk.stmts.len() - 1 == pos); + } + + // check the tail expression **without** holding the + // `enclosing_breakables` lock below. + let tail_expr_ty = tail_expr.map(|t| self.check_expr_with_expectation(t, expected)); + + let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); + let ctxt = enclosing_breakables.find_breakable(blk.hir_id); + let coerce = ctxt.coerce.as_mut().unwrap(); + if let Some(tail_expr_ty) = tail_expr_ty { + let tail_expr = tail_expr.unwrap(); + let span = self.get_expr_coercion_span(tail_expr); + let cause = self.cause(span, ObligationCauseCode::BlockTailExpression(blk.hir_id)); + let ty_for_diagnostic = coerce.merged_ty(); + // We use coerce_inner here because we want to augment the error + // suggesting to wrap the block in square brackets if it might've + // been mistaken array syntax + coerce.coerce_inner( + self, + &cause, + Some(tail_expr), + tail_expr_ty, + Some(&mut |diag: &mut Diagnostic| { + self.suggest_block_to_brackets(diag, blk, tail_expr_ty, ty_for_diagnostic); + }), + false, + ); + } else { + // Subtle: if there is no explicit tail expression, + // that is typically equivalent to a tail expression + // of `()` -- except if the block diverges. In that + // case, there is no value supplied from the tail + // expression (assuming there are no other breaks, + // this implies that the type of the block will be + // `!`). + // + // #41425 -- label the implicit `()` as being the + // "found type" here, rather than the "expected type". + if !self.diverges.get().is_always() { + // #50009 -- Do not point at the entire fn block span, point at the return type + // span, as it is the cause of the requirement, and + // `consider_hint_about_removing_semicolon` will point at the last expression + // if it were a relevant part of the error. This improves usability in editors + // that highlight errors inline. + let mut sp = blk.span; + let mut fn_span = None; + if let Some((decl, ident)) = self.get_parent_fn_decl(blk.hir_id) { + let ret_sp = decl.output.span(); + if let Some(block_sp) = self.parent_item_span(blk.hir_id) { + // HACK: on some cases (`ui/liveness/liveness-issue-2163.rs`) the + // output would otherwise be incorrect and even misleading. Make sure + // the span we're aiming at correspond to a `fn` body. + if block_sp == blk.span { + sp = ret_sp; + fn_span = Some(ident.span); + } + } + } + coerce.coerce_forced_unit( + self, + &self.misc(sp), + &mut |err| { + if let Some(expected_ty) = expected.only_has_type(self) { + if !self.consider_removing_semicolon(blk, expected_ty, err) { + self.err_ctxt().consider_returning_binding( + blk, + expected_ty, + err, + ); + } + if expected_ty == self.tcx.types.bool { + // If this is caused by a missing `let` in a `while let`, + // silence this redundant error, as we already emit E0070. + + // Our block must be a `assign desugar local; assignment` + if let Some(hir::Node::Block(hir::Block { + stmts: + [ + hir::Stmt { + kind: + hir::StmtKind::Local(hir::Local { + source: + hir::LocalSource::AssignDesugar(_), + .. + }), + .. + }, + hir::Stmt { + kind: + hir::StmtKind::Expr(hir::Expr { + kind: hir::ExprKind::Assign(..), + .. + }), + .. + }, + ], + .. + })) = self.tcx.hir().find(blk.hir_id) + { + self.comes_from_while_condition(blk.hir_id, |_| { + err.downgrade_to_delayed_bug(); + }) + } + } + } + if let Some(fn_span) = fn_span { + err.span_label( + fn_span, + "implicitly returns `()` as its body has no tail or `return` \ + expression", + ); + } + }, + false, + ); + } + } + }); + + if ctxt.may_break { + // If we can break from the block, then the block's exit is always reachable + // (... as long as the entry is reachable) - regardless of the tail of the block. + self.diverges.set(prev_diverges); + } + + let mut ty = ctxt.coerce.unwrap().complete(self); + + if self.has_errors.get() || ty.references_error() { + ty = self.tcx.ty_error() + } + + self.write_ty(blk.hir_id, ty); + + self.ps.set(prev); + ty + } + + fn parent_item_span(&self, id: hir::HirId) -> Option { + let node = self.tcx.hir().get_by_def_id(self.tcx.hir().get_parent_item(id).def_id); + match node { + Node::Item(&hir::Item { kind: hir::ItemKind::Fn(_, _, body_id), .. }) + | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Fn(_, body_id), .. }) => { + let body = self.tcx.hir().body(body_id); + if let ExprKind::Block(block, _) = &body.value.kind { + return Some(block.span); + } + } + _ => {} + } + None + } + + /// Given a function block's `HirId`, returns its `FnDecl` if it exists, or `None` otherwise. + fn get_parent_fn_decl(&self, blk_id: hir::HirId) -> Option<(&'tcx hir::FnDecl<'tcx>, Ident)> { + let parent = self.tcx.hir().get_by_def_id(self.tcx.hir().get_parent_item(blk_id).def_id); + self.get_node_fn_decl(parent).map(|(fn_decl, ident, _)| (fn_decl, ident)) + } + + /// If `expr` is a `match` expression that has only one non-`!` arm, use that arm's tail + /// expression's `Span`, otherwise return `expr.span`. This is done to give better errors + /// when given code like the following: + /// ```text + /// if false { return 0i32; } else { 1u32 } + /// // ^^^^ point at this instead of the whole `if` expression + /// ``` + fn get_expr_coercion_span(&self, expr: &hir::Expr<'_>) -> rustc_span::Span { + let check_in_progress = |elem: &hir::Expr<'_>| { + self.typeck_results.borrow().node_type_opt(elem.hir_id).filter(|ty| !ty.is_never()).map( + |_| match elem.kind { + // Point at the tail expression when possible. + hir::ExprKind::Block(block, _) => block.expr.map_or(block.span, |e| e.span), + _ => elem.span, + }, + ) + }; + + if let hir::ExprKind::If(_, _, Some(el)) = expr.kind { + if let Some(rslt) = check_in_progress(el) { + return rslt; + } + } + + if let hir::ExprKind::Match(_, arms, _) = expr.kind { + let mut iter = arms.iter().filter_map(|arm| check_in_progress(arm.body)); + if let Some(span) = iter.next() { + if iter.next().is_none() { + return span; + } + } + } + + expr.span + } + + fn overwrite_local_ty_if_err( + &self, + hir_id: hir::HirId, + pat: &'tcx hir::Pat<'tcx>, + decl_ty: Ty<'tcx>, + ty: Ty<'tcx>, + ) { + if ty.references_error() { + // Override the types everywhere with `err()` to avoid knock on errors. + self.write_ty(hir_id, ty); + self.write_ty(pat.hir_id, ty); + let local_ty = LocalTy { decl_ty, revealed_ty: ty }; + self.locals.borrow_mut().insert(hir_id, local_ty); + self.locals.borrow_mut().insert(pat.hir_id, local_ty); + } + } + + // Finish resolving a path in a struct expression or pattern `S::A { .. }` if necessary. + // The newly resolved definition is written into `type_dependent_defs`. + fn finish_resolving_struct_path( + &self, + qpath: &QPath<'_>, + path_span: Span, + hir_id: hir::HirId, + ) -> (Res, Ty<'tcx>) { + match *qpath { + QPath::Resolved(ref maybe_qself, ref path) => { + let self_ty = maybe_qself.as_ref().map(|qself| self.to_ty(qself)); + let ty = >::res_to_ty(self, self_ty, path, true); + (path.res, ty) + } + QPath::TypeRelative(ref qself, ref segment) => { + let ty = self.to_ty(qself); + + let result = >::associated_path_to_ty( + self, hir_id, path_span, ty, qself, segment, true, + ); + let ty = result.map(|(ty, _, _)| ty).unwrap_or_else(|_| self.tcx().ty_error()); + let result = result.map(|(_, kind, def_id)| (kind, def_id)); + + // Write back the new resolution. + self.write_resolution(hir_id, result); + + (result.map_or(Res::Err, |(kind, def_id)| Res::Def(kind, def_id)), ty) + } + QPath::LangItem(lang_item, span, id) => { + self.resolve_lang_item_path(lang_item, span, hir_id, id) + } + } + } + + /// Given a vector of fulfillment errors, try to adjust the spans of the + /// errors to more accurately point at the cause of the failure. + /// + /// This applies to calls, methods, and struct expressions. This will also + /// try to deduplicate errors that are due to the same cause but might + /// have been created with different [`ObligationCause`][traits::ObligationCause]s. + pub(super) fn adjust_fulfillment_errors_for_expr_obligation( + &self, + errors: &mut Vec>, + ) { + // Store a mapping from `(Span, Predicate) -> ObligationCause`, so that + // other errors that have the same span and predicate can also get fixed, + // even if their `ObligationCauseCode` isn't an `Expr*Obligation` kind. + // This is important since if we adjust one span but not the other, then + // we will have "duplicated" the error on the UI side. + let mut remap_cause = FxHashSet::default(); + let mut not_adjusted = vec![]; + + for error in errors { + let before_span = error.obligation.cause.span; + if self.adjust_fulfillment_error_for_expr_obligation(error) + || before_span != error.obligation.cause.span + { + // Store both the predicate and the predicate *without constness* + // since sometimes we instantiate and check both of these in a + // method call, for example. + remap_cause.insert(( + before_span, + error.obligation.predicate, + error.obligation.cause.clone(), + )); + remap_cause.insert(( + before_span, + error.obligation.predicate.without_const(self.tcx), + error.obligation.cause.clone(), + )); + } else { + // If it failed to be adjusted once around, it may be adjusted + // via the "remap cause" mapping the second time... + not_adjusted.push(error); + } + } + + for error in not_adjusted { + for (span, predicate, cause) in &remap_cause { + if *predicate == error.obligation.predicate + && span.contains(error.obligation.cause.span) + { + error.obligation.cause = cause.clone(); + continue; + } + } + } + } + + fn adjust_fulfillment_error_for_expr_obligation( + &self, + error: &mut traits::FulfillmentError<'tcx>, + ) -> bool { + let (traits::ExprItemObligation(def_id, hir_id, idx) | traits::ExprBindingObligation(def_id, _, hir_id, idx)) + = *error.obligation.cause.code().peel_derives() else { return false; }; + let hir = self.tcx.hir(); + let hir::Node::Expr(expr) = hir.get(hir_id) else { return false; }; + + // Skip over mentioning async lang item + if Some(def_id) == self.tcx.lang_items().from_generator_fn() + && error.obligation.cause.span.desugaring_kind() + == Some(rustc_span::DesugaringKind::Async) + { + return false; + } + + let Some(unsubstituted_pred) = + self.tcx.predicates_of(def_id).instantiate_identity(self.tcx).predicates.into_iter().nth(idx) + else { return false; }; + + let generics = self.tcx.generics_of(def_id); + let predicate_substs = match unsubstituted_pred.kind().skip_binder() { + ty::PredicateKind::Trait(pred) => pred.trait_ref.substs, + ty::PredicateKind::Projection(pred) => pred.projection_ty.substs, + _ => ty::List::empty(), + }; + + let find_param_matching = |matches: &dyn Fn(&ty::ParamTy) -> bool| { + predicate_substs.types().find_map(|ty| { + ty.walk().find_map(|arg| { + if let ty::GenericArgKind::Type(ty) = arg.unpack() + && let ty::Param(param_ty) = ty.kind() + && matches(param_ty) + { + Some(arg) + } else { + None + } + }) + }) + }; + + // Prefer generics that are local to the fn item, since these are likely + // to be the cause of the unsatisfied predicate. + let mut param_to_point_at = find_param_matching(&|param_ty| { + self.tcx.parent(generics.type_param(param_ty, self.tcx).def_id) == def_id + }); + // Fall back to generic that isn't local to the fn item. This will come + // from a trait or impl, for example. + let mut fallback_param_to_point_at = find_param_matching(&|param_ty| { + self.tcx.parent(generics.type_param(param_ty, self.tcx).def_id) != def_id + && param_ty.name != rustc_span::symbol::kw::SelfUpper + }); + // Finally, the `Self` parameter is possibly the reason that the predicate + // is unsatisfied. This is less likely to be true for methods, because + // method probe means that we already kinda check that the predicates due + // to the `Self` type are true. + let mut self_param_to_point_at = + find_param_matching(&|param_ty| param_ty.name == rustc_span::symbol::kw::SelfUpper); + + // Finally, for ambiguity-related errors, we actually want to look + // for a parameter that is the source of the inference type left + // over in this predicate. + if let traits::FulfillmentErrorCode::CodeAmbiguity = error.code { + fallback_param_to_point_at = None; + self_param_to_point_at = None; + param_to_point_at = + self.find_ambiguous_parameter_in(def_id, error.root_obligation.predicate); + } + + if self.closure_span_overlaps_error(error, expr.span) { + return false; + } + + match &expr.kind { + hir::ExprKind::Path(qpath) => { + if let hir::Node::Expr(hir::Expr { + kind: hir::ExprKind::Call(callee, args), + hir_id: call_hir_id, + span: call_span, + .. + }) = hir.get(hir.get_parent_node(expr.hir_id)) + && callee.hir_id == expr.hir_id + { + if self.closure_span_overlaps_error(error, *call_span) { + return false; + } + + for param in + [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at] + .into_iter() + .flatten() + { + if self.point_at_arg_if_possible( + error, + def_id, + param, + *call_hir_id, + callee.span, + None, + args, + ) + { + return true; + } + } + } + // Notably, we only point to params that are local to the + // item we're checking, since those are the ones we are able + // to look in the final `hir::PathSegment` for. Everything else + // would require a deeper search into the `qpath` than I think + // is worthwhile. + if let Some(param_to_point_at) = param_to_point_at + && self.point_at_path_if_possible(error, def_id, param_to_point_at, qpath) + { + return true; + } + } + hir::ExprKind::MethodCall(segment, receiver, args, ..) => { + for param in [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at] + .into_iter() + .flatten() + { + if self.point_at_arg_if_possible( + error, + def_id, + param, + hir_id, + segment.ident.span, + Some(receiver), + args, + ) { + return true; + } + } + if let Some(param_to_point_at) = param_to_point_at + && self.point_at_generic_if_possible(error, def_id, param_to_point_at, segment) + { + return true; + } + } + hir::ExprKind::Struct(qpath, fields, ..) => { + if let Res::Def(DefKind::Struct | DefKind::Variant, variant_def_id) = + self.typeck_results.borrow().qpath_res(qpath, hir_id) + { + for param in + [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at] + { + if let Some(param) = param + && self.point_at_field_if_possible( + error, + def_id, + param, + variant_def_id, + fields, + ) + { + return true; + } + } + } + if let Some(param_to_point_at) = param_to_point_at + && self.point_at_path_if_possible(error, def_id, param_to_point_at, qpath) + { + return true; + } + } + _ => {} + } + + false + } + + fn closure_span_overlaps_error( + &self, + error: &traits::FulfillmentError<'tcx>, + span: Span, + ) -> bool { + if let traits::FulfillmentErrorCode::CodeSelectionError( + traits::SelectionError::OutputTypeParameterMismatch(_, expected, _), + ) = error.code + && let ty::Closure(def_id, _) | ty::Generator(def_id, ..) = expected.skip_binder().self_ty().kind() + && span.overlaps(self.tcx.def_span(*def_id)) + { + true + } else { + false + } + } + + fn point_at_arg_if_possible( + &self, + error: &mut traits::FulfillmentError<'tcx>, + def_id: DefId, + param_to_point_at: ty::GenericArg<'tcx>, + call_hir_id: hir::HirId, + callee_span: Span, + receiver: Option<&'tcx hir::Expr<'tcx>>, + args: &'tcx [hir::Expr<'tcx>], + ) -> bool { + let sig = self.tcx.fn_sig(def_id).skip_binder(); + let args_referencing_param: Vec<_> = sig + .inputs() + .iter() + .enumerate() + .filter(|(_, ty)| find_param_in_ty(**ty, param_to_point_at)) + .collect(); + // If there's one field that references the given generic, great! + if let [(idx, _)] = args_referencing_param.as_slice() + && let Some(arg) = receiver + .map_or(args.get(*idx), |rcvr| if *idx == 0 { Some(rcvr) } else { args.get(*idx - 1) }) { + error.obligation.cause.span = arg.span.find_ancestor_in_same_ctxt(error.obligation.cause.span).unwrap_or(arg.span); + error.obligation.cause.map_code(|parent_code| { + ObligationCauseCode::FunctionArgumentObligation { + arg_hir_id: arg.hir_id, + call_hir_id, + parent_code, + } + }); + return true; + } else if args_referencing_param.len() > 0 { + // If more than one argument applies, then point to the callee span at least... + // We have chance to fix this up further in `point_at_generics_if_possible` + error.obligation.cause.span = callee_span; + } + + false + } + + fn point_at_field_if_possible( + &self, + error: &mut traits::FulfillmentError<'tcx>, + def_id: DefId, + param_to_point_at: ty::GenericArg<'tcx>, + variant_def_id: DefId, + expr_fields: &[hir::ExprField<'tcx>], + ) -> bool { + let def = self.tcx.adt_def(def_id); + + let identity_substs = ty::InternalSubsts::identity_for_item(self.tcx, def_id); + let fields_referencing_param: Vec<_> = def + .variant_with_id(variant_def_id) + .fields + .iter() + .filter(|field| { + let field_ty = field.ty(self.tcx, identity_substs); + find_param_in_ty(field_ty, param_to_point_at) + }) + .collect(); + + if let [field] = fields_referencing_param.as_slice() { + for expr_field in expr_fields { + // Look for the ExprField that matches the field, using the + // same rules that check_expr_struct uses for macro hygiene. + if self.tcx.adjust_ident(expr_field.ident, variant_def_id) == field.ident(self.tcx) + { + error.obligation.cause.span = expr_field + .expr + .span + .find_ancestor_in_same_ctxt(error.obligation.cause.span) + .unwrap_or(expr_field.span); + return true; + } + } + } + + false + } + + fn point_at_path_if_possible( + &self, + error: &mut traits::FulfillmentError<'tcx>, + def_id: DefId, + param: ty::GenericArg<'tcx>, + qpath: &QPath<'tcx>, + ) -> bool { + match qpath { + hir::QPath::Resolved(_, path) => { + if let Some(segment) = path.segments.last() + && self.point_at_generic_if_possible(error, def_id, param, segment) + { + return true; + } + } + hir::QPath::TypeRelative(_, segment) => { + if self.point_at_generic_if_possible(error, def_id, param, segment) { + return true; + } + } + _ => {} + } + + false + } + + fn point_at_generic_if_possible( + &self, + error: &mut traits::FulfillmentError<'tcx>, + def_id: DefId, + param_to_point_at: ty::GenericArg<'tcx>, + segment: &hir::PathSegment<'tcx>, + ) -> bool { + let own_substs = self + .tcx + .generics_of(def_id) + .own_substs(ty::InternalSubsts::identity_for_item(self.tcx, def_id)); + let Some((index, _)) = own_substs + .iter() + .filter(|arg| matches!(arg.unpack(), ty::GenericArgKind::Type(_))) + .enumerate() + .find(|(_, arg)| **arg == param_to_point_at) else { return false }; + let Some(arg) = segment + .args() + .args + .iter() + .filter(|arg| matches!(arg, hir::GenericArg::Type(_))) + .nth(index) else { return false; }; + error.obligation.cause.span = arg + .span() + .find_ancestor_in_same_ctxt(error.obligation.cause.span) + .unwrap_or(arg.span()); + true + } + + fn find_ambiguous_parameter_in>( + &self, + item_def_id: DefId, + t: T, + ) -> Option> { + struct FindAmbiguousParameter<'a, 'tcx>(&'a FnCtxt<'a, 'tcx>, DefId); + impl<'tcx> TypeVisitor<'tcx> for FindAmbiguousParameter<'_, 'tcx> { + type BreakTy = ty::GenericArg<'tcx>; + fn visit_ty(&mut self, ty: Ty<'tcx>) -> std::ops::ControlFlow { + if let Some(origin) = self.0.type_var_origin(ty) + && let TypeVariableOriginKind::TypeParameterDefinition(_, Some(def_id)) = + origin.kind + && let generics = self.0.tcx.generics_of(self.1) + && let Some(index) = generics.param_def_id_to_index(self.0.tcx, def_id) + && let Some(subst) = ty::InternalSubsts::identity_for_item(self.0.tcx, self.1) + .get(index as usize) + { + ControlFlow::Break(*subst) + } else { + ty.super_visit_with(self) + } + } + } + t.visit_with(&mut FindAmbiguousParameter(self, item_def_id)).break_value() + } + + fn label_fn_like( + &self, + err: &mut Diagnostic, + callable_def_id: Option, + callee_ty: Option>, + // A specific argument should be labeled, instead of all of them + expected_idx: Option, + is_method: bool, + ) { + let Some(mut def_id) = callable_def_id else { + return; + }; + + if let Some(assoc_item) = self.tcx.opt_associated_item(def_id) + // Possibly points at either impl or trait item, so try to get it + // to point to trait item, then get the parent. + // This parent might be an impl in the case of an inherent function, + // but the next check will fail. + && let maybe_trait_item_def_id = assoc_item.trait_item_def_id.unwrap_or(def_id) + && let maybe_trait_def_id = self.tcx.parent(maybe_trait_item_def_id) + // Just an easy way to check "trait_def_id == Fn/FnMut/FnOnce" + && let Some(call_kind) = ty::ClosureKind::from_def_id(self.tcx, maybe_trait_def_id) + && let Some(callee_ty) = callee_ty + { + let callee_ty = callee_ty.peel_refs(); + match *callee_ty.kind() { + ty::Param(param) => { + let param = + self.tcx.generics_of(self.body_id.owner).type_param(¶m, self.tcx); + if param.kind.is_synthetic() { + // if it's `impl Fn() -> ..` then just fall down to the def-id based logic + def_id = param.def_id; + } else { + // Otherwise, find the predicate that makes this generic callable, + // and point at that. + let instantiated = self + .tcx + .explicit_predicates_of(self.body_id.owner) + .instantiate_identity(self.tcx); + // FIXME(compiler-errors): This could be problematic if something has two + // fn-like predicates with different args, but callable types really never + // do that, so it's OK. + for (predicate, span) in + std::iter::zip(instantiated.predicates, instantiated.spans) + { + if let ty::PredicateKind::Trait(pred) = predicate.kind().skip_binder() + && pred.self_ty().peel_refs() == callee_ty + && ty::ClosureKind::from_def_id(self.tcx, pred.def_id()).is_some() + { + err.span_note(span, "callable defined here"); + return; + } + } + } + } + ty::Opaque(new_def_id, _) + | ty::Closure(new_def_id, _) + | ty::FnDef(new_def_id, _) => { + def_id = new_def_id; + } + _ => { + // Look for a user-provided impl of a `Fn` trait, and point to it. + let new_def_id = self.probe(|_| { + let trait_ref = ty::TraitRef::new( + call_kind.to_def_id(self.tcx), + self.tcx.mk_substs( + [ + ty::GenericArg::from(callee_ty), + self.next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::MiscVariable, + span: rustc_span::DUMMY_SP, + }) + .into(), + ] + .into_iter(), + ), + ); + let obligation = traits::Obligation::new( + traits::ObligationCause::dummy(), + self.param_env, + ty::Binder::dummy(ty::TraitPredicate { + trait_ref, + constness: ty::BoundConstness::NotConst, + polarity: ty::ImplPolarity::Positive, + }), + ); + match SelectionContext::new(&self).select(&obligation) { + Ok(Some(traits::ImplSource::UserDefined(impl_source))) => { + Some(impl_source.impl_def_id) + } + _ => None, + } + }); + if let Some(new_def_id) = new_def_id { + def_id = new_def_id; + } else { + return; + } + } + } + } + + if let Some(def_span) = self.tcx.def_ident_span(def_id) && !def_span.is_dummy() { + let mut spans: MultiSpan = def_span.into(); + + let params = self + .tcx + .hir() + .get_if_local(def_id) + .and_then(|node| node.body_id()) + .into_iter() + .flat_map(|id| self.tcx.hir().body(id).params) + .skip(if is_method { 1 } else { 0 }); + + for (_, param) in params + .into_iter() + .enumerate() + .filter(|(idx, _)| expected_idx.map_or(true, |expected_idx| expected_idx == *idx)) + { + spans.push_span_label(param.span, ""); + } + + let def_kind = self.tcx.def_kind(def_id); + err.span_note(spans, &format!("{} defined here", def_kind.descr(def_id))); + } else if let Some(hir::Node::Expr(e)) = self.tcx.hir().get_if_local(def_id) + && let hir::ExprKind::Closure(hir::Closure { body, .. }) = &e.kind + { + let param = expected_idx + .and_then(|expected_idx| self.tcx.hir().body(*body).params.get(expected_idx)); + let (kind, span) = if let Some(param) = param { + ("closure parameter", param.span) + } else { + ("closure", self.tcx.def_span(def_id)) + }; + err.span_note(span, &format!("{} defined here", kind)); + } else { + let def_kind = self.tcx.def_kind(def_id); + err.span_note( + self.tcx.def_span(def_id), + &format!("{} defined here", def_kind.descr(def_id)), + ); + } + } +} + +fn find_param_in_ty<'tcx>(ty: Ty<'tcx>, param_to_point_at: ty::GenericArg<'tcx>) -> bool { + let mut walk = ty.walk(); + while let Some(arg) = walk.next() { + if arg == param_to_point_at { + return true; + } else if let ty::GenericArgKind::Type(ty) = arg.unpack() + && let ty::Projection(..) = ty.kind() + { + // This logic may seem a bit strange, but typically when + // we have a projection type in a function signature, the + // argument that's being passed into that signature is + // not actually constraining that projection's substs in + // a meaningful way. So we skip it, and see improvements + // in some UI tests. + walk.skip_current_subtree(); + } + } + false +} diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs new file mode 100644 index 000000000..0c600daf4 --- /dev/null +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs @@ -0,0 +1,312 @@ +mod _impl; +mod arg_matrix; +mod checks; +mod suggestions; + +pub use _impl::*; +pub use suggestions::*; + +use crate::coercion::DynamicCoerceMany; +use crate::{Diverges, EnclosingBreakables, Inherited, UnsafetyState}; +use rustc_hir as hir; +use rustc_hir::def_id::DefId; +use rustc_hir_analysis::astconv::AstConv; +use rustc_infer::infer; +use rustc_infer::infer::error_reporting::TypeErrCtxt; +use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; +use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind}; +use rustc_middle::ty::subst::GenericArgKind; +use rustc_middle::ty::visit::TypeVisitable; +use rustc_middle::ty::{self, Const, Ty, TyCtxt}; +use rustc_session::Session; +use rustc_span::symbol::Ident; +use rustc_span::{self, Span}; +use rustc_trait_selection::traits::{ObligationCause, ObligationCauseCode}; + +use std::cell::{Cell, RefCell}; +use std::ops::Deref; + +/// The `FnCtxt` stores type-checking context needed to type-check bodies of +/// functions, closures, and `const`s, including performing type inference +/// with [`InferCtxt`]. +/// +/// This is in contrast to [`ItemCtxt`], which is used to type-check item *signatures* +/// and thus does not perform type inference. +/// +/// See [`ItemCtxt`]'s docs for more. +/// +/// [`ItemCtxt`]: rustc_hir_analysis::collect::ItemCtxt +/// [`InferCtxt`]: infer::InferCtxt +pub struct FnCtxt<'a, 'tcx> { + pub(super) body_id: hir::HirId, + + /// The parameter environment used for proving trait obligations + /// in this function. This can change when we descend into + /// closures (as they bring new things into scope), hence it is + /// not part of `Inherited` (as of the time of this writing, + /// closures do not yet change the environment, but they will + /// eventually). + pub(super) param_env: ty::ParamEnv<'tcx>, + + /// Number of errors that had been reported when we started + /// checking this function. On exit, if we find that *more* errors + /// have been reported, we will skip regionck and other work that + /// expects the types within the function to be consistent. + // FIXME(matthewjasper) This should not exist, and it's not correct + // if type checking is run in parallel. + err_count_on_creation: usize, + + /// If `Some`, this stores coercion information for returned + /// expressions. If `None`, this is in a context where return is + /// inappropriate, such as a const expression. + /// + /// This is a `RefCell`, which means that we + /// can track all the return expressions and then use them to + /// compute a useful coercion from the set, similar to a match + /// expression or other branching context. You can use methods + /// like `expected_ty` to access the declared return type (if + /// any). + pub(super) ret_coercion: Option>>, + + /// Used exclusively to reduce cost of advanced evaluation used for + /// more helpful diagnostics. + pub(super) in_tail_expr: bool, + + /// First span of a return site that we find. Used in error messages. + pub(super) ret_coercion_span: Cell>, + + pub(super) resume_yield_tys: Option<(Ty<'tcx>, Ty<'tcx>)>, + + pub(super) ps: Cell, + + /// Whether the last checked node generates a divergence (e.g., + /// `return` will set this to `Always`). In general, when entering + /// an expression or other node in the tree, the initial value + /// indicates whether prior parts of the containing expression may + /// have diverged. It is then typically set to `Maybe` (and the + /// old value remembered) for processing the subparts of the + /// current expression. As each subpart is processed, they may set + /// the flag to `Always`, etc. Finally, at the end, we take the + /// result and "union" it with the original value, so that when we + /// return the flag indicates if any subpart of the parent + /// expression (up to and including this part) has diverged. So, + /// if you read it after evaluating a subexpression `X`, the value + /// you get indicates whether any subexpression that was + /// evaluating up to and including `X` diverged. + /// + /// We currently use this flag only for diagnostic purposes: + /// + /// - To warn about unreachable code: if, after processing a + /// sub-expression but before we have applied the effects of the + /// current node, we see that the flag is set to `Always`, we + /// can issue a warning. This corresponds to something like + /// `foo(return)`; we warn on the `foo()` expression. (We then + /// update the flag to `WarnedAlways` to suppress duplicate + /// reports.) Similarly, if we traverse to a fresh statement (or + /// tail expression) from an `Always` setting, we will issue a + /// warning. This corresponds to something like `{return; + /// foo();}` or `{return; 22}`, where we would warn on the + /// `foo()` or `22`. + /// + /// An expression represents dead code if, after checking it, + /// the diverges flag is set to something other than `Maybe`. + pub(super) diverges: Cell, + + /// Whether any child nodes have any type errors. + pub(super) has_errors: Cell, + + pub(super) enclosing_breakables: RefCell>, + + pub(super) inh: &'a Inherited<'tcx>, + + /// True if the function or closure's return type is known before + /// entering the function/closure, i.e. if the return type is + /// either given explicitly or inferred from, say, an `Fn*` trait + /// bound. Used for diagnostic purposes only. + pub(super) return_type_pre_known: bool, + + /// True if the return type has an Opaque type + pub(super) return_type_has_opaque: bool, +} + +impl<'a, 'tcx> FnCtxt<'a, 'tcx> { + pub fn new( + inh: &'a Inherited<'tcx>, + param_env: ty::ParamEnv<'tcx>, + body_id: hir::HirId, + ) -> FnCtxt<'a, 'tcx> { + FnCtxt { + body_id, + param_env, + err_count_on_creation: inh.tcx.sess.err_count(), + ret_coercion: None, + in_tail_expr: false, + ret_coercion_span: Cell::new(None), + resume_yield_tys: None, + ps: Cell::new(UnsafetyState::function(hir::Unsafety::Normal, hir::CRATE_HIR_ID)), + diverges: Cell::new(Diverges::Maybe), + has_errors: Cell::new(false), + enclosing_breakables: RefCell::new(EnclosingBreakables { + stack: Vec::new(), + by_id: Default::default(), + }), + inh, + return_type_pre_known: true, + return_type_has_opaque: false, + } + } + + pub fn cause(&self, span: Span, code: ObligationCauseCode<'tcx>) -> ObligationCause<'tcx> { + ObligationCause::new(span, self.body_id, code) + } + + pub fn misc(&self, span: Span) -> ObligationCause<'tcx> { + self.cause(span, ObligationCauseCode::MiscObligation) + } + + pub fn sess(&self) -> &Session { + &self.tcx.sess + } + + /// Creates an `TypeErrCtxt` with a reference to the in-progress + /// `TypeckResults` which is used for diagnostics. + /// Use [`InferCtxt::err_ctxt`] to start one without a `TypeckResults`. + /// + /// [`InferCtxt::err_ctxt`]: infer::InferCtxt::err_ctxt + pub fn err_ctxt(&'a self) -> TypeErrCtxt<'a, 'tcx> { + TypeErrCtxt { infcx: &self.infcx, typeck_results: Some(self.typeck_results.borrow()) } + } + + pub fn errors_reported_since_creation(&self) -> bool { + self.tcx.sess.err_count() > self.err_count_on_creation + } +} + +impl<'a, 'tcx> Deref for FnCtxt<'a, 'tcx> { + type Target = Inherited<'tcx>; + fn deref(&self) -> &Self::Target { + &self.inh + } +} + +impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> { + fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { + self.tcx + } + + fn item_def_id(&self) -> Option { + None + } + + fn get_type_parameter_bounds( + &self, + _: Span, + def_id: DefId, + _: Ident, + ) -> ty::GenericPredicates<'tcx> { + let tcx = self.tcx; + let item_def_id = tcx.hir().ty_param_owner(def_id.expect_local()); + let generics = tcx.generics_of(item_def_id); + let index = generics.param_def_id_to_index[&def_id]; + ty::GenericPredicates { + parent: None, + predicates: tcx.arena.alloc_from_iter( + self.param_env.caller_bounds().iter().filter_map(|predicate| { + match predicate.kind().skip_binder() { + ty::PredicateKind::Trait(data) if data.self_ty().is_param(index) => { + // HACK(eddyb) should get the original `Span`. + let span = tcx.def_span(def_id); + Some((predicate, span)) + } + _ => None, + } + }), + ), + } + } + + fn re_infer(&self, def: Option<&ty::GenericParamDef>, span: Span) -> Option> { + let v = match def { + Some(def) => infer::EarlyBoundRegion(span, def.name), + None => infer::MiscVariable(span), + }; + Some(self.next_region_var(v)) + } + + fn allow_ty_infer(&self) -> bool { + true + } + + fn ty_infer(&self, param: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> { + if let Some(param) = param { + if let GenericArgKind::Type(ty) = self.var_for_def(span, param).unpack() { + return ty; + } + unreachable!() + } else { + self.next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::TypeInference, + span, + }) + } + } + + fn ct_infer( + &self, + ty: Ty<'tcx>, + param: Option<&ty::GenericParamDef>, + span: Span, + ) -> Const<'tcx> { + if let Some(param) = param { + if let GenericArgKind::Const(ct) = self.var_for_def(span, param).unpack() { + return ct; + } + unreachable!() + } else { + self.next_const_var( + ty, + ConstVariableOrigin { kind: ConstVariableOriginKind::ConstInference, span }, + ) + } + } + + fn projected_ty_from_poly_trait_ref( + &self, + span: Span, + item_def_id: DefId, + item_segment: &hir::PathSegment<'_>, + poly_trait_ref: ty::PolyTraitRef<'tcx>, + ) -> Ty<'tcx> { + let trait_ref = self.replace_bound_vars_with_fresh_vars( + span, + infer::LateBoundRegionConversionTime::AssocTypeProjection(item_def_id), + poly_trait_ref, + ); + + let item_substs = >::create_substs_for_associated_item( + self, + span, + item_def_id, + item_segment, + trait_ref.substs, + ); + + self.tcx().mk_projection(item_def_id, item_substs) + } + + fn normalize_ty(&self, span: Span, ty: Ty<'tcx>) -> Ty<'tcx> { + if ty.has_escaping_bound_vars() { + ty // FIXME: normalization and escaping regions + } else { + self.normalize_associated_types_in(span, ty) + } + } + + fn set_tainted_by_errors(&self) { + self.infcx.set_tainted_by_errors() + } + + fn record_ty(&self, hir_id: hir::HirId, ty: Ty<'tcx>, _span: Span) { + self.write_ty(hir_id, ty) + } +} diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs new file mode 100644 index 000000000..4db9c56f9 --- /dev/null +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs @@ -0,0 +1,1250 @@ +use super::FnCtxt; + +use crate::errors::{AddReturnTypeSuggestion, ExpectedReturnTypeLabel}; +use rustc_ast::util::parser::{ExprPrecedence, PREC_POSTFIX}; +use rustc_errors::{Applicability, Diagnostic, MultiSpan}; +use rustc_hir as hir; +use rustc_hir::def::{CtorOf, DefKind}; +use rustc_hir::lang_items::LangItem; +use rustc_hir::{ + Expr, ExprKind, GenericBound, Node, Path, QPath, Stmt, StmtKind, TyKind, WherePredicate, +}; +use rustc_hir_analysis::astconv::AstConv; +use rustc_infer::infer::{self, TyCtxtInferExt}; +use rustc_infer::traits::{self, StatementAsExpression}; +use rustc_middle::lint::in_external_macro; +use rustc_middle::ty::{self, Binder, IsSuggestable, ToPredicate, Ty}; +use rustc_session::errors::ExprParenthesesNeeded; +use rustc_span::symbol::sym; +use rustc_span::Span; +use rustc_trait_selection::infer::InferCtxtExt; +use rustc_trait_selection::traits::error_reporting::DefIdOrName; +use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _; + +impl<'a, 'tcx> FnCtxt<'a, 'tcx> { + pub(in super::super) fn suggest_semicolon_at_end(&self, span: Span, err: &mut Diagnostic) { + err.span_suggestion_short( + span.shrink_to_hi(), + "consider using a semicolon here", + ";", + Applicability::MachineApplicable, + ); + } + + /// On implicit return expressions with mismatched types, provides the following suggestions: + /// + /// - Points out the method's return type as the reason for the expected type. + /// - Possible missing semicolon. + /// - Possible missing return type if the return type is the default, and not `fn main()`. + pub fn suggest_mismatched_types_on_tail( + &self, + err: &mut Diagnostic, + expr: &'tcx hir::Expr<'tcx>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + blk_id: hir::HirId, + ) -> bool { + let expr = expr.peel_drop_temps(); + self.suggest_missing_semicolon(err, expr, expected, false); + let mut pointing_at_return_type = false; + if let Some((fn_decl, can_suggest)) = self.get_fn_decl(blk_id) { + let fn_id = self.tcx.hir().get_return_block(blk_id).unwrap(); + pointing_at_return_type = self.suggest_missing_return_type( + err, + &fn_decl, + expected, + found, + can_suggest, + fn_id, + ); + self.suggest_missing_break_or_return_expr( + err, expr, &fn_decl, expected, found, blk_id, fn_id, + ); + } + pointing_at_return_type + } + + /// When encountering an fn-like type, try accessing the output of the type + /// and suggesting calling it if it satisfies a predicate (i.e. if the + /// output has a method or a field): + /// ```compile_fail,E0308 + /// fn foo(x: usize) -> usize { x } + /// let x: usize = foo; // suggest calling the `foo` function: `foo(42)` + /// ``` + pub(crate) fn suggest_fn_call( + &self, + err: &mut Diagnostic, + expr: &hir::Expr<'_>, + found: Ty<'tcx>, + can_satisfy: impl FnOnce(Ty<'tcx>) -> bool, + ) -> bool { + let Some((def_id_or_name, output, inputs)) = self.extract_callable_info(expr, found) + else { return false; }; + if can_satisfy(output) { + let (sugg_call, mut applicability) = match inputs.len() { + 0 => ("".to_string(), Applicability::MachineApplicable), + 1..=4 => ( + inputs + .iter() + .map(|ty| { + if ty.is_suggestable(self.tcx, false) { + format!("/* {ty} */") + } else { + "/* value */".to_string() + } + }) + .collect::>() + .join(", "), + Applicability::HasPlaceholders, + ), + _ => ("/* ... */".to_string(), Applicability::HasPlaceholders), + }; + + let msg = match def_id_or_name { + DefIdOrName::DefId(def_id) => match self.tcx.def_kind(def_id) { + DefKind::Ctor(CtorOf::Struct, _) => "construct this tuple struct".to_string(), + DefKind::Ctor(CtorOf::Variant, _) => "construct this tuple variant".to_string(), + kind => format!("call this {}", kind.descr(def_id)), + }, + DefIdOrName::Name(name) => format!("call this {name}"), + }; + + let sugg = match expr.kind { + hir::ExprKind::Call(..) + | hir::ExprKind::Path(..) + | hir::ExprKind::Index(..) + | hir::ExprKind::Lit(..) => { + vec![(expr.span.shrink_to_hi(), format!("({sugg_call})"))] + } + hir::ExprKind::Closure { .. } => { + // Might be `{ expr } || { bool }` + applicability = Applicability::MaybeIncorrect; + vec![ + (expr.span.shrink_to_lo(), "(".to_string()), + (expr.span.shrink_to_hi(), format!(")({sugg_call})")), + ] + } + _ => { + vec![ + (expr.span.shrink_to_lo(), "(".to_string()), + (expr.span.shrink_to_hi(), format!(")({sugg_call})")), + ] + } + }; + + err.multipart_suggestion_verbose( + format!("use parentheses to {msg}"), + sugg, + applicability, + ); + return true; + } + false + } + + /// Extracts information about a callable type for diagnostics. This is a + /// heuristic -- it doesn't necessarily mean that a type is always callable, + /// because the callable type must also be well-formed to be called. + pub(in super::super) fn extract_callable_info( + &self, + expr: &Expr<'_>, + found: Ty<'tcx>, + ) -> Option<(DefIdOrName, Ty<'tcx>, Vec>)> { + // Autoderef is useful here because sometimes we box callables, etc. + let Some((def_id_or_name, output, inputs)) = self.autoderef(expr.span, found).silence_errors().find_map(|(found, _)| { + match *found.kind() { + ty::FnPtr(fn_sig) => + Some((DefIdOrName::Name("function pointer"), fn_sig.output(), fn_sig.inputs())), + ty::FnDef(def_id, _) => { + let fn_sig = found.fn_sig(self.tcx); + Some((DefIdOrName::DefId(def_id), fn_sig.output(), fn_sig.inputs())) + } + ty::Closure(def_id, substs) => { + let fn_sig = substs.as_closure().sig(); + Some((DefIdOrName::DefId(def_id), fn_sig.output(), fn_sig.inputs().map_bound(|inputs| &inputs[1..]))) + } + ty::Opaque(def_id, substs) => { + self.tcx.bound_item_bounds(def_id).subst(self.tcx, substs).iter().find_map(|pred| { + if let ty::PredicateKind::Projection(proj) = pred.kind().skip_binder() + && Some(proj.projection_ty.item_def_id) == self.tcx.lang_items().fn_once_output() + // args tuple will always be substs[1] + && let ty::Tuple(args) = proj.projection_ty.substs.type_at(1).kind() + { + Some(( + DefIdOrName::DefId(def_id), + pred.kind().rebind(proj.term.ty().unwrap()), + pred.kind().rebind(args.as_slice()), + )) + } else { + None + } + }) + } + ty::Dynamic(data, _, ty::Dyn) => { + data.iter().find_map(|pred| { + if let ty::ExistentialPredicate::Projection(proj) = pred.skip_binder() + && Some(proj.item_def_id) == self.tcx.lang_items().fn_once_output() + // for existential projection, substs are shifted over by 1 + && let ty::Tuple(args) = proj.substs.type_at(0).kind() + { + Some(( + DefIdOrName::Name("trait object"), + pred.rebind(proj.term.ty().unwrap()), + pred.rebind(args.as_slice()), + )) + } else { + None + } + }) + } + ty::Param(param) => { + let def_id = self.tcx.generics_of(self.body_id.owner).type_param(¶m, self.tcx).def_id; + self.tcx.predicates_of(self.body_id.owner).predicates.iter().find_map(|(pred, _)| { + if let ty::PredicateKind::Projection(proj) = pred.kind().skip_binder() + && Some(proj.projection_ty.item_def_id) == self.tcx.lang_items().fn_once_output() + && proj.projection_ty.self_ty() == found + // args tuple will always be substs[1] + && let ty::Tuple(args) = proj.projection_ty.substs.type_at(1).kind() + { + Some(( + DefIdOrName::DefId(def_id), + pred.kind().rebind(proj.term.ty().unwrap()), + pred.kind().rebind(args.as_slice()), + )) + } else { + None + } + }) + } + _ => None, + } + }) else { return None; }; + + let output = self.replace_bound_vars_with_fresh_vars(expr.span, infer::FnCall, output); + let inputs = inputs + .skip_binder() + .iter() + .map(|ty| { + self.replace_bound_vars_with_fresh_vars( + expr.span, + infer::FnCall, + inputs.rebind(*ty), + ) + }) + .collect(); + + // We don't want to register any extra obligations, which should be + // implied by wf, but also because that would possibly result in + // erroneous errors later on. + let infer::InferOk { value: output, obligations: _ } = + self.normalize_associated_types_in_as_infer_ok(expr.span, output); + + if output.is_ty_var() { None } else { Some((def_id_or_name, output, inputs)) } + } + + pub fn suggest_two_fn_call( + &self, + err: &mut Diagnostic, + lhs_expr: &'tcx hir::Expr<'tcx>, + lhs_ty: Ty<'tcx>, + rhs_expr: &'tcx hir::Expr<'tcx>, + rhs_ty: Ty<'tcx>, + can_satisfy: impl FnOnce(Ty<'tcx>, Ty<'tcx>) -> bool, + ) -> bool { + let Some((_, lhs_output_ty, lhs_inputs)) = self.extract_callable_info(lhs_expr, lhs_ty) + else { return false; }; + let Some((_, rhs_output_ty, rhs_inputs)) = self.extract_callable_info(rhs_expr, rhs_ty) + else { return false; }; + + if can_satisfy(lhs_output_ty, rhs_output_ty) { + let mut sugg = vec![]; + let mut applicability = Applicability::MachineApplicable; + + for (expr, inputs) in [(lhs_expr, lhs_inputs), (rhs_expr, rhs_inputs)] { + let (sugg_call, this_applicability) = match inputs.len() { + 0 => ("".to_string(), Applicability::MachineApplicable), + 1..=4 => ( + inputs + .iter() + .map(|ty| { + if ty.is_suggestable(self.tcx, false) { + format!("/* {ty} */") + } else { + "/* value */".to_string() + } + }) + .collect::>() + .join(", "), + Applicability::HasPlaceholders, + ), + _ => ("/* ... */".to_string(), Applicability::HasPlaceholders), + }; + + applicability = applicability.max(this_applicability); + + match expr.kind { + hir::ExprKind::Call(..) + | hir::ExprKind::Path(..) + | hir::ExprKind::Index(..) + | hir::ExprKind::Lit(..) => { + sugg.extend([(expr.span.shrink_to_hi(), format!("({sugg_call})"))]); + } + hir::ExprKind::Closure { .. } => { + // Might be `{ expr } || { bool }` + applicability = Applicability::MaybeIncorrect; + sugg.extend([ + (expr.span.shrink_to_lo(), "(".to_string()), + (expr.span.shrink_to_hi(), format!(")({sugg_call})")), + ]); + } + _ => { + sugg.extend([ + (expr.span.shrink_to_lo(), "(".to_string()), + (expr.span.shrink_to_hi(), format!(")({sugg_call})")), + ]); + } + } + } + + err.multipart_suggestion_verbose( + format!("use parentheses to call these"), + sugg, + applicability, + ); + + true + } else { + false + } + } + + pub fn suggest_deref_ref_or_into( + &self, + err: &mut Diagnostic, + expr: &hir::Expr<'tcx>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>, + ) -> bool { + let expr = expr.peel_blocks(); + if let Some((sp, msg, suggestion, applicability, verbose, annotation)) = + self.check_ref(expr, found, expected) + { + if verbose { + err.span_suggestion_verbose(sp, &msg, suggestion, applicability); + } else { + err.span_suggestion(sp, &msg, suggestion, applicability); + } + if annotation { + let suggest_annotation = match expr.peel_drop_temps().kind { + hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Not, _) => "&", + hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Mut, _) => "&mut ", + _ => return true, + }; + let mut tuple_indexes = Vec::new(); + let mut expr_id = expr.hir_id; + for (parent_id, node) in self.tcx.hir().parent_iter(expr.hir_id) { + match node { + Node::Expr(&Expr { kind: ExprKind::Tup(subs), .. }) => { + tuple_indexes.push( + subs.iter() + .enumerate() + .find(|(_, sub_expr)| sub_expr.hir_id == expr_id) + .unwrap() + .0, + ); + expr_id = parent_id; + } + Node::Local(local) => { + if let Some(mut ty) = local.ty { + while let Some(index) = tuple_indexes.pop() { + match ty.kind { + TyKind::Tup(tys) => ty = &tys[index], + _ => return true, + } + } + let annotation_span = ty.span; + err.span_suggestion( + annotation_span.with_hi(annotation_span.lo()), + format!("alternatively, consider changing the type annotation"), + suggest_annotation, + Applicability::MaybeIncorrect, + ); + } + break; + } + _ => break, + } + } + } + return true; + } else if self.suggest_else_fn_with_closure(err, expr, found, expected) { + return true; + } else if self.suggest_fn_call(err, expr, found, |output| self.can_coerce(output, expected)) + && let ty::FnDef(def_id, ..) = &found.kind() + && let Some(sp) = self.tcx.hir().span_if_local(*def_id) + { + err.span_label(sp, format!("{found} defined here")); + return true; + } else if self.check_for_cast(err, expr, found, expected, expected_ty_expr) { + return true; + } else { + let methods = self.get_conversion_methods(expr.span, expected, found, expr.hir_id); + if !methods.is_empty() { + let mut suggestions = methods.iter() + .filter_map(|conversion_method| { + let receiver_method_ident = expr.method_ident(); + if let Some(method_ident) = receiver_method_ident + && method_ident.name == conversion_method.name + { + return None // do not suggest code that is already there (#53348) + } + + let method_call_list = [sym::to_vec, sym::to_string]; + let mut sugg = if let ExprKind::MethodCall(receiver_method, ..) = expr.kind + && receiver_method.ident.name == sym::clone + && method_call_list.contains(&conversion_method.name) + // If receiver is `.clone()` and found type has one of those methods, + // we guess that the user wants to convert from a slice type (`&[]` or `&str`) + // to an owned type (`Vec` or `String`). These conversions clone internally, + // so we remove the user's `clone` call. + { + vec![( + receiver_method.ident.span, + conversion_method.name.to_string() + )] + } else if expr.precedence().order() + < ExprPrecedence::MethodCall.order() + { + vec![ + (expr.span.shrink_to_lo(), "(".to_string()), + (expr.span.shrink_to_hi(), format!(").{}()", conversion_method.name)), + ] + } else { + vec![(expr.span.shrink_to_hi(), format!(".{}()", conversion_method.name))] + }; + let struct_pat_shorthand_field = self.maybe_get_struct_pattern_shorthand_field(expr); + if let Some(name) = struct_pat_shorthand_field { + sugg.insert( + 0, + (expr.span.shrink_to_lo(), format!("{}: ", name)), + ); + } + Some(sugg) + }) + .peekable(); + if suggestions.peek().is_some() { + err.multipart_suggestions( + "try using a conversion method", + suggestions, + Applicability::MaybeIncorrect, + ); + return true; + } + } else if let ty::Adt(found_adt, found_substs) = found.kind() + && self.tcx.is_diagnostic_item(sym::Option, found_adt.did()) + && let ty::Adt(expected_adt, expected_substs) = expected.kind() + && self.tcx.is_diagnostic_item(sym::Option, expected_adt.did()) + && let ty::Ref(_, inner_ty, _) = expected_substs.type_at(0).kind() + && inner_ty.is_str() + { + let ty = found_substs.type_at(0); + let mut peeled = ty; + let mut ref_cnt = 0; + while let ty::Ref(_, inner, _) = peeled.kind() { + peeled = *inner; + ref_cnt += 1; + } + if let ty::Adt(adt, _) = peeled.kind() + && self.tcx.is_diagnostic_item(sym::String, adt.did()) + { + err.span_suggestion_verbose( + expr.span.shrink_to_hi(), + "try converting the passed type into a `&str`", + format!(".map(|x| &*{}x)", "*".repeat(ref_cnt)), + Applicability::MaybeIncorrect, + ); + return true; + } + } + } + + false + } + + /// When encountering the expected boxed value allocated in the stack, suggest allocating it + /// in the heap by calling `Box::new()`. + pub(in super::super) fn suggest_boxing_when_appropriate( + &self, + err: &mut Diagnostic, + expr: &hir::Expr<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + ) -> bool { + if self.tcx.hir().is_inside_const_context(expr.hir_id) { + // Do not suggest `Box::new` in const context. + return false; + } + if !expected.is_box() || found.is_box() { + return false; + } + let boxed_found = self.tcx.mk_box(found); + if self.can_coerce(boxed_found, expected) { + err.multipart_suggestion( + "store this in the heap by calling `Box::new`", + vec![ + (expr.span.shrink_to_lo(), "Box::new(".to_string()), + (expr.span.shrink_to_hi(), ")".to_string()), + ], + Applicability::MachineApplicable, + ); + err.note( + "for more on the distinction between the stack and the heap, read \ + https://doc.rust-lang.org/book/ch15-01-box.html, \ + https://doc.rust-lang.org/rust-by-example/std/box.html, and \ + https://doc.rust-lang.org/std/boxed/index.html", + ); + true + } else { + false + } + } + + /// When encountering a closure that captures variables, where a FnPtr is expected, + /// suggest a non-capturing closure + pub(in super::super) fn suggest_no_capture_closure( + &self, + err: &mut Diagnostic, + expected: Ty<'tcx>, + found: Ty<'tcx>, + ) -> bool { + if let (ty::FnPtr(_), ty::Closure(def_id, _)) = (expected.kind(), found.kind()) { + if let Some(upvars) = self.tcx.upvars_mentioned(*def_id) { + // Report upto four upvars being captured to reduce the amount error messages + // reported back to the user. + let spans_and_labels = upvars + .iter() + .take(4) + .map(|(var_hir_id, upvar)| { + let var_name = self.tcx.hir().name(*var_hir_id).to_string(); + let msg = format!("`{}` captured here", var_name); + (upvar.span, msg) + }) + .collect::>(); + + let mut multi_span: MultiSpan = + spans_and_labels.iter().map(|(sp, _)| *sp).collect::>().into(); + for (sp, label) in spans_and_labels { + multi_span.push_span_label(sp, label); + } + err.span_note( + multi_span, + "closures can only be coerced to `fn` types if they do not capture any variables" + ); + return true; + } + } + false + } + + /// When encountering an `impl Future` where `BoxFuture` is expected, suggest `Box::pin`. + #[instrument(skip(self, err))] + pub(in super::super) fn suggest_calling_boxed_future_when_appropriate( + &self, + err: &mut Diagnostic, + expr: &hir::Expr<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + ) -> bool { + // Handle #68197. + + if self.tcx.hir().is_inside_const_context(expr.hir_id) { + // Do not suggest `Box::new` in const context. + return false; + } + let pin_did = self.tcx.lang_items().pin_type(); + // This guards the `unwrap` and `mk_box` below. + if pin_did.is_none() || self.tcx.lang_items().owned_box().is_none() { + return false; + } + let box_found = self.tcx.mk_box(found); + let pin_box_found = self.tcx.mk_lang_item(box_found, LangItem::Pin).unwrap(); + let pin_found = self.tcx.mk_lang_item(found, LangItem::Pin).unwrap(); + match expected.kind() { + ty::Adt(def, _) if Some(def.did()) == pin_did => { + if self.can_coerce(pin_box_found, expected) { + debug!("can coerce {:?} to {:?}, suggesting Box::pin", pin_box_found, expected); + match found.kind() { + ty::Adt(def, _) if def.is_box() => { + err.help("use `Box::pin`"); + } + _ => { + err.multipart_suggestion( + "you need to pin and box this expression", + vec![ + (expr.span.shrink_to_lo(), "Box::pin(".to_string()), + (expr.span.shrink_to_hi(), ")".to_string()), + ], + Applicability::MaybeIncorrect, + ); + } + } + true + } else if self.can_coerce(pin_found, expected) { + match found.kind() { + ty::Adt(def, _) if def.is_box() => { + err.help("use `Box::pin`"); + true + } + _ => false, + } + } else { + false + } + } + ty::Adt(def, _) if def.is_box() && self.can_coerce(box_found, expected) => { + // Check if the parent expression is a call to Pin::new. If it + // is and we were expecting a Box, ergo Pin>, we + // can suggest Box::pin. + let parent = self.tcx.hir().get_parent_node(expr.hir_id); + let Some(Node::Expr(Expr { kind: ExprKind::Call(fn_name, _), .. })) = self.tcx.hir().find(parent) else { + return false; + }; + match fn_name.kind { + ExprKind::Path(QPath::TypeRelative( + hir::Ty { + kind: TyKind::Path(QPath::Resolved(_, Path { res: recv_ty, .. })), + .. + }, + method, + )) if recv_ty.opt_def_id() == pin_did && method.ident.name == sym::new => { + err.span_suggestion( + fn_name.span, + "use `Box::pin` to pin and box this expression", + "Box::pin", + Applicability::MachineApplicable, + ); + true + } + _ => false, + } + } + _ => false, + } + } + + /// A common error is to forget to add a semicolon at the end of a block, e.g., + /// + /// ```compile_fail,E0308 + /// # fn bar_that_returns_u32() -> u32 { 4 } + /// fn foo() { + /// bar_that_returns_u32() + /// } + /// ``` + /// + /// This routine checks if the return expression in a block would make sense on its own as a + /// statement and the return type has been left as default or has been specified as `()`. If so, + /// it suggests adding a semicolon. + /// + /// If the expression is the expression of a closure without block (`|| expr`), a + /// block is needed to be added too (`|| { expr; }`). This is denoted by `needs_block`. + pub fn suggest_missing_semicolon( + &self, + err: &mut Diagnostic, + expression: &'tcx hir::Expr<'tcx>, + expected: Ty<'tcx>, + needs_block: bool, + ) { + if expected.is_unit() { + // `BlockTailExpression` only relevant if the tail expr would be + // useful on its own. + match expression.kind { + ExprKind::Call(..) + | ExprKind::MethodCall(..) + | ExprKind::Loop(..) + | ExprKind::If(..) + | ExprKind::Match(..) + | ExprKind::Block(..) + if expression.can_have_side_effects() + // If the expression is from an external macro, then do not suggest + // adding a semicolon, because there's nowhere to put it. + // See issue #81943. + && !in_external_macro(self.tcx.sess, expression.span) => + { + if needs_block { + err.multipart_suggestion( + "consider using a semicolon here", + vec![ + (expression.span.shrink_to_lo(), "{ ".to_owned()), + (expression.span.shrink_to_hi(), "; }".to_owned()), + ], + Applicability::MachineApplicable, + ); + } else { + err.span_suggestion( + expression.span.shrink_to_hi(), + "consider using a semicolon here", + ";", + Applicability::MachineApplicable, + ); + } + } + _ => (), + } + } + } + + /// A possible error is to forget to add a return type that is needed: + /// + /// ```compile_fail,E0308 + /// # fn bar_that_returns_u32() -> u32 { 4 } + /// fn foo() { + /// bar_that_returns_u32() + /// } + /// ``` + /// + /// This routine checks if the return type is left as default, the method is not part of an + /// `impl` block and that it isn't the `main` method. If so, it suggests setting the return + /// type. + pub(in super::super) fn suggest_missing_return_type( + &self, + err: &mut Diagnostic, + fn_decl: &hir::FnDecl<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + can_suggest: bool, + fn_id: hir::HirId, + ) -> bool { + let found = + self.resolve_numeric_literals_with_default(self.resolve_vars_if_possible(found)); + // Only suggest changing the return type for methods that + // haven't set a return type at all (and aren't `fn main()` or an impl). + match &fn_decl.output { + &hir::FnRetTy::DefaultReturn(span) if expected.is_unit() && !can_suggest => { + // `fn main()` must return `()`, do not suggest changing return type + err.subdiagnostic(ExpectedReturnTypeLabel::Unit { span }); + return true; + } + &hir::FnRetTy::DefaultReturn(span) if expected.is_unit() => { + if found.is_suggestable(self.tcx, false) { + err.subdiagnostic(AddReturnTypeSuggestion::Add { span, found: found.to_string() }); + return true; + } else if let ty::Closure(_, substs) = found.kind() + // FIXME(compiler-errors): Get better at printing binders... + && let closure = substs.as_closure() + && closure.sig().is_suggestable(self.tcx, false) + { + err.subdiagnostic(AddReturnTypeSuggestion::Add { span, found: closure.print_as_impl_trait().to_string() }); + return true; + } else { + // FIXME: if `found` could be `impl Iterator` we should suggest that. + err.subdiagnostic(AddReturnTypeSuggestion::MissingHere { span }); + return true + } + } + &hir::FnRetTy::Return(ref ty) => { + // Only point to return type if the expected type is the return type, as if they + // are not, the expectation must have been caused by something else. + debug!("suggest_missing_return_type: return type {:?} node {:?}", ty, ty.kind); + let span = ty.span; + let ty = >::ast_ty_to_ty(self, ty); + debug!("suggest_missing_return_type: return type {:?}", ty); + debug!("suggest_missing_return_type: expected type {:?}", ty); + let bound_vars = self.tcx.late_bound_vars(fn_id); + let ty = Binder::bind_with_vars(ty, bound_vars); + let ty = self.normalize_associated_types_in(span, ty); + let ty = self.tcx.erase_late_bound_regions(ty); + if self.can_coerce(expected, ty) { + err.subdiagnostic(ExpectedReturnTypeLabel::Other { span, expected }); + self.try_suggest_return_impl_trait(err, expected, ty, fn_id); + return true; + } + } + _ => {} + } + false + } + + /// check whether the return type is a generic type with a trait bound + /// only suggest this if the generic param is not present in the arguments + /// if this is true, hint them towards changing the return type to `impl Trait` + /// ```compile_fail,E0308 + /// fn cant_name_it u32>() -> T { + /// || 3 + /// } + /// ``` + fn try_suggest_return_impl_trait( + &self, + err: &mut Diagnostic, + expected: Ty<'tcx>, + found: Ty<'tcx>, + fn_id: hir::HirId, + ) { + // Only apply the suggestion if: + // - the return type is a generic parameter + // - the generic param is not used as a fn param + // - the generic param has at least one bound + // - the generic param doesn't appear in any other bounds where it's not the Self type + // Suggest: + // - Changing the return type to be `impl ` + + debug!("try_suggest_return_impl_trait, expected = {:?}, found = {:?}", expected, found); + + let ty::Param(expected_ty_as_param) = expected.kind() else { return }; + + let fn_node = self.tcx.hir().find(fn_id); + + let Some(hir::Node::Item(hir::Item { + kind: + hir::ItemKind::Fn( + hir::FnSig { decl: hir::FnDecl { inputs: fn_parameters, output: fn_return, .. }, .. }, + hir::Generics { params, predicates, .. }, + _body_id, + ), + .. + })) = fn_node else { return }; + + if params.get(expected_ty_as_param.index as usize).is_none() { + return; + }; + + // get all where BoundPredicates here, because they are used in to cases below + let where_predicates = predicates + .iter() + .filter_map(|p| match p { + WherePredicate::BoundPredicate(hir::WhereBoundPredicate { + bounds, + bounded_ty, + .. + }) => { + // FIXME: Maybe these calls to `ast_ty_to_ty` can be removed (and the ones below) + let ty = >::ast_ty_to_ty(self, bounded_ty); + Some((ty, bounds)) + } + _ => None, + }) + .map(|(ty, bounds)| match ty.kind() { + ty::Param(param_ty) if param_ty == expected_ty_as_param => Ok(Some(bounds)), + // check whether there is any predicate that contains our `T`, like `Option: Send` + _ => match ty.contains(expected) { + true => Err(()), + false => Ok(None), + }, + }) + .collect::, _>>(); + + let Ok(where_predicates) = where_predicates else { return }; + + // now get all predicates in the same types as the where bounds, so we can chain them + let predicates_from_where = + where_predicates.iter().flatten().flat_map(|bounds| bounds.iter()); + + // extract all bounds from the source code using their spans + let all_matching_bounds_strs = predicates_from_where + .filter_map(|bound| match bound { + GenericBound::Trait(_, _) => { + self.tcx.sess.source_map().span_to_snippet(bound.span()).ok() + } + _ => None, + }) + .collect::>(); + + if all_matching_bounds_strs.len() == 0 { + return; + } + + let all_bounds_str = all_matching_bounds_strs.join(" + "); + + let ty_param_used_in_fn_params = fn_parameters.iter().any(|param| { + let ty = >::ast_ty_to_ty(self, param); + matches!(ty.kind(), ty::Param(fn_param_ty_param) if expected_ty_as_param == fn_param_ty_param) + }); + + if ty_param_used_in_fn_params { + return; + } + + err.span_suggestion( + fn_return.span(), + "consider using an impl return type", + format!("impl {}", all_bounds_str), + Applicability::MaybeIncorrect, + ); + } + + pub(in super::super) fn suggest_missing_break_or_return_expr( + &self, + err: &mut Diagnostic, + expr: &'tcx hir::Expr<'tcx>, + fn_decl: &hir::FnDecl<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + id: hir::HirId, + fn_id: hir::HirId, + ) { + if !expected.is_unit() { + return; + } + let found = self.resolve_vars_with_obligations(found); + + let in_loop = self.is_loop(id) + || self.tcx.hir().parent_iter(id).any(|(parent_id, _)| self.is_loop(parent_id)); + + let in_local_statement = self.is_local_statement(id) + || self + .tcx + .hir() + .parent_iter(id) + .any(|(parent_id, _)| self.is_local_statement(parent_id)); + + if in_loop && in_local_statement { + err.multipart_suggestion( + "you might have meant to break the loop with this value", + vec![ + (expr.span.shrink_to_lo(), "break ".to_string()), + (expr.span.shrink_to_hi(), ";".to_string()), + ], + Applicability::MaybeIncorrect, + ); + return; + } + + if let hir::FnRetTy::Return(ty) = fn_decl.output { + let ty = >::ast_ty_to_ty(self, ty); + let bound_vars = self.tcx.late_bound_vars(fn_id); + let ty = self.tcx.erase_late_bound_regions(Binder::bind_with_vars(ty, bound_vars)); + let ty = self.normalize_associated_types_in(expr.span, ty); + let ty = match self.tcx.asyncness(fn_id.owner) { + hir::IsAsync::Async => { + let infcx = self.tcx.infer_ctxt().build(); + infcx + .get_impl_future_output_ty(ty) + .unwrap_or_else(|| { + span_bug!( + fn_decl.output.span(), + "failed to get output type of async function" + ) + }) + .skip_binder() + } + hir::IsAsync::NotAsync => ty, + }; + if self.can_coerce(found, ty) { + err.multipart_suggestion( + "you might have meant to return this value", + vec![ + (expr.span.shrink_to_lo(), "return ".to_string()), + (expr.span.shrink_to_hi(), ";".to_string()), + ], + Applicability::MaybeIncorrect, + ); + } + } + } + + pub(in super::super) fn suggest_missing_parentheses( + &self, + err: &mut Diagnostic, + expr: &hir::Expr<'_>, + ) -> bool { + let sp = self.tcx.sess.source_map().start_point(expr.span); + if let Some(sp) = self.tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp) { + // `{ 42 } &&x` (#61475) or `{ 42 } && if x { 1 } else { 0 }` + err.subdiagnostic(ExprParenthesesNeeded::surrounding(*sp)); + true + } else { + false + } + } + + /// Given an expression type mismatch, peel any `&` expressions until we get to + /// a block expression, and then suggest replacing the braces with square braces + /// if it was possibly mistaken array syntax. + pub(crate) fn suggest_block_to_brackets_peeling_refs( + &self, + diag: &mut Diagnostic, + mut expr: &hir::Expr<'_>, + mut expr_ty: Ty<'tcx>, + mut expected_ty: Ty<'tcx>, + ) -> bool { + loop { + match (&expr.kind, expr_ty.kind(), expected_ty.kind()) { + ( + hir::ExprKind::AddrOf(_, _, inner_expr), + ty::Ref(_, inner_expr_ty, _), + ty::Ref(_, inner_expected_ty, _), + ) => { + expr = *inner_expr; + expr_ty = *inner_expr_ty; + expected_ty = *inner_expected_ty; + } + (hir::ExprKind::Block(blk, _), _, _) => { + self.suggest_block_to_brackets(diag, *blk, expr_ty, expected_ty); + break true; + } + _ => break false, + } + } + } + + pub(crate) fn suggest_copied_or_cloned( + &self, + diag: &mut Diagnostic, + expr: &hir::Expr<'_>, + expr_ty: Ty<'tcx>, + expected_ty: Ty<'tcx>, + ) -> bool { + let ty::Adt(adt_def, substs) = expr_ty.kind() else { return false; }; + let ty::Adt(expected_adt_def, expected_substs) = expected_ty.kind() else { return false; }; + if adt_def != expected_adt_def { + return false; + } + + let mut suggest_copied_or_cloned = || { + let expr_inner_ty = substs.type_at(0); + let expected_inner_ty = expected_substs.type_at(0); + if let ty::Ref(_, ty, hir::Mutability::Not) = expr_inner_ty.kind() + && self.can_eq(self.param_env, *ty, expected_inner_ty).is_ok() + { + let def_path = self.tcx.def_path_str(adt_def.did()); + if self.type_is_copy_modulo_regions(self.param_env, *ty, expr.span) { + diag.span_suggestion_verbose( + expr.span.shrink_to_hi(), + format!( + "use `{def_path}::copied` to copy the value inside the `{def_path}`" + ), + ".copied()", + Applicability::MachineApplicable, + ); + return true; + } else if let Some(clone_did) = self.tcx.lang_items().clone_trait() + && rustc_trait_selection::traits::type_known_to_meet_bound_modulo_regions( + self, + self.param_env, + *ty, + clone_did, + expr.span + ) + { + diag.span_suggestion_verbose( + expr.span.shrink_to_hi(), + format!( + "use `{def_path}::cloned` to clone the value inside the `{def_path}`" + ), + ".cloned()", + Applicability::MachineApplicable, + ); + return true; + } + } + false + }; + + if let Some(result_did) = self.tcx.get_diagnostic_item(sym::Result) + && adt_def.did() == result_did + // Check that the error types are equal + && self.can_eq(self.param_env, substs.type_at(1), expected_substs.type_at(1)).is_ok() + { + return suggest_copied_or_cloned(); + } else if let Some(option_did) = self.tcx.get_diagnostic_item(sym::Option) + && adt_def.did() == option_did + { + return suggest_copied_or_cloned(); + } + + false + } + + pub(crate) fn suggest_into( + &self, + diag: &mut Diagnostic, + expr: &hir::Expr<'_>, + expr_ty: Ty<'tcx>, + expected_ty: Ty<'tcx>, + ) -> bool { + let expr = expr.peel_blocks(); + + // We have better suggestions for scalar interconversions... + if expr_ty.is_scalar() && expected_ty.is_scalar() { + return false; + } + + // Don't suggest turning a block into another type (e.g. `{}.into()`) + if matches!(expr.kind, hir::ExprKind::Block(..)) { + return false; + } + + // We'll later suggest `.as_ref` when noting the type error, + // so skip if we will suggest that instead. + if self.err_ctxt().should_suggest_as_ref(expected_ty, expr_ty).is_some() { + return false; + } + + if let Some(into_def_id) = self.tcx.get_diagnostic_item(sym::Into) + && self.predicate_must_hold_modulo_regions(&traits::Obligation::new( + self.misc(expr.span), + self.param_env, + ty::Binder::dummy(ty::TraitRef { + def_id: into_def_id, + substs: self.tcx.mk_substs_trait(expr_ty, &[expected_ty.into()]), + }) + .to_poly_trait_predicate() + .to_predicate(self.tcx), + )) + { + let sugg = if expr.precedence().order() >= PREC_POSTFIX { + vec![(expr.span.shrink_to_hi(), ".into()".to_owned())] + } else { + vec![(expr.span.shrink_to_lo(), "(".to_owned()), (expr.span.shrink_to_hi(), ").into()".to_owned())] + }; + diag.multipart_suggestion( + format!("call `Into::into` on this expression to convert `{expr_ty}` into `{expected_ty}`"), + sugg, + Applicability::MaybeIncorrect + ); + return true; + } + + false + } + + /// Suggest wrapping the block in square brackets instead of curly braces + /// in case the block was mistaken array syntax, e.g. `{ 1 }` -> `[ 1 ]`. + pub(crate) fn suggest_block_to_brackets( + &self, + diag: &mut Diagnostic, + blk: &hir::Block<'_>, + blk_ty: Ty<'tcx>, + expected_ty: Ty<'tcx>, + ) { + if let ty::Slice(elem_ty) | ty::Array(elem_ty, _) = expected_ty.kind() { + if self.can_coerce(blk_ty, *elem_ty) + && blk.stmts.is_empty() + && blk.rules == hir::BlockCheckMode::DefaultBlock + { + let source_map = self.tcx.sess.source_map(); + if let Ok(snippet) = source_map.span_to_snippet(blk.span) { + if snippet.starts_with('{') && snippet.ends_with('}') { + diag.multipart_suggestion_verbose( + "to create an array, use square brackets instead of curly braces", + vec![ + ( + blk.span + .shrink_to_lo() + .with_hi(rustc_span::BytePos(blk.span.lo().0 + 1)), + "[".to_string(), + ), + ( + blk.span + .shrink_to_hi() + .with_lo(rustc_span::BytePos(blk.span.hi().0 - 1)), + "]".to_string(), + ), + ], + Applicability::MachineApplicable, + ); + } + } + } + } + } + + fn is_loop(&self, id: hir::HirId) -> bool { + let node = self.tcx.hir().get(id); + matches!(node, Node::Expr(Expr { kind: ExprKind::Loop(..), .. })) + } + + fn is_local_statement(&self, id: hir::HirId) -> bool { + let node = self.tcx.hir().get(id); + matches!(node, Node::Stmt(Stmt { kind: StmtKind::Local(..), .. })) + } + + /// Suggest that `&T` was cloned instead of `T` because `T` does not implement `Clone`, + /// which is a side-effect of autoref. + pub(crate) fn note_type_is_not_clone( + &self, + diag: &mut Diagnostic, + expected_ty: Ty<'tcx>, + found_ty: Ty<'tcx>, + expr: &hir::Expr<'_>, + ) { + let hir::ExprKind::MethodCall(segment, callee_expr, &[], _) = expr.kind else { return; }; + let Some(clone_trait_did) = self.tcx.lang_items().clone_trait() else { return; }; + let ty::Ref(_, pointee_ty, _) = found_ty.kind() else { return }; + let results = self.typeck_results.borrow(); + // First, look for a `Clone::clone` call + if segment.ident.name == sym::clone + && results.type_dependent_def_id(expr.hir_id).map_or( + false, + |did| { + let assoc_item = self.tcx.associated_item(did); + assoc_item.container == ty::AssocItemContainer::TraitContainer + && assoc_item.container_id(self.tcx) == clone_trait_did + }, + ) + // If that clone call hasn't already dereferenced the self type (i.e. don't give this + // diagnostic in cases where we have `(&&T).clone()` and we expect `T`). + && !results.expr_adjustments(callee_expr).iter().any(|adj| matches!(adj.kind, ty::adjustment::Adjust::Deref(..))) + // Check that we're in fact trying to clone into the expected type + && self.can_coerce(*pointee_ty, expected_ty) + // And the expected type doesn't implement `Clone` + && !self.predicate_must_hold_considering_regions(&traits::Obligation { + cause: traits::ObligationCause::dummy(), + param_env: self.param_env, + recursion_depth: 0, + predicate: ty::Binder::dummy(ty::TraitRef { + def_id: clone_trait_did, + substs: self.tcx.mk_substs([expected_ty.into()].iter()), + }) + .without_const() + .to_predicate(self.tcx), + }) + { + diag.span_note( + callee_expr.span, + &format!( + "`{expected_ty}` does not implement `Clone`, so `{found_ty}` was cloned instead" + ), + ); + } + } + + /// A common error is to add an extra semicolon: + /// + /// ```compile_fail,E0308 + /// fn foo() -> usize { + /// 22; + /// } + /// ``` + /// + /// This routine checks if the final statement in a block is an + /// expression with an explicit semicolon whose type is compatible + /// with `expected_ty`. If so, it suggests removing the semicolon. + pub(crate) fn consider_removing_semicolon( + &self, + blk: &'tcx hir::Block<'tcx>, + expected_ty: Ty<'tcx>, + err: &mut Diagnostic, + ) -> bool { + if let Some((span_semi, boxed)) = self.err_ctxt().could_remove_semicolon(blk, expected_ty) { + if let StatementAsExpression::NeedsBoxing = boxed { + err.span_suggestion_verbose( + span_semi, + "consider removing this semicolon and boxing the expression", + "", + Applicability::HasPlaceholders, + ); + } else { + err.span_suggestion_short( + span_semi, + "remove this semicolon to return this value", + "", + Applicability::MachineApplicable, + ); + } + true + } else { + false + } + } +} -- cgit v1.2.3