diff options
Diffstat (limited to 'compiler/rustc_typeck/src/check/expr.rs')
| -rw-r--r-- | compiler/rustc_typeck/src/check/expr.rs | 2824 |
1 files changed, 2824 insertions, 0 deletions
diff --git a/compiler/rustc_typeck/src/check/expr.rs b/compiler/rustc_typeck/src/check/expr.rs new file mode 100644 index 000000000..6e97b0bf2 --- /dev/null +++ b/compiler/rustc_typeck/src/check/expr.rs @@ -0,0 +1,2824 @@ +//! Type checking expressions. +//! +//! See `mod.rs` for more context on type checking in general. + +use crate::astconv::AstConv as _; +use crate::check::cast; +use crate::check::coercion::CoerceMany; +use crate::check::fatally_break_rust; +use crate::check::method::SelfSource; +use crate::check::report_unexpected_variant_res; +use crate::check::BreakableCtxt; +use crate::check::Diverges; +use crate::check::DynamicCoerceMany; +use crate::check::Expectation::{self, ExpectCastableToType, ExpectHasType, NoExpectation}; +use crate::check::FnCtxt; +use crate::check::Needs; +use crate::check::TupleArgumentsFlag::DontTupleArguments; +use crate::errors::{ + FieldMultiplySpecifiedInInitializer, FunctionalRecordUpdateOnNonStruct, + YieldExprOutsideOfGenerator, +}; +use crate::type_error_struct; + +use super::suggest_call_constructor; +use crate::errors::{AddressOfTemporaryTaken, ReturnStmtOutsideOfFnBody, StructExprNonExhaustive}; +use rustc_ast as ast; +use rustc_data_structures::fx::FxHashMap; +use rustc_data_structures::stack::ensure_sufficient_stack; +use rustc_errors::{ + pluralize, struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, DiagnosticId, + EmissionGuarantee, ErrorGuaranteed, +}; +use rustc_hir as hir; +use rustc_hir::def::{CtorKind, DefKind, Res}; +use rustc_hir::def_id::DefId; +use rustc_hir::intravisit::Visitor; +use rustc_hir::lang_items::LangItem; +use rustc_hir::{Closure, ExprKind, HirId, QPath}; +use rustc_infer::infer; +use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; +use rustc_infer::infer::InferOk; +use rustc_infer::traits::ObligationCause; +use rustc_middle::middle::stability; +use rustc_middle::ty::adjustment::{Adjust, Adjustment, AllowTwoPhase}; +use rustc_middle::ty::error::TypeError::FieldMisMatch; +use rustc_middle::ty::subst::SubstsRef; +use rustc_middle::ty::{self, AdtKind, DefIdTree, Ty, TypeVisitable}; +use rustc_session::parse::feature_err; +use rustc_span::hygiene::DesugaringKind; +use rustc_span::lev_distance::find_best_match_for_name; +use rustc_span::source_map::{Span, Spanned}; +use rustc_span::symbol::{kw, sym, Ident, Symbol}; +use rustc_span::{BytePos, Pos}; +use rustc_target::spec::abi::Abi::RustIntrinsic; +use rustc_trait_selection::infer::InferCtxtExt; +use rustc_trait_selection::traits::{self, ObligationCauseCode}; + +impl<'a, 'tcx> FnCtxt<'a, 'tcx> { + fn check_expr_eq_type(&self, expr: &'tcx hir::Expr<'tcx>, expected: Ty<'tcx>) { + let ty = self.check_expr_with_hint(expr, expected); + self.demand_eqtype(expr.span, expected, ty); + } + + pub fn check_expr_has_type_or_error( + &self, + expr: &'tcx hir::Expr<'tcx>, + expected: Ty<'tcx>, + extend_err: impl FnMut(&mut Diagnostic), + ) -> Ty<'tcx> { + self.check_expr_meets_expectation_or_error(expr, ExpectHasType(expected), extend_err) + } + + fn check_expr_meets_expectation_or_error( + &self, + expr: &'tcx hir::Expr<'tcx>, + expected: Expectation<'tcx>, + mut extend_err: impl FnMut(&mut Diagnostic), + ) -> Ty<'tcx> { + let expected_ty = expected.to_option(&self).unwrap_or(self.tcx.types.bool); + let mut ty = self.check_expr_with_expectation(expr, expected); + + // While we don't allow *arbitrary* coercions here, we *do* allow + // coercions from ! to `expected`. + if ty.is_never() { + if let Some(adjustments) = self.typeck_results.borrow().adjustments().get(expr.hir_id) { + self.tcx().sess.delay_span_bug( + expr.span, + "expression with never type wound up being adjusted", + ); + return if let [Adjustment { kind: Adjust::NeverToAny, target }] = &adjustments[..] { + target.to_owned() + } else { + self.tcx().ty_error() + }; + } + + let adj_ty = self.next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::AdjustmentType, + span: expr.span, + }); + self.apply_adjustments( + expr, + vec![Adjustment { kind: Adjust::NeverToAny, target: adj_ty }], + ); + ty = adj_ty; + } + + if let Some(mut err) = self.demand_suptype_diag(expr.span, expected_ty, ty) { + let expr = expr.peel_drop_temps(); + self.suggest_deref_ref_or_into(&mut err, expr, expected_ty, ty, None); + extend_err(&mut err); + err.emit(); + } + ty + } + + pub(super) fn check_expr_coercable_to_type( + &self, + expr: &'tcx hir::Expr<'tcx>, + expected: Ty<'tcx>, + expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>, + ) -> Ty<'tcx> { + let ty = self.check_expr_with_hint(expr, expected); + // checks don't need two phase + self.demand_coerce(expr, ty, expected, expected_ty_expr, AllowTwoPhase::No) + } + + pub(super) fn check_expr_with_hint( + &self, + expr: &'tcx hir::Expr<'tcx>, + expected: Ty<'tcx>, + ) -> Ty<'tcx> { + self.check_expr_with_expectation(expr, ExpectHasType(expected)) + } + + fn check_expr_with_expectation_and_needs( + &self, + expr: &'tcx hir::Expr<'tcx>, + expected: Expectation<'tcx>, + needs: Needs, + ) -> Ty<'tcx> { + let ty = self.check_expr_with_expectation(expr, expected); + + // If the expression is used in a place whether mutable place is required + // e.g. LHS of assignment, perform the conversion. + if let Needs::MutPlace = needs { + self.convert_place_derefs_to_mutable(expr); + } + + ty + } + + pub(super) fn check_expr(&self, expr: &'tcx hir::Expr<'tcx>) -> Ty<'tcx> { + self.check_expr_with_expectation(expr, NoExpectation) + } + + pub(super) fn check_expr_with_needs( + &self, + expr: &'tcx hir::Expr<'tcx>, + needs: Needs, + ) -> Ty<'tcx> { + self.check_expr_with_expectation_and_needs(expr, NoExpectation, needs) + } + + /// Invariant: + /// If an expression has any sub-expressions that result in a type error, + /// inspecting that expression's type with `ty.references_error()` will return + /// true. Likewise, if an expression is known to diverge, inspecting its + /// type with `ty::type_is_bot` will return true (n.b.: since Rust is + /// strict, _|_ can appear in the type of an expression that does not, + /// itself, diverge: for example, fn() -> _|_.) + /// Note that inspecting a type's structure *directly* may expose the fact + /// that there are actually multiple representations for `Error`, so avoid + /// that when err needs to be handled differently. + #[instrument(skip(self, expr), level = "debug")] + pub(super) fn check_expr_with_expectation( + &self, + expr: &'tcx hir::Expr<'tcx>, + expected: Expectation<'tcx>, + ) -> Ty<'tcx> { + self.check_expr_with_expectation_and_args(expr, expected, &[]) + } + + /// Same as `check_expr_with_expectation`, but allows us to pass in the arguments of a + /// `ExprKind::Call` when evaluating its callee when it is an `ExprKind::Path`. + pub(super) fn check_expr_with_expectation_and_args( + &self, + expr: &'tcx hir::Expr<'tcx>, + expected: Expectation<'tcx>, + args: &'tcx [hir::Expr<'tcx>], + ) -> Ty<'tcx> { + if self.tcx().sess.verbose() { + // make this code only run with -Zverbose because it is probably slow + if let Ok(lint_str) = self.tcx.sess.source_map().span_to_snippet(expr.span) { + if !lint_str.contains('\n') { + debug!("expr text: {lint_str}"); + } else { + let mut lines = lint_str.lines(); + if let Some(line0) = lines.next() { + let remaining_lines = lines.count(); + debug!("expr text: {line0}"); + debug!("expr text: ...(and {remaining_lines} more lines)"); + } + } + } + } + + // True if `expr` is a `Try::from_ok(())` that is a result of desugaring a try block + // without the final expr (e.g. `try { return; }`). We don't want to generate an + // unreachable_code lint for it since warnings for autogenerated code are confusing. + let is_try_block_generated_unit_expr = match expr.kind { + ExprKind::Call(_, args) if expr.span.is_desugaring(DesugaringKind::TryBlock) => { + args.len() == 1 && args[0].span.is_desugaring(DesugaringKind::TryBlock) + } + + _ => false, + }; + + // Warn for expressions after diverging siblings. + if !is_try_block_generated_unit_expr { + self.warn_if_unreachable(expr.hir_id, expr.span, "expression"); + } + + // 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); + + let ty = ensure_sufficient_stack(|| match &expr.kind { + hir::ExprKind::Path( + qpath @ hir::QPath::Resolved(..) | qpath @ hir::QPath::TypeRelative(..), + ) => self.check_expr_path(qpath, expr, args), + _ => self.check_expr_kind(expr, expected), + }); + + // Warn for non-block expressions with diverging children. + match expr.kind { + ExprKind::Block(..) + | ExprKind::If(..) + | ExprKind::Let(..) + | ExprKind::Loop(..) + | ExprKind::Match(..) => {} + // If `expr` is a result of desugaring the try block and is an ok-wrapped + // diverging expression (e.g. it arose from desugaring of `try { return }`), + // we skip issuing a warning because it is autogenerated code. + ExprKind::Call(..) if expr.span.is_desugaring(DesugaringKind::TryBlock) => {} + ExprKind::Call(callee, _) => self.warn_if_unreachable(expr.hir_id, callee.span, "call"), + ExprKind::MethodCall(segment, ..) => { + self.warn_if_unreachable(expr.hir_id, segment.ident.span, "call") + } + _ => self.warn_if_unreachable(expr.hir_id, expr.span, "expression"), + } + + // Any expression that produces a value of type `!` must have diverged + if ty.is_never() { + self.diverges.set(self.diverges.get() | Diverges::always(expr.span)); + } + + // Record the type, which applies it effects. + // We need to do this after the warning above, so that + // we don't warn for the diverging expression itself. + self.write_ty(expr.hir_id, ty); + + // 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); + + debug!("type of {} is...", self.tcx.hir().node_to_string(expr.hir_id)); + debug!("... {:?}, expected is {:?}", ty, expected); + + ty + } + + #[instrument(skip(self, expr), level = "debug")] + fn check_expr_kind( + &self, + expr: &'tcx hir::Expr<'tcx>, + expected: Expectation<'tcx>, + ) -> Ty<'tcx> { + trace!("expr={:#?}", expr); + + let tcx = self.tcx; + match expr.kind { + ExprKind::Box(subexpr) => self.check_expr_box(subexpr, expected), + ExprKind::Lit(ref lit) => self.check_lit(&lit, expected), + ExprKind::Binary(op, lhs, rhs) => self.check_binop(expr, op, lhs, rhs, expected), + ExprKind::Assign(lhs, rhs, span) => { + self.check_expr_assign(expr, expected, lhs, rhs, span) + } + ExprKind::AssignOp(op, lhs, rhs) => { + self.check_binop_assign(expr, op, lhs, rhs, expected) + } + ExprKind::Unary(unop, oprnd) => self.check_expr_unary(unop, oprnd, expected, expr), + ExprKind::AddrOf(kind, mutbl, oprnd) => { + self.check_expr_addr_of(kind, mutbl, oprnd, expected, expr) + } + ExprKind::Path(QPath::LangItem(lang_item, _, hir_id)) => { + self.check_lang_item_path(lang_item, expr, hir_id) + } + ExprKind::Path(ref qpath) => self.check_expr_path(qpath, expr, &[]), + ExprKind::InlineAsm(asm) => { + // We defer some asm checks as we may not have resolved the input and output types yet (they may still be infer vars). + self.deferred_asm_checks.borrow_mut().push((asm, expr.hir_id)); + self.check_expr_asm(asm) + } + ExprKind::Break(destination, ref expr_opt) => { + self.check_expr_break(destination, expr_opt.as_deref(), expr) + } + ExprKind::Continue(destination) => { + if destination.target_id.is_ok() { + tcx.types.never + } else { + // There was an error; make type-check fail. + tcx.ty_error() + } + } + ExprKind::Ret(ref expr_opt) => self.check_expr_return(expr_opt.as_deref(), expr), + ExprKind::Let(let_expr) => self.check_expr_let(let_expr), + ExprKind::Loop(body, _, source, _) => { + self.check_expr_loop(body, source, expected, expr) + } + ExprKind::Match(discrim, arms, match_src) => { + self.check_match(expr, &discrim, arms, expected, match_src) + } + ExprKind::Closure(&Closure { capture_clause, fn_decl, body, movability, .. }) => { + self.check_expr_closure(expr, capture_clause, &fn_decl, body, movability, expected) + } + ExprKind::Block(body, _) => self.check_block_with_expected(&body, expected), + ExprKind::Call(callee, args) => self.check_call(expr, &callee, args, expected), + ExprKind::MethodCall(segment, args, _) => { + self.check_method_call(expr, segment, args, expected) + } + ExprKind::Cast(e, t) => self.check_expr_cast(e, t, expr), + ExprKind::Type(e, t) => { + let ty = self.to_ty_saving_user_provided_ty(&t); + self.check_expr_eq_type(&e, ty); + ty + } + ExprKind::If(cond, then_expr, opt_else_expr) => { + self.check_then_else(cond, then_expr, opt_else_expr, expr.span, expected) + } + ExprKind::DropTemps(e) => self.check_expr_with_expectation(e, expected), + ExprKind::Array(args) => self.check_expr_array(args, expected, expr), + ExprKind::ConstBlock(ref anon_const) => { + self.check_expr_const_block(anon_const, expected, expr) + } + ExprKind::Repeat(element, ref count) => { + self.check_expr_repeat(element, count, expected, expr) + } + ExprKind::Tup(elts) => self.check_expr_tuple(elts, expected, expr), + ExprKind::Struct(qpath, fields, ref base_expr) => { + self.check_expr_struct(expr, expected, qpath, fields, base_expr) + } + ExprKind::Field(base, field) => self.check_field(expr, &base, field), + ExprKind::Index(base, idx) => self.check_expr_index(base, idx, expr), + ExprKind::Yield(value, ref src) => self.check_expr_yield(value, expr, src), + hir::ExprKind::Err => tcx.ty_error(), + } + } + + fn check_expr_box(&self, expr: &'tcx hir::Expr<'tcx>, expected: Expectation<'tcx>) -> Ty<'tcx> { + let expected_inner = expected.to_option(self).map_or(NoExpectation, |ty| match ty.kind() { + ty::Adt(def, _) if def.is_box() => Expectation::rvalue_hint(self, ty.boxed_ty()), + _ => NoExpectation, + }); + let referent_ty = self.check_expr_with_expectation(expr, expected_inner); + self.require_type_is_sized(referent_ty, expr.span, traits::SizedBoxType); + self.tcx.mk_box(referent_ty) + } + + fn check_expr_unary( + &self, + unop: hir::UnOp, + oprnd: &'tcx hir::Expr<'tcx>, + expected: Expectation<'tcx>, + expr: &'tcx hir::Expr<'tcx>, + ) -> Ty<'tcx> { + let tcx = self.tcx; + let expected_inner = match unop { + hir::UnOp::Not | hir::UnOp::Neg => expected, + hir::UnOp::Deref => NoExpectation, + }; + let mut oprnd_t = self.check_expr_with_expectation(&oprnd, expected_inner); + + if !oprnd_t.references_error() { + oprnd_t = self.structurally_resolved_type(expr.span, oprnd_t); + match unop { + hir::UnOp::Deref => { + if let Some(ty) = self.lookup_derefing(expr, oprnd, oprnd_t) { + oprnd_t = ty; + } else { + let mut err = type_error_struct!( + tcx.sess, + expr.span, + oprnd_t, + E0614, + "type `{oprnd_t}` cannot be dereferenced", + ); + let sp = tcx.sess.source_map().start_point(expr.span); + if let Some(sp) = + tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp) + { + tcx.sess.parse_sess.expr_parentheses_needed(&mut err, *sp); + } + err.emit(); + oprnd_t = tcx.ty_error(); + } + } + hir::UnOp::Not => { + let result = self.check_user_unop(expr, oprnd_t, unop, expected_inner); + // If it's builtin, we can reuse the type, this helps inference. + if !(oprnd_t.is_integral() || *oprnd_t.kind() == ty::Bool) { + oprnd_t = result; + } + } + hir::UnOp::Neg => { + let result = self.check_user_unop(expr, oprnd_t, unop, expected_inner); + // If it's builtin, we can reuse the type, this helps inference. + if !oprnd_t.is_numeric() { + oprnd_t = result; + } + } + } + } + oprnd_t + } + + fn check_expr_addr_of( + &self, + kind: hir::BorrowKind, + mutbl: hir::Mutability, + oprnd: &'tcx hir::Expr<'tcx>, + expected: Expectation<'tcx>, + expr: &'tcx hir::Expr<'tcx>, + ) -> Ty<'tcx> { + let hint = expected.only_has_type(self).map_or(NoExpectation, |ty| { + match ty.kind() { + ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => { + if oprnd.is_syntactic_place_expr() { + // Places may legitimately have unsized types. + // For example, dereferences of a fat pointer and + // the last field of a struct can be unsized. + ExpectHasType(*ty) + } else { + Expectation::rvalue_hint(self, *ty) + } + } + _ => NoExpectation, + } + }); + let ty = + self.check_expr_with_expectation_and_needs(&oprnd, hint, Needs::maybe_mut_place(mutbl)); + + let tm = ty::TypeAndMut { ty, mutbl }; + match kind { + _ if tm.ty.references_error() => self.tcx.ty_error(), + hir::BorrowKind::Raw => { + self.check_named_place_expr(oprnd); + self.tcx.mk_ptr(tm) + } + hir::BorrowKind::Ref => { + // Note: at this point, we cannot say what the best lifetime + // is to use for resulting pointer. We want to use the + // shortest lifetime possible so as to avoid spurious borrowck + // errors. Moreover, the longest lifetime will depend on the + // precise details of the value whose address is being taken + // (and how long it is valid), which we don't know yet until + // type inference is complete. + // + // Therefore, here we simply generate a region variable. The + // region inferencer will then select a suitable value. + // Finally, borrowck will infer the value of the region again, + // this time with enough precision to check that the value + // whose address was taken can actually be made to live as long + // as it needs to live. + let region = self.next_region_var(infer::AddrOfRegion(expr.span)); + self.tcx.mk_ref(region, tm) + } + } + } + + /// Does this expression refer to a place that either: + /// * Is based on a local or static. + /// * Contains a dereference + /// Note that the adjustments for the children of `expr` should already + /// have been resolved. + fn check_named_place_expr(&self, oprnd: &'tcx hir::Expr<'tcx>) { + let is_named = oprnd.is_place_expr(|base| { + // Allow raw borrows if there are any deref adjustments. + // + // const VAL: (i32,) = (0,); + // const REF: &(i32,) = &(0,); + // + // &raw const VAL.0; // ERROR + // &raw const REF.0; // OK, same as &raw const (*REF).0; + // + // This is maybe too permissive, since it allows + // `let u = &raw const Box::new((1,)).0`, which creates an + // immediately dangling raw pointer. + self.typeck_results + .borrow() + .adjustments() + .get(base.hir_id) + .map_or(false, |x| x.iter().any(|adj| matches!(adj.kind, Adjust::Deref(_)))) + }); + if !is_named { + self.tcx.sess.emit_err(AddressOfTemporaryTaken { span: oprnd.span }); + } + } + + fn check_lang_item_path( + &self, + lang_item: hir::LangItem, + expr: &'tcx hir::Expr<'tcx>, + hir_id: Option<hir::HirId>, + ) -> Ty<'tcx> { + self.resolve_lang_item_path(lang_item, expr.span, expr.hir_id, hir_id).1 + } + + pub(crate) fn check_expr_path( + &self, + qpath: &'tcx hir::QPath<'tcx>, + expr: &'tcx hir::Expr<'tcx>, + args: &'tcx [hir::Expr<'tcx>], + ) -> Ty<'tcx> { + let tcx = self.tcx; + let (res, opt_ty, segs) = + self.resolve_ty_and_res_fully_qualified_call(qpath, expr.hir_id, expr.span); + let ty = match res { + Res::Err => { + self.set_tainted_by_errors(); + tcx.ty_error() + } + Res::Def(DefKind::Ctor(_, CtorKind::Fictive), _) => { + report_unexpected_variant_res(tcx, res, qpath, expr.span); + tcx.ty_error() + } + _ => self.instantiate_value_path(segs, opt_ty, res, expr.span, expr.hir_id).0, + }; + + if let ty::FnDef(did, ..) = *ty.kind() { + let fn_sig = ty.fn_sig(tcx); + if tcx.fn_sig(did).abi() == RustIntrinsic && tcx.item_name(did) == sym::transmute { + let from = fn_sig.inputs().skip_binder()[0]; + let to = fn_sig.output().skip_binder(); + // We defer the transmute to the end of typeck, once all inference vars have + // been resolved or we errored. This is important as we can only check transmute + // on concrete types, but the output type may not be known yet (it would only + // be known if explicitly specified via turbofish). + self.deferred_transmute_checks.borrow_mut().push((from, to, expr.span)); + } + if !tcx.features().unsized_fn_params { + // We want to remove some Sized bounds from std functions, + // but don't want to expose the removal to stable Rust. + // i.e., we don't want to allow + // + // ```rust + // drop as fn(str); + // ``` + // + // to work in stable even if the Sized bound on `drop` is relaxed. + for i in 0..fn_sig.inputs().skip_binder().len() { + // We just want to check sizedness, so instead of introducing + // placeholder lifetimes with probing, we just replace higher lifetimes + // with fresh vars. + let span = args.get(i).map(|a| a.span).unwrap_or(expr.span); + let input = self.replace_bound_vars_with_fresh_vars( + span, + infer::LateBoundRegionConversionTime::FnCall, + fn_sig.input(i), + ); + self.require_type_is_sized_deferred( + input, + span, + traits::SizedArgumentType(None), + ); + } + } + // Here we want to prevent struct constructors from returning unsized types. + // There were two cases this happened: fn pointer coercion in stable + // and usual function call in presence of unsized_locals. + // Also, as we just want to check sizedness, instead of introducing + // placeholder lifetimes with probing, we just replace higher lifetimes + // with fresh vars. + let output = self.replace_bound_vars_with_fresh_vars( + expr.span, + infer::LateBoundRegionConversionTime::FnCall, + fn_sig.output(), + ); + self.require_type_is_sized_deferred(output, expr.span, traits::SizedReturnType); + } + + // We always require that the type provided as the value for + // a type parameter outlives the moment of instantiation. + let substs = self.typeck_results.borrow().node_substs(expr.hir_id); + self.add_wf_bounds(substs, expr); + + ty + } + + fn check_expr_break( + &self, + destination: hir::Destination, + expr_opt: Option<&'tcx hir::Expr<'tcx>>, + expr: &'tcx hir::Expr<'tcx>, + ) -> Ty<'tcx> { + let tcx = self.tcx; + if let Ok(target_id) = destination.target_id { + let (e_ty, cause); + if let Some(e) = expr_opt { + // If this is a break with a value, we need to type-check + // the expression. Get an expected type from the loop context. + let opt_coerce_to = { + // We should release `enclosing_breakables` before the `check_expr_with_hint` + // below, so can't move this block of code to the enclosing scope and share + // `ctxt` with the second `enclosing_breakables` borrow below. + let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); + match enclosing_breakables.opt_find_breakable(target_id) { + Some(ctxt) => ctxt.coerce.as_ref().map(|coerce| coerce.expected_ty()), + None => { + // Avoid ICE when `break` is inside a closure (#65383). + return tcx.ty_error_with_message( + expr.span, + "break was outside loop, but no error was emitted", + ); + } + } + }; + + // If the loop context is not a `loop { }`, then break with + // a value is illegal, and `opt_coerce_to` will be `None`. + // Just set expectation to error in that case. + let coerce_to = opt_coerce_to.unwrap_or_else(|| tcx.ty_error()); + + // Recurse without `enclosing_breakables` borrowed. + e_ty = self.check_expr_with_hint(e, coerce_to); + cause = self.misc(e.span); + } else { + // Otherwise, this is a break *without* a value. That's + // always legal, and is equivalent to `break ()`. + e_ty = tcx.mk_unit(); + cause = self.misc(expr.span); + } + + // Now that we have type-checked `expr_opt`, borrow + // the `enclosing_loops` field and let's coerce the + // type of `expr_opt` into what is expected. + let mut enclosing_breakables = self.enclosing_breakables.borrow_mut(); + let Some(ctxt) = enclosing_breakables.opt_find_breakable(target_id) else { + // Avoid ICE when `break` is inside a closure (#65383). + return tcx.ty_error_with_message( + expr.span, + "break was outside loop, but no error was emitted", + ); + }; + + if let Some(ref mut coerce) = ctxt.coerce { + if let Some(ref e) = expr_opt { + coerce.coerce(self, &cause, e, e_ty); + } else { + assert!(e_ty.is_unit()); + let ty = coerce.expected_ty(); + coerce.coerce_forced_unit( + self, + &cause, + &mut |mut err| { + self.suggest_mismatched_types_on_tail( + &mut err, expr, ty, e_ty, target_id, + ); + if let Some(val) = ty_kind_suggestion(ty) { + let label = destination + .label + .map(|l| format!(" {}", l.ident)) + .unwrap_or_else(String::new); + err.span_suggestion( + expr.span, + "give it a value of the expected type", + format!("break{label} {val}"), + Applicability::HasPlaceholders, + ); + } + }, + false, + ); + } + } else { + // If `ctxt.coerce` is `None`, we can just ignore + // the type of the expression. This is because + // either this was a break *without* a value, in + // which case it is always a legal type (`()`), or + // else an error would have been flagged by the + // `loops` pass for using break with an expression + // where you are not supposed to. + assert!(expr_opt.is_none() || self.tcx.sess.has_errors().is_some()); + } + + // If we encountered a `break`, then (no surprise) it may be possible to break from the + // loop... unless the value being returned from the loop diverges itself, e.g. + // `break return 5` or `break loop {}`. + ctxt.may_break |= !self.diverges.get().is_always(); + + // the type of a `break` is always `!`, since it diverges + tcx.types.never + } else { + // Otherwise, we failed to find the enclosing loop; + // this can only happen if the `break` was not + // inside a loop at all, which is caught by the + // loop-checking pass. + let err = self.tcx.ty_error_with_message( + expr.span, + "break was outside loop, but no error was emitted", + ); + + // We still need to assign a type to the inner expression to + // prevent the ICE in #43162. + if let Some(e) = expr_opt { + self.check_expr_with_hint(e, err); + + // ... except when we try to 'break rust;'. + // ICE this expression in particular (see #43162). + if let ExprKind::Path(QPath::Resolved(_, path)) = e.kind { + if path.segments.len() == 1 && path.segments[0].ident.name == sym::rust { + fatally_break_rust(self.tcx.sess); + } + } + } + + // There was an error; make type-check fail. + err + } + } + + fn check_expr_return( + &self, + expr_opt: Option<&'tcx hir::Expr<'tcx>>, + expr: &'tcx hir::Expr<'tcx>, + ) -> Ty<'tcx> { + if self.ret_coercion.is_none() { + let mut err = ReturnStmtOutsideOfFnBody { + span: expr.span, + encl_body_span: None, + encl_fn_span: None, + }; + + let encl_item_id = self.tcx.hir().get_parent_item(expr.hir_id); + + if let Some(hir::Node::Item(hir::Item { + kind: hir::ItemKind::Fn(..), + span: encl_fn_span, + .. + })) + | Some(hir::Node::TraitItem(hir::TraitItem { + kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(_)), + span: encl_fn_span, + .. + })) + | Some(hir::Node::ImplItem(hir::ImplItem { + kind: hir::ImplItemKind::Fn(..), + span: encl_fn_span, + .. + })) = self.tcx.hir().find_by_def_id(encl_item_id) + { + // We are inside a function body, so reporting "return statement + // outside of function body" needs an explanation. + + let encl_body_owner_id = self.tcx.hir().enclosing_body_owner(expr.hir_id); + + // If this didn't hold, we would not have to report an error in + // the first place. + assert_ne!(encl_item_id, encl_body_owner_id); + + let encl_body_id = self.tcx.hir().body_owned_by(encl_body_owner_id); + let encl_body = self.tcx.hir().body(encl_body_id); + + err.encl_body_span = Some(encl_body.value.span); + err.encl_fn_span = Some(*encl_fn_span); + } + + self.tcx.sess.emit_err(err); + + if let Some(e) = expr_opt { + // We still have to type-check `e` (issue #86188), but calling + // `check_return_expr` only works inside fn bodies. + self.check_expr(e); + } + } else if let Some(e) = expr_opt { + if self.ret_coercion_span.get().is_none() { + self.ret_coercion_span.set(Some(e.span)); + } + self.check_return_expr(e, true); + } else { + let mut coercion = self.ret_coercion.as_ref().unwrap().borrow_mut(); + if self.ret_coercion_span.get().is_none() { + self.ret_coercion_span.set(Some(expr.span)); + } + let cause = self.cause(expr.span, ObligationCauseCode::ReturnNoExpression); + if let Some((fn_decl, _)) = self.get_fn_decl(expr.hir_id) { + coercion.coerce_forced_unit( + self, + &cause, + &mut |db| { + let span = fn_decl.output.span(); + if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) { + db.span_label( + span, + format!("expected `{snippet}` because of this return type"), + ); + } + }, + true, + ); + } else { + coercion.coerce_forced_unit(self, &cause, &mut |_| (), true); + } + } + self.tcx.types.never + } + + /// `explicit_return` is `true` if we're checking an explicit `return expr`, + /// and `false` if we're checking a trailing expression. + pub(super) fn check_return_expr( + &self, + return_expr: &'tcx hir::Expr<'tcx>, + explicit_return: bool, + ) { + let ret_coercion = self.ret_coercion.as_ref().unwrap_or_else(|| { + span_bug!(return_expr.span, "check_return_expr called outside fn body") + }); + + let ret_ty = ret_coercion.borrow().expected_ty(); + let return_expr_ty = self.check_expr_with_hint(return_expr, ret_ty); + let mut span = return_expr.span; + // Use the span of the trailing expression for our cause, + // not the span of the entire function + if !explicit_return { + if let ExprKind::Block(body, _) = return_expr.kind && let Some(last_expr) = body.expr { + span = last_expr.span; + } + } + ret_coercion.borrow_mut().coerce( + self, + &self.cause(span, ObligationCauseCode::ReturnValue(return_expr.hir_id)), + return_expr, + return_expr_ty, + ); + + if self.return_type_has_opaque { + // Point any obligations that were registered due to opaque type + // inference at the return expression. + self.select_obligations_where_possible(false, |errors| { + self.point_at_return_for_opaque_ty_error(errors, span, return_expr_ty); + }); + } + } + + fn point_at_return_for_opaque_ty_error( + &self, + errors: &mut Vec<traits::FulfillmentError<'tcx>>, + span: Span, + return_expr_ty: Ty<'tcx>, + ) { + // Don't point at the whole block if it's empty + if span == self.tcx.hir().span(self.body_id) { + return; + } + for err in errors { + let cause = &mut err.obligation.cause; + if let ObligationCauseCode::OpaqueReturnType(None) = cause.code() { + let new_cause = ObligationCause::new( + cause.span, + cause.body_id, + ObligationCauseCode::OpaqueReturnType(Some((return_expr_ty, span))), + ); + *cause = new_cause; + } + } + } + + pub(crate) fn check_lhs_assignable( + &self, + lhs: &'tcx hir::Expr<'tcx>, + err_code: &'static str, + op_span: Span, + adjust_err: impl FnOnce(&mut DiagnosticBuilder<'tcx, ErrorGuaranteed>), + ) { + if lhs.is_syntactic_place_expr() { + return; + } + + // FIXME: Make this use SessionDiagnostic once error codes can be dynamically set. + let mut err = self.tcx.sess.struct_span_err_with_code( + op_span, + "invalid left-hand side of assignment", + DiagnosticId::Error(err_code.into()), + ); + err.span_label(lhs.span, "cannot assign to this expression"); + + self.comes_from_while_condition(lhs.hir_id, |expr| { + err.span_suggestion_verbose( + expr.span.shrink_to_lo(), + "you might have meant to use pattern destructuring", + "let ", + Applicability::MachineApplicable, + ); + }); + + adjust_err(&mut err); + + err.emit(); + } + + // Check if an expression `original_expr_id` comes from the condition of a while loop, + // as opposed from the body of a while loop, which we can naively check by iterating + // parents until we find a loop... + pub(super) fn comes_from_while_condition( + &self, + original_expr_id: HirId, + then: impl FnOnce(&hir::Expr<'_>), + ) { + let mut parent = self.tcx.hir().get_parent_node(original_expr_id); + while let Some(node) = self.tcx.hir().find(parent) { + match node { + hir::Node::Expr(hir::Expr { + kind: + hir::ExprKind::Loop( + hir::Block { + expr: + Some(hir::Expr { + kind: + hir::ExprKind::Match(expr, ..) | hir::ExprKind::If(expr, ..), + .. + }), + .. + }, + _, + hir::LoopSource::While, + _, + ), + .. + }) => { + // Check if our original expression is a child of the condition of a while loop + let expr_is_ancestor = std::iter::successors(Some(original_expr_id), |id| { + self.tcx.hir().find_parent_node(*id) + }) + .take_while(|id| *id != parent) + .any(|id| id == expr.hir_id); + // if it is, then we have a situation like `while Some(0) = value.get(0) {`, + // where `while let` was more likely intended. + if expr_is_ancestor { + then(expr); + } + break; + } + hir::Node::Item(_) + | hir::Node::ImplItem(_) + | hir::Node::TraitItem(_) + | hir::Node::Crate(_) => break, + _ => { + parent = self.tcx.hir().get_parent_node(parent); + } + } + } + } + + // A generic function for checking the 'then' and 'else' clauses in an 'if' + // or 'if-else' expression. + fn check_then_else( + &self, + cond_expr: &'tcx hir::Expr<'tcx>, + then_expr: &'tcx hir::Expr<'tcx>, + opt_else_expr: Option<&'tcx hir::Expr<'tcx>>, + sp: Span, + orig_expected: Expectation<'tcx>, + ) -> Ty<'tcx> { + let cond_ty = self.check_expr_has_type_or_error(cond_expr, self.tcx.types.bool, |_| {}); + + self.warn_if_unreachable( + cond_expr.hir_id, + then_expr.span, + "block in `if` or `while` expression", + ); + + let cond_diverges = self.diverges.get(); + self.diverges.set(Diverges::Maybe); + + let expected = orig_expected.adjust_for_branches(self); + let then_ty = self.check_expr_with_expectation(then_expr, expected); + let then_diverges = self.diverges.get(); + self.diverges.set(Diverges::Maybe); + + // We've already taken the expected type's preferences + // into account when typing the `then` branch. To figure + // out the initial shot at a LUB, we thus only consider + // `expected` if it represents a *hard* constraint + // (`only_has_type`); otherwise, we just go with a + // fresh type variable. + let coerce_to_ty = expected.coercion_target_type(self, sp); + let mut coerce: DynamicCoerceMany<'_> = CoerceMany::new(coerce_to_ty); + + coerce.coerce(self, &self.misc(sp), then_expr, then_ty); + + if let Some(else_expr) = opt_else_expr { + let else_ty = self.check_expr_with_expectation(else_expr, expected); + let else_diverges = self.diverges.get(); + + let opt_suggest_box_span = self.opt_suggest_box_span(else_ty, orig_expected); + let if_cause = self.if_cause( + sp, + cond_expr.span, + then_expr, + else_expr, + then_ty, + else_ty, + opt_suggest_box_span, + ); + + coerce.coerce(self, &if_cause, else_expr, else_ty); + + // We won't diverge unless both branches do (or the condition does). + self.diverges.set(cond_diverges | then_diverges & else_diverges); + } else { + self.if_fallback_coercion(sp, then_expr, &mut coerce); + + // If the condition is false we can't diverge. + self.diverges.set(cond_diverges); + } + + let result_ty = coerce.complete(self); + if cond_ty.references_error() { self.tcx.ty_error() } else { result_ty } + } + + /// Type check assignment expression `expr` of form `lhs = rhs`. + /// The expected type is `()` and is passed to the function for the purposes of diagnostics. + fn check_expr_assign( + &self, + expr: &'tcx hir::Expr<'tcx>, + expected: Expectation<'tcx>, + lhs: &'tcx hir::Expr<'tcx>, + rhs: &'tcx hir::Expr<'tcx>, + span: Span, + ) -> Ty<'tcx> { + let expected_ty = expected.coercion_target_type(self, expr.span); + if expected_ty == self.tcx.types.bool { + // The expected type is `bool` but this will result in `()` so we can reasonably + // say that the user intended to write `lhs == rhs` instead of `lhs = rhs`. + // The likely cause of this is `if foo = bar { .. }`. + let actual_ty = self.tcx.mk_unit(); + let mut err = self.demand_suptype_diag(expr.span, expected_ty, actual_ty).unwrap(); + let lhs_ty = self.check_expr(&lhs); + let rhs_ty = self.check_expr(&rhs); + let (applicability, eq) = if self.can_coerce(rhs_ty, lhs_ty) { + (Applicability::MachineApplicable, true) + } else { + (Applicability::MaybeIncorrect, false) + }; + if !lhs.is_syntactic_place_expr() + && lhs.is_approximately_pattern() + && !matches!(lhs.kind, hir::ExprKind::Lit(_)) + { + // Do not suggest `if let x = y` as `==` is way more likely to be the intention. + let hir = self.tcx.hir(); + if let hir::Node::Expr(hir::Expr { kind: ExprKind::If { .. }, .. }) = + hir.get(hir.get_parent_node(hir.get_parent_node(expr.hir_id))) + { + err.span_suggestion_verbose( + expr.span.shrink_to_lo(), + "you might have meant to use pattern matching", + "let ", + applicability, + ); + }; + } + if eq { + err.span_suggestion_verbose( + span, + "you might have meant to compare for equality", + "==", + applicability, + ); + } + + // If the assignment expression itself is ill-formed, don't + // bother emitting another error + if lhs_ty.references_error() || rhs_ty.references_error() { + err.delay_as_bug() + } else { + err.emit(); + } + return self.tcx.ty_error(); + } + + let lhs_ty = self.check_expr_with_needs(&lhs, Needs::MutPlace); + + let suggest_deref_binop = |err: &mut DiagnosticBuilder<'tcx, ErrorGuaranteed>, + rhs_ty: Ty<'tcx>| { + if let Some(lhs_deref_ty) = self.deref_once_mutably_for_diagnostic(lhs_ty) { + // Can only assign if the type is sized, so if `DerefMut` yields a type that is + // unsized, do not suggest dereferencing it. + let lhs_deref_ty_is_sized = self + .infcx + .type_implements_trait( + self.tcx.lang_items().sized_trait().unwrap(), + lhs_deref_ty, + ty::List::empty(), + self.param_env, + ) + .may_apply(); + if lhs_deref_ty_is_sized && self.can_coerce(rhs_ty, lhs_deref_ty) { + err.span_suggestion_verbose( + lhs.span.shrink_to_lo(), + "consider dereferencing here to assign to the mutably borrowed value", + "*", + Applicability::MachineApplicable, + ); + } + } + }; + + self.check_lhs_assignable(lhs, "E0070", span, |err| { + let rhs_ty = self.check_expr(&rhs); + suggest_deref_binop(err, rhs_ty); + }); + + // This is (basically) inlined `check_expr_coercable_to_type`, but we want + // to suggest an additional fixup here in `suggest_deref_binop`. + let rhs_ty = self.check_expr_with_hint(&rhs, lhs_ty); + if let (_, Some(mut diag)) = + self.demand_coerce_diag(rhs, rhs_ty, lhs_ty, Some(lhs), AllowTwoPhase::No) + { + suggest_deref_binop(&mut diag, rhs_ty); + diag.emit(); + } + + self.require_type_is_sized(lhs_ty, lhs.span, traits::AssignmentLhsSized); + + if lhs_ty.references_error() || rhs_ty.references_error() { + self.tcx.ty_error() + } else { + self.tcx.mk_unit() + } + } + + pub(super) fn check_expr_let(&self, let_expr: &'tcx hir::Let<'tcx>) -> Ty<'tcx> { + // for let statements, this is done in check_stmt + let init = let_expr.init; + self.warn_if_unreachable(init.hir_id, init.span, "block in `let` expression"); + // otherwise check exactly as a let statement + self.check_decl(let_expr.into()); + // but return a bool, for this is a boolean expression + self.tcx.types.bool + } + + fn check_expr_loop( + &self, + body: &'tcx hir::Block<'tcx>, + source: hir::LoopSource, + expected: Expectation<'tcx>, + expr: &'tcx hir::Expr<'tcx>, + ) -> Ty<'tcx> { + let coerce = match source { + // you can only use break with a value from a normal `loop { }` + hir::LoopSource::Loop => { + let coerce_to = expected.coercion_target_type(self, body.span); + Some(CoerceMany::new(coerce_to)) + } + + hir::LoopSource::While | hir::LoopSource::ForLoop => None, + }; + + let ctxt = BreakableCtxt { + coerce, + may_break: false, // Will get updated if/when we find a `break`. + }; + + let (ctxt, ()) = self.with_breakable_ctxt(expr.hir_id, ctxt, || { + self.check_block_no_value(&body); + }); + + if ctxt.may_break { + // No way to know whether it's diverging because + // of a `break` or an outer `break` or `return`. + self.diverges.set(Diverges::Maybe); + } + + // If we permit break with a value, then result type is + // the LUB of the breaks (possibly ! if none); else, it + // is nil. This makes sense because infinite loops + // (which would have type !) are only possible iff we + // permit break with a value [1]. + if ctxt.coerce.is_none() && !ctxt.may_break { + // [1] + self.tcx.sess.delay_span_bug(body.span, "no coercion, but loop may not break"); + } + ctxt.coerce.map(|c| c.complete(self)).unwrap_or_else(|| self.tcx.mk_unit()) + } + + /// Checks a method call. + fn check_method_call( + &self, + expr: &'tcx hir::Expr<'tcx>, + segment: &hir::PathSegment<'_>, + args: &'tcx [hir::Expr<'tcx>], + expected: Expectation<'tcx>, + ) -> Ty<'tcx> { + let rcvr = &args[0]; + let rcvr_t = self.check_expr(&rcvr); + // no need to check for bot/err -- callee does that + let rcvr_t = self.structurally_resolved_type(args[0].span, rcvr_t); + let span = segment.ident.span; + + let method = match self.lookup_method(rcvr_t, segment, span, expr, rcvr, args) { + Ok(method) => { + // We could add a "consider `foo::<params>`" suggestion here, but I wasn't able to + // trigger this codepath causing `structurally_resolved_type` to emit an error. + + self.write_method_call(expr.hir_id, method); + Ok(method) + } + Err(error) => { + if segment.ident.name != kw::Empty { + if let Some(mut err) = self.report_method_error( + span, + rcvr_t, + segment.ident, + SelfSource::MethodCall(&args[0]), + error, + Some(args), + ) { + err.emit(); + } + } + Err(()) + } + }; + + // Call the generic checker. + self.check_method_argument_types( + span, + expr, + method, + &args[1..], + DontTupleArguments, + expected, + ) + } + + fn check_expr_cast( + &self, + e: &'tcx hir::Expr<'tcx>, + t: &'tcx hir::Ty<'tcx>, + expr: &'tcx hir::Expr<'tcx>, + ) -> Ty<'tcx> { + // Find the type of `e`. Supply hints based on the type we are casting to, + // if appropriate. + let t_cast = self.to_ty_saving_user_provided_ty(t); + let t_cast = self.resolve_vars_if_possible(t_cast); + let t_expr = self.check_expr_with_expectation(e, ExpectCastableToType(t_cast)); + let t_expr = self.resolve_vars_if_possible(t_expr); + + // Eagerly check for some obvious errors. + if t_expr.references_error() || t_cast.references_error() { + self.tcx.ty_error() + } else { + // Defer other checks until we're done type checking. + let mut deferred_cast_checks = self.deferred_cast_checks.borrow_mut(); + match cast::CastCheck::new(self, e, t_expr, t_cast, t.span, expr.span) { + Ok(cast_check) => { + debug!( + "check_expr_cast: deferring cast from {:?} to {:?}: {:?}", + t_cast, t_expr, cast_check, + ); + deferred_cast_checks.push(cast_check); + t_cast + } + Err(_) => self.tcx.ty_error(), + } + } + } + + fn check_expr_array( + &self, + args: &'tcx [hir::Expr<'tcx>], + expected: Expectation<'tcx>, + expr: &'tcx hir::Expr<'tcx>, + ) -> Ty<'tcx> { + let element_ty = if !args.is_empty() { + let coerce_to = expected + .to_option(self) + .and_then(|uty| match *uty.kind() { + ty::Array(ty, _) | ty::Slice(ty) => Some(ty), + _ => None, + }) + .unwrap_or_else(|| { + self.next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::TypeInference, + span: expr.span, + }) + }); + let mut coerce = CoerceMany::with_coercion_sites(coerce_to, args); + assert_eq!(self.diverges.get(), Diverges::Maybe); + for e in args { + let e_ty = self.check_expr_with_hint(e, coerce_to); + let cause = self.misc(e.span); + coerce.coerce(self, &cause, e, e_ty); + } + coerce.complete(self) + } else { + self.next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::TypeInference, + span: expr.span, + }) + }; + self.tcx.mk_array(element_ty, args.len() as u64) + } + + fn check_expr_const_block( + &self, + anon_const: &'tcx hir::AnonConst, + expected: Expectation<'tcx>, + _expr: &'tcx hir::Expr<'tcx>, + ) -> Ty<'tcx> { + let body = self.tcx.hir().body(anon_const.body); + + // Create a new function context. + let fcx = FnCtxt::new(self, self.param_env.with_const(), body.value.hir_id); + crate::check::GatherLocalsVisitor::new(&fcx).visit_body(body); + + let ty = fcx.check_expr_with_expectation(&body.value, expected); + fcx.require_type_is_sized(ty, body.value.span, traits::ConstSized); + fcx.write_ty(anon_const.hir_id, ty); + ty + } + + fn check_expr_repeat( + &self, + element: &'tcx hir::Expr<'tcx>, + count: &'tcx hir::ArrayLen, + expected: Expectation<'tcx>, + _expr: &'tcx hir::Expr<'tcx>, + ) -> Ty<'tcx> { + let tcx = self.tcx; + let count = self.array_length_to_const(count); + + let uty = match expected { + ExpectHasType(uty) => match *uty.kind() { + ty::Array(ty, _) | ty::Slice(ty) => Some(ty), + _ => None, + }, + _ => None, + }; + + let (element_ty, t) = match uty { + Some(uty) => { + self.check_expr_coercable_to_type(&element, uty, None); + (uty, uty) + } + None => { + let ty = self.next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::MiscVariable, + span: element.span, + }); + let element_ty = self.check_expr_has_type_or_error(&element, ty, |_| {}); + (element_ty, ty) + } + }; + + if element_ty.references_error() { + return tcx.ty_error(); + } + + self.check_repeat_element_needs_copy_bound(element, count, element_ty); + + tcx.mk_ty(ty::Array(t, count)) + } + + fn check_repeat_element_needs_copy_bound( + &self, + element: &hir::Expr<'_>, + count: ty::Const<'tcx>, + element_ty: Ty<'tcx>, + ) { + let tcx = self.tcx; + // Actual constants as the repeat element get inserted repeatedly instead of getting copied via Copy. + match &element.kind { + hir::ExprKind::ConstBlock(..) => return, + hir::ExprKind::Path(qpath) => { + let res = self.typeck_results.borrow().qpath_res(qpath, element.hir_id); + if let Res::Def(DefKind::Const | DefKind::AssocConst | DefKind::AnonConst, _) = res + { + return; + } + } + _ => {} + } + // If someone calls a const fn, they can extract that call out into a separate constant (or a const + // block in the future), so we check that to tell them that in the diagnostic. Does not affect typeck. + let is_const_fn = match element.kind { + hir::ExprKind::Call(func, _args) => match *self.node_ty(func.hir_id).kind() { + ty::FnDef(def_id, _) => tcx.is_const_fn(def_id), + _ => false, + }, + _ => false, + }; + + // If the length is 0, we don't create any elements, so we don't copy any. If the length is 1, we + // don't copy that one element, we move it. Only check for Copy if the length is larger. + if count.try_eval_usize(tcx, self.param_env).map_or(true, |len| len > 1) { + let lang_item = self.tcx.require_lang_item(LangItem::Copy, None); + let code = traits::ObligationCauseCode::RepeatElementCopy { is_const_fn }; + self.require_type_meets(element_ty, element.span, code, lang_item); + } + } + + fn check_expr_tuple( + &self, + elts: &'tcx [hir::Expr<'tcx>], + expected: Expectation<'tcx>, + expr: &'tcx hir::Expr<'tcx>, + ) -> Ty<'tcx> { + let flds = expected.only_has_type(self).and_then(|ty| { + let ty = self.resolve_vars_with_obligations(ty); + match ty.kind() { + ty::Tuple(flds) => Some(&flds[..]), + _ => None, + } + }); + + let elt_ts_iter = elts.iter().enumerate().map(|(i, e)| match flds { + Some(fs) if i < fs.len() => { + let ety = fs[i]; + self.check_expr_coercable_to_type(&e, ety, None); + ety + } + _ => self.check_expr_with_expectation(&e, NoExpectation), + }); + let tuple = self.tcx.mk_tup(elt_ts_iter); + if tuple.references_error() { + self.tcx.ty_error() + } else { + self.require_type_is_sized(tuple, expr.span, traits::TupleInitializerSized); + tuple + } + } + + fn check_expr_struct( + &self, + expr: &hir::Expr<'_>, + expected: Expectation<'tcx>, + qpath: &QPath<'_>, + fields: &'tcx [hir::ExprField<'tcx>], + base_expr: &'tcx Option<&'tcx hir::Expr<'tcx>>, + ) -> Ty<'tcx> { + // Find the relevant variant + let Some((variant, adt_ty)) = self.check_struct_path(qpath, expr.hir_id) else { + self.check_struct_fields_on_error(fields, base_expr); + return self.tcx.ty_error(); + }; + + // Prohibit struct expressions when non-exhaustive flag is set. + let adt = adt_ty.ty_adt_def().expect("`check_struct_path` returned non-ADT type"); + if !adt.did().is_local() && variant.is_field_list_non_exhaustive() { + self.tcx + .sess + .emit_err(StructExprNonExhaustive { span: expr.span, what: adt.variant_descr() }); + } + + self.check_expr_struct_fields( + adt_ty, + expected, + expr.hir_id, + qpath.span(), + variant, + fields, + base_expr, + expr.span, + ); + + self.require_type_is_sized(adt_ty, expr.span, traits::StructInitializerSized); + adt_ty + } + + fn check_expr_struct_fields( + &self, + adt_ty: Ty<'tcx>, + expected: Expectation<'tcx>, + expr_id: hir::HirId, + span: Span, + variant: &'tcx ty::VariantDef, + ast_fields: &'tcx [hir::ExprField<'tcx>], + base_expr: &'tcx Option<&'tcx hir::Expr<'tcx>>, + expr_span: Span, + ) { + let tcx = self.tcx; + + let expected_inputs = + self.expected_inputs_for_expected_output(span, expected, adt_ty, &[adt_ty]); + let adt_ty_hint = if let Some(expected_inputs) = expected_inputs { + expected_inputs.get(0).cloned().unwrap_or(adt_ty) + } else { + adt_ty + }; + // re-link the regions that EIfEO can erase. + self.demand_eqtype(span, adt_ty_hint, adt_ty); + + let ty::Adt(adt, substs) = adt_ty.kind() else { + span_bug!(span, "non-ADT passed to check_expr_struct_fields"); + }; + let adt_kind = adt.adt_kind(); + + let mut remaining_fields = variant + .fields + .iter() + .enumerate() + .map(|(i, field)| (field.ident(tcx).normalize_to_macros_2_0(), (i, field))) + .collect::<FxHashMap<_, _>>(); + + let mut seen_fields = FxHashMap::default(); + + let mut error_happened = false; + + // Type-check each field. + for field in ast_fields { + let ident = tcx.adjust_ident(field.ident, variant.def_id); + let field_type = if let Some((i, v_field)) = remaining_fields.remove(&ident) { + seen_fields.insert(ident, field.span); + self.write_field_index(field.hir_id, i); + + // We don't look at stability attributes on + // struct-like enums (yet...), but it's definitely not + // a bug to have constructed one. + if adt_kind != AdtKind::Enum { + tcx.check_stability(v_field.did, Some(expr_id), field.span, None); + } + + self.field_ty(field.span, v_field, substs) + } else { + error_happened = true; + if let Some(prev_span) = seen_fields.get(&ident) { + tcx.sess.emit_err(FieldMultiplySpecifiedInInitializer { + span: field.ident.span, + prev_span: *prev_span, + ident, + }); + } else { + self.report_unknown_field( + adt_ty, + variant, + field, + ast_fields, + adt.variant_descr(), + expr_span, + ); + } + + tcx.ty_error() + }; + + // Make sure to give a type to the field even if there's + // an error, so we can continue type-checking. + self.check_expr_coercable_to_type(&field.expr, field_type, None); + } + + // Make sure the programmer specified correct number of fields. + if adt_kind == AdtKind::Union { + if ast_fields.len() != 1 { + struct_span_err!( + tcx.sess, + span, + E0784, + "union expressions should have exactly one field", + ) + .emit(); + } + } + + // If check_expr_struct_fields hit an error, do not attempt to populate + // the fields with the base_expr. This could cause us to hit errors later + // when certain fields are assumed to exist that in fact do not. + if error_happened { + return; + } + + if let Some(base_expr) = base_expr { + // FIXME: We are currently creating two branches here in order to maintain + // consistency. But they should be merged as much as possible. + let fru_tys = if self.tcx.features().type_changing_struct_update { + if adt.is_struct() { + // Make some fresh substitutions for our ADT type. + let fresh_substs = self.fresh_substs_for_item(base_expr.span, adt.did()); + // We do subtyping on the FRU fields first, so we can + // learn exactly what types we expect the base expr + // needs constrained to be compatible with the struct + // type we expect from the expectation value. + let fru_tys = variant + .fields + .iter() + .map(|f| { + let fru_ty = self.normalize_associated_types_in( + expr_span, + self.field_ty(base_expr.span, f, fresh_substs), + ); + let ident = self.tcx.adjust_ident(f.ident(self.tcx), variant.def_id); + if let Some(_) = remaining_fields.remove(&ident) { + let target_ty = self.field_ty(base_expr.span, f, substs); + let cause = self.misc(base_expr.span); + match self.at(&cause, self.param_env).sup(target_ty, fru_ty) { + Ok(InferOk { obligations, value: () }) => { + self.register_predicates(obligations) + } + Err(_) => { + // This should never happen, since we're just subtyping the + // remaining_fields, but it's fine to emit this, I guess. + self.report_mismatched_types( + &cause, + target_ty, + fru_ty, + FieldMisMatch(variant.name, ident.name), + ) + .emit(); + } + } + } + self.resolve_vars_if_possible(fru_ty) + }) + .collect(); + // The use of fresh substs that we have subtyped against + // our base ADT type's fields allows us to guide inference + // along so that, e.g. + // ``` + // MyStruct<'a, F1, F2, const C: usize> { + // f: F1, + // // Other fields that reference `'a`, `F2`, and `C` + // } + // + // let x = MyStruct { + // f: 1usize, + // ..other_struct + // }; + // ``` + // will have the `other_struct` expression constrained to + // `MyStruct<'a, _, F2, C>`, as opposed to just `_`... + // This is important to allow coercions to happen in + // `other_struct` itself. See `coerce-in-base-expr.rs`. + let fresh_base_ty = self.tcx.mk_adt(*adt, fresh_substs); + self.check_expr_has_type_or_error( + base_expr, + self.resolve_vars_if_possible(fresh_base_ty), + |_| {}, + ); + fru_tys + } else { + // Check the base_expr, regardless of a bad expected adt_ty, so we can get + // type errors on that expression, too. + self.check_expr(base_expr); + self.tcx + .sess + .emit_err(FunctionalRecordUpdateOnNonStruct { span: base_expr.span }); + return; + } + } else { + self.check_expr_has_type_or_error(base_expr, adt_ty, |_| { + let base_ty = self.typeck_results.borrow().expr_ty(*base_expr); + let same_adt = match (adt_ty.kind(), base_ty.kind()) { + (ty::Adt(adt, _), ty::Adt(base_adt, _)) if adt == base_adt => true, + _ => false, + }; + if self.tcx.sess.is_nightly_build() && same_adt { + feature_err( + &self.tcx.sess.parse_sess, + sym::type_changing_struct_update, + base_expr.span, + "type changing struct updating is experimental", + ) + .emit(); + } + }); + match adt_ty.kind() { + ty::Adt(adt, substs) if adt.is_struct() => variant + .fields + .iter() + .map(|f| { + self.normalize_associated_types_in(expr_span, f.ty(self.tcx, substs)) + }) + .collect(), + _ => { + self.tcx + .sess + .emit_err(FunctionalRecordUpdateOnNonStruct { span: base_expr.span }); + return; + } + } + }; + self.typeck_results.borrow_mut().fru_field_types_mut().insert(expr_id, fru_tys); + } else if adt_kind != AdtKind::Union && !remaining_fields.is_empty() { + debug!(?remaining_fields); + let private_fields: Vec<&ty::FieldDef> = variant + .fields + .iter() + .filter(|field| { + !field.vis.is_accessible_from(tcx.parent_module(expr_id).to_def_id(), tcx) + }) + .collect(); + + if !private_fields.is_empty() { + self.report_private_fields(adt_ty, span, private_fields, ast_fields); + } else { + self.report_missing_fields( + adt_ty, + span, + remaining_fields, + variant, + ast_fields, + substs, + ); + } + } + } + + fn check_struct_fields_on_error( + &self, + fields: &'tcx [hir::ExprField<'tcx>], + base_expr: &'tcx Option<&'tcx hir::Expr<'tcx>>, + ) { + for field in fields { + self.check_expr(&field.expr); + } + if let Some(base) = *base_expr { + self.check_expr(&base); + } + } + + /// Report an error for a struct field expression when there are fields which aren't provided. + /// + /// ```text + /// error: missing field `you_can_use_this_field` in initializer of `foo::Foo` + /// --> src/main.rs:8:5 + /// | + /// 8 | foo::Foo {}; + /// | ^^^^^^^^ missing `you_can_use_this_field` + /// + /// error: aborting due to previous error + /// ``` + fn report_missing_fields( + &self, + adt_ty: Ty<'tcx>, + span: Span, + remaining_fields: FxHashMap<Ident, (usize, &ty::FieldDef)>, + variant: &'tcx ty::VariantDef, + ast_fields: &'tcx [hir::ExprField<'tcx>], + substs: SubstsRef<'tcx>, + ) { + let len = remaining_fields.len(); + + let mut displayable_field_names: Vec<&str> = + remaining_fields.keys().map(|ident| ident.as_str()).collect(); + // sorting &str primitives here, sort_unstable is ok + displayable_field_names.sort_unstable(); + + let mut truncated_fields_error = String::new(); + let remaining_fields_names = match &displayable_field_names[..] { + [field1] => format!("`{}`", field1), + [field1, field2] => format!("`{field1}` and `{field2}`"), + [field1, field2, field3] => format!("`{field1}`, `{field2}` and `{field3}`"), + _ => { + truncated_fields_error = + format!(" and {} other field{}", len - 3, pluralize!(len - 3)); + displayable_field_names + .iter() + .take(3) + .map(|n| format!("`{n}`")) + .collect::<Vec<_>>() + .join(", ") + } + }; + + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0063, + "missing field{} {}{} in initializer of `{}`", + pluralize!(len), + remaining_fields_names, + truncated_fields_error, + adt_ty + ); + err.span_label(span, format!("missing {remaining_fields_names}{truncated_fields_error}")); + + // If the last field is a range literal, but it isn't supposed to be, then they probably + // meant to use functional update syntax. + // + // I don't use 'is_range_literal' because only double-sided, half-open ranges count. + if let Some(( + last, + ExprKind::Struct( + QPath::LangItem(LangItem::Range, ..), + &[ref range_start, ref range_end], + _, + ), + )) = ast_fields.last().map(|last| (last, &last.expr.kind)) && + let variant_field = + variant.fields.iter().find(|field| field.ident(self.tcx) == last.ident) && + let range_def_id = self.tcx.lang_items().range_struct() && + variant_field + .and_then(|field| field.ty(self.tcx, substs).ty_adt_def()) + .map(|adt| adt.did()) + != range_def_id + { + let instead = self + .tcx + .sess + .source_map() + .span_to_snippet(range_end.expr.span) + .map(|s| format!(" from `{s}`")) + .unwrap_or_default(); + err.span_suggestion( + range_start.span.shrink_to_hi(), + &format!("to set the remaining fields{instead}, separate the last named field with a comma"), + ",", + Applicability::MaybeIncorrect, + ); + } + + err.emit(); + } + + /// Report an error for a struct field expression when there are invisible fields. + /// + /// ```text + /// error: cannot construct `Foo` with struct literal syntax due to private fields + /// --> src/main.rs:8:5 + /// | + /// 8 | foo::Foo {}; + /// | ^^^^^^^^ + /// + /// error: aborting due to previous error + /// ``` + fn report_private_fields( + &self, + adt_ty: Ty<'tcx>, + span: Span, + private_fields: Vec<&ty::FieldDef>, + used_fields: &'tcx [hir::ExprField<'tcx>], + ) { + let mut err = self.tcx.sess.struct_span_err( + span, + &format!( + "cannot construct `{adt_ty}` with struct literal syntax due to private fields", + ), + ); + let (used_private_fields, remaining_private_fields): ( + Vec<(Symbol, Span, bool)>, + Vec<(Symbol, Span, bool)>, + ) = private_fields + .iter() + .map(|field| { + match used_fields.iter().find(|used_field| field.name == used_field.ident.name) { + Some(used_field) => (field.name, used_field.span, true), + None => (field.name, self.tcx.def_span(field.did), false), + } + }) + .partition(|field| field.2); + err.span_labels(used_private_fields.iter().map(|(_, span, _)| *span), "private field"); + if !remaining_private_fields.is_empty() { + let remaining_private_fields_len = remaining_private_fields.len(); + let names = match &remaining_private_fields + .iter() + .map(|(name, _, _)| name) + .collect::<Vec<_>>()[..] + { + _ if remaining_private_fields_len > 6 => String::new(), + [name] => format!("`{name}` "), + [names @ .., last] => { + let names = names.iter().map(|name| format!("`{name}`")).collect::<Vec<_>>(); + format!("{} and `{last}` ", names.join(", ")) + } + [] => unreachable!(), + }; + err.note(format!( + "... and other private field{s} {names}that {were} not provided", + s = pluralize!(remaining_private_fields_len), + were = pluralize!("was", remaining_private_fields_len), + )); + } + err.emit(); + } + + fn report_unknown_field( + &self, + ty: Ty<'tcx>, + variant: &'tcx ty::VariantDef, + field: &hir::ExprField<'_>, + skip_fields: &[hir::ExprField<'_>], + kind_name: &str, + expr_span: Span, + ) { + if variant.is_recovered() { + self.set_tainted_by_errors(); + return; + } + let mut err = self.type_error_struct_with_diag( + field.ident.span, + |actual| match ty.kind() { + ty::Adt(adt, ..) if adt.is_enum() => struct_span_err!( + self.tcx.sess, + field.ident.span, + E0559, + "{} `{}::{}` has no field named `{}`", + kind_name, + actual, + variant.name, + field.ident + ), + _ => struct_span_err!( + self.tcx.sess, + field.ident.span, + E0560, + "{} `{}` has no field named `{}`", + kind_name, + actual, + field.ident + ), + }, + ty, + ); + + let variant_ident_span = self.tcx.def_ident_span(variant.def_id).unwrap(); + match variant.ctor_kind { + CtorKind::Fn => match ty.kind() { + ty::Adt(adt, ..) if adt.is_enum() => { + err.span_label( + variant_ident_span, + format!( + "`{adt}::{variant}` defined here", + adt = ty, + variant = variant.name, + ), + ); + err.span_label(field.ident.span, "field does not exist"); + err.span_suggestion_verbose( + expr_span, + &format!( + "`{adt}::{variant}` is a tuple {kind_name}, use the appropriate syntax", + adt = ty, + variant = variant.name, + ), + format!( + "{adt}::{variant}(/* fields */)", + adt = ty, + variant = variant.name, + ), + Applicability::HasPlaceholders, + ); + } + _ => { + err.span_label(variant_ident_span, format!("`{adt}` defined here", adt = ty)); + err.span_label(field.ident.span, "field does not exist"); + err.span_suggestion_verbose( + expr_span, + &format!( + "`{adt}` is a tuple {kind_name}, use the appropriate syntax", + adt = ty, + kind_name = kind_name, + ), + format!("{adt}(/* fields */)", adt = ty), + Applicability::HasPlaceholders, + ); + } + }, + _ => { + // prevent all specified fields from being suggested + let skip_fields = skip_fields.iter().map(|x| x.ident.name); + if let Some(field_name) = self.suggest_field_name( + variant, + field.ident.name, + skip_fields.collect(), + expr_span, + ) { + err.span_suggestion( + field.ident.span, + "a field with a similar name exists", + field_name, + Applicability::MaybeIncorrect, + ); + } else { + match ty.kind() { + ty::Adt(adt, ..) => { + if adt.is_enum() { + err.span_label( + field.ident.span, + format!("`{}::{}` does not have this field", ty, variant.name), + ); + } else { + err.span_label( + field.ident.span, + format!("`{ty}` does not have this field"), + ); + } + let available_field_names = + self.available_field_names(variant, expr_span); + if !available_field_names.is_empty() { + err.note(&format!( + "available fields are: {}", + self.name_series_display(available_field_names) + )); + } + } + _ => bug!("non-ADT passed to report_unknown_field"), + } + }; + } + } + err.emit(); + } + + // Return a hint about the closest match in field names + fn suggest_field_name( + &self, + variant: &'tcx ty::VariantDef, + field: Symbol, + skip: Vec<Symbol>, + // The span where stability will be checked + span: Span, + ) -> Option<Symbol> { + let names = variant + .fields + .iter() + .filter_map(|field| { + // ignore already set fields and private fields from non-local crates + // and unstable fields. + if skip.iter().any(|&x| x == field.name) + || (!variant.def_id.is_local() && !field.vis.is_public()) + || matches!( + self.tcx.eval_stability(field.did, None, span, None), + stability::EvalResult::Deny { .. } + ) + { + None + } else { + Some(field.name) + } + }) + .collect::<Vec<Symbol>>(); + + find_best_match_for_name(&names, field, None) + } + + fn available_field_names( + &self, + variant: &'tcx ty::VariantDef, + access_span: Span, + ) -> Vec<Symbol> { + variant + .fields + .iter() + .filter(|field| { + let def_scope = self + .tcx + .adjust_ident_and_get_scope(field.ident(self.tcx), variant.def_id, self.body_id) + .1; + field.vis.is_accessible_from(def_scope, self.tcx) + && !matches!( + self.tcx.eval_stability(field.did, None, access_span, None), + stability::EvalResult::Deny { .. } + ) + }) + .filter(|field| !self.tcx.is_doc_hidden(field.did)) + .map(|field| field.name) + .collect() + } + + fn name_series_display(&self, names: Vec<Symbol>) -> String { + // dynamic limit, to never omit just one field + let limit = if names.len() == 6 { 6 } else { 5 }; + let mut display = + names.iter().take(limit).map(|n| format!("`{}`", n)).collect::<Vec<_>>().join(", "); + if names.len() > limit { + display = format!("{} ... and {} others", display, names.len() - limit); + } + display + } + + // Check field access expressions + fn check_field( + &self, + expr: &'tcx hir::Expr<'tcx>, + base: &'tcx hir::Expr<'tcx>, + field: Ident, + ) -> Ty<'tcx> { + debug!("check_field(expr: {:?}, base: {:?}, field: {:?})", expr, base, field); + let expr_t = self.check_expr(base); + let expr_t = self.structurally_resolved_type(base.span, expr_t); + let mut private_candidate = None; + let mut autoderef = self.autoderef(expr.span, expr_t); + while let Some((base_t, _)) = autoderef.next() { + debug!("base_t: {:?}", base_t); + match base_t.kind() { + ty::Adt(base_def, substs) if !base_def.is_enum() => { + debug!("struct named {:?}", base_t); + let (ident, def_scope) = + self.tcx.adjust_ident_and_get_scope(field, base_def.did(), self.body_id); + let fields = &base_def.non_enum_variant().fields; + if let Some(index) = fields + .iter() + .position(|f| f.ident(self.tcx).normalize_to_macros_2_0() == ident) + { + let field = &fields[index]; + let field_ty = self.field_ty(expr.span, field, substs); + // Save the index of all fields regardless of their visibility in case + // of error recovery. + self.write_field_index(expr.hir_id, index); + let adjustments = self.adjust_steps(&autoderef); + if field.vis.is_accessible_from(def_scope, self.tcx) { + self.apply_adjustments(base, adjustments); + self.register_predicates(autoderef.into_obligations()); + + self.tcx.check_stability(field.did, Some(expr.hir_id), expr.span, None); + return field_ty; + } + private_candidate = Some((adjustments, base_def.did(), field_ty)); + } + } + ty::Tuple(tys) => { + let fstr = field.as_str(); + if let Ok(index) = fstr.parse::<usize>() { + if fstr == index.to_string() { + if let Some(&field_ty) = tys.get(index) { + let adjustments = self.adjust_steps(&autoderef); + self.apply_adjustments(base, adjustments); + self.register_predicates(autoderef.into_obligations()); + + self.write_field_index(expr.hir_id, index); + return field_ty; + } + } + } + } + _ => {} + } + } + self.structurally_resolved_type(autoderef.span(), autoderef.final_ty(false)); + + if let Some((adjustments, did, field_ty)) = private_candidate { + // (#90483) apply adjustments to avoid ExprUseVisitor from + // creating erroneous projection. + self.apply_adjustments(base, adjustments); + self.ban_private_field_access(expr, expr_t, field, did); + return field_ty; + } + + if field.name == kw::Empty { + } else if self.method_exists(field, expr_t, expr.hir_id, true) { + self.ban_take_value_of_method(expr, expr_t, field); + } else if !expr_t.is_primitive_ty() { + self.ban_nonexisting_field(field, base, expr, expr_t); + } else { + let field_name = field.to_string(); + let mut err = type_error_struct!( + self.tcx().sess, + field.span, + expr_t, + E0610, + "`{expr_t}` is a primitive type and therefore doesn't have fields", + ); + let is_valid_suffix = |field: String| { + if field == "f32" || field == "f64" { + return true; + } + let mut chars = field.chars().peekable(); + match chars.peek() { + Some('e') | Some('E') => { + chars.next(); + if let Some(c) = chars.peek() + && !c.is_numeric() && *c != '-' && *c != '+' + { + return false; + } + while let Some(c) = chars.peek() { + if !c.is_numeric() { + break; + } + chars.next(); + } + } + _ => (), + } + let suffix = chars.collect::<String>(); + suffix.is_empty() || suffix == "f32" || suffix == "f64" + }; + if let ty::Infer(ty::IntVar(_)) = expr_t.kind() + && let ExprKind::Lit(Spanned { + node: ast::LitKind::Int(_, ast::LitIntType::Unsuffixed), + .. + }) = base.kind + && !base.span.from_expansion() + && is_valid_suffix(field_name) + { + err.span_suggestion_verbose( + field.span.shrink_to_lo(), + "If the number is meant to be a floating point number, consider adding a `0` after the period", + '0', + Applicability::MaybeIncorrect, + ); + } + err.emit(); + } + + self.tcx().ty_error() + } + + fn check_call_constructor<G: EmissionGuarantee>( + &self, + err: &mut DiagnosticBuilder<'_, G>, + base: &'tcx hir::Expr<'tcx>, + def_id: DefId, + ) { + if let Some(local_id) = def_id.as_local() { + let hir_id = self.tcx.hir().local_def_id_to_hir_id(local_id); + let node = self.tcx.hir().get(hir_id); + + if let Some(fields) = node.tuple_fields() { + let kind = match self.tcx.opt_def_kind(local_id) { + Some(DefKind::Ctor(of, _)) => of, + _ => return, + }; + + suggest_call_constructor(base.span, kind, fields.len(), err); + } + } else { + // The logic here isn't smart but `associated_item_def_ids` + // doesn't work nicely on local. + if let DefKind::Ctor(of, _) = self.tcx.def_kind(def_id) { + let parent_def_id = self.tcx.parent(def_id); + let fields = self.tcx.associated_item_def_ids(parent_def_id); + suggest_call_constructor(base.span, of, fields.len(), err); + } + } + } + + fn suggest_await_on_field_access( + &self, + err: &mut Diagnostic, + field_ident: Ident, + base: &'tcx hir::Expr<'tcx>, + ty: Ty<'tcx>, + ) { + let output_ty = match self.get_impl_future_output_ty(ty) { + Some(output_ty) => self.resolve_vars_if_possible(output_ty), + _ => return, + }; + let mut add_label = true; + if let ty::Adt(def, _) = output_ty.skip_binder().kind() { + // no field access on enum type + if !def.is_enum() { + if def + .non_enum_variant() + .fields + .iter() + .any(|field| field.ident(self.tcx) == field_ident) + { + add_label = false; + err.span_label( + field_ident.span, + "field not available in `impl Future`, but it is available in its `Output`", + ); + err.span_suggestion_verbose( + base.span.shrink_to_hi(), + "consider `await`ing on the `Future` and access the field of its `Output`", + ".await", + Applicability::MaybeIncorrect, + ); + } + } + } + if add_label { + err.span_label(field_ident.span, &format!("field not found in `{ty}`")); + } + } + + fn ban_nonexisting_field( + &self, + field: Ident, + base: &'tcx hir::Expr<'tcx>, + expr: &'tcx hir::Expr<'tcx>, + expr_t: Ty<'tcx>, + ) { + debug!( + "ban_nonexisting_field: field={:?}, base={:?}, expr={:?}, expr_ty={:?}", + field, base, expr, expr_t + ); + let mut err = self.no_such_field_err(field, expr_t, base.hir_id); + + match *expr_t.peel_refs().kind() { + ty::Array(_, len) => { + self.maybe_suggest_array_indexing(&mut err, expr, base, field, len); + } + ty::RawPtr(..) => { + self.suggest_first_deref_field(&mut err, expr, base, field); + } + ty::Adt(def, _) if !def.is_enum() => { + self.suggest_fields_on_recordish(&mut err, def, field, expr.span); + } + ty::Param(param_ty) => { + self.point_at_param_definition(&mut err, param_ty); + } + ty::Opaque(_, _) => { + self.suggest_await_on_field_access(&mut err, field, base, expr_t.peel_refs()); + } + ty::FnDef(def_id, _) => { + self.check_call_constructor(&mut err, base, def_id); + } + _ => {} + } + + if field.name == kw::Await { + // We know by construction that `<expr>.await` is either on Rust 2015 + // or results in `ExprKind::Await`. Suggest switching the edition to 2018. + err.note("to `.await` a `Future`, switch to Rust 2018 or later"); + err.help_use_latest_edition(); + } + + err.emit(); + } + + fn ban_private_field_access( + &self, + expr: &hir::Expr<'_>, + expr_t: Ty<'tcx>, + field: Ident, + base_did: DefId, + ) { + let struct_path = self.tcx().def_path_str(base_did); + let kind_name = self.tcx().def_kind(base_did).descr(base_did); + let mut err = struct_span_err!( + self.tcx().sess, + field.span, + E0616, + "field `{field}` of {kind_name} `{struct_path}` is private", + ); + err.span_label(field.span, "private field"); + // Also check if an accessible method exists, which is often what is meant. + if self.method_exists(field, expr_t, expr.hir_id, false) && !self.expr_in_place(expr.hir_id) + { + self.suggest_method_call( + &mut err, + &format!("a method `{field}` also exists, call it with parentheses"), + field, + expr_t, + expr, + None, + ); + } + err.emit(); + } + + fn ban_take_value_of_method(&self, expr: &hir::Expr<'_>, expr_t: Ty<'tcx>, field: Ident) { + let mut err = type_error_struct!( + self.tcx().sess, + field.span, + expr_t, + E0615, + "attempted to take value of method `{field}` on type `{expr_t}`", + ); + err.span_label(field.span, "method, not a field"); + let expr_is_call = + if let hir::Node::Expr(hir::Expr { kind: ExprKind::Call(callee, _args), .. }) = + self.tcx.hir().get(self.tcx.hir().get_parent_node(expr.hir_id)) + { + expr.hir_id == callee.hir_id + } else { + false + }; + let expr_snippet = + self.tcx.sess.source_map().span_to_snippet(expr.span).unwrap_or_default(); + let is_wrapped = expr_snippet.starts_with('(') && expr_snippet.ends_with(')'); + let after_open = expr.span.lo() + rustc_span::BytePos(1); + let before_close = expr.span.hi() - rustc_span::BytePos(1); + + if expr_is_call && is_wrapped { + err.multipart_suggestion( + "remove wrapping parentheses to call the method", + vec![ + (expr.span.with_hi(after_open), String::new()), + (expr.span.with_lo(before_close), String::new()), + ], + Applicability::MachineApplicable, + ); + } else if !self.expr_in_place(expr.hir_id) { + // Suggest call parentheses inside the wrapping parentheses + let span = if is_wrapped { + expr.span.with_lo(after_open).with_hi(before_close) + } else { + expr.span + }; + self.suggest_method_call( + &mut err, + "use parentheses to call the method", + field, + expr_t, + expr, + Some(span), + ); + } else { + let mut found = false; + + if let ty::RawPtr(ty_and_mut) = expr_t.kind() + && let ty::Adt(adt_def, _) = ty_and_mut.ty.kind() + { + if adt_def.variants().len() == 1 + && adt_def + .variants() + .iter() + .next() + .unwrap() + .fields + .iter() + .any(|f| f.ident(self.tcx) == field) + { + if let Some(dot_loc) = expr_snippet.rfind('.') { + found = true; + err.span_suggestion( + expr.span.with_hi(expr.span.lo() + BytePos::from_usize(dot_loc)), + "to access the field, dereference first", + format!("(*{})", &expr_snippet[0..dot_loc]), + Applicability::MaybeIncorrect, + ); + } + } + } + + if !found { + err.help("methods are immutable and cannot be assigned to"); + } + } + + err.emit(); + } + + fn point_at_param_definition(&self, err: &mut Diagnostic, param: ty::ParamTy) { + let generics = self.tcx.generics_of(self.body_id.owner.to_def_id()); + let generic_param = generics.type_param(¶m, self.tcx); + if let ty::GenericParamDefKind::Type { synthetic: true, .. } = generic_param.kind { + return; + } + let param_def_id = generic_param.def_id; + let param_hir_id = match param_def_id.as_local() { + Some(x) => self.tcx.hir().local_def_id_to_hir_id(x), + None => return, + }; + let param_span = self.tcx.hir().span(param_hir_id); + let param_name = self.tcx.hir().ty_param_name(param_def_id.expect_local()); + + err.span_label(param_span, &format!("type parameter '{param_name}' declared here")); + } + + fn suggest_fields_on_recordish( + &self, + err: &mut Diagnostic, + def: ty::AdtDef<'tcx>, + field: Ident, + access_span: Span, + ) { + if let Some(suggested_field_name) = + self.suggest_field_name(def.non_enum_variant(), field.name, vec![], access_span) + { + err.span_suggestion( + field.span, + "a field with a similar name exists", + suggested_field_name, + Applicability::MaybeIncorrect, + ); + } else { + err.span_label(field.span, "unknown field"); + let struct_variant_def = def.non_enum_variant(); + let field_names = self.available_field_names(struct_variant_def, access_span); + if !field_names.is_empty() { + err.note(&format!( + "available fields are: {}", + self.name_series_display(field_names), + )); + } + } + } + + fn maybe_suggest_array_indexing( + &self, + err: &mut Diagnostic, + expr: &hir::Expr<'_>, + base: &hir::Expr<'_>, + field: Ident, + len: ty::Const<'tcx>, + ) { + if let (Some(len), Ok(user_index)) = + (len.try_eval_usize(self.tcx, self.param_env), field.as_str().parse::<u64>()) + && let Ok(base) = self.tcx.sess.source_map().span_to_snippet(base.span) + { + let help = "instead of using tuple indexing, use array indexing"; + let suggestion = format!("{base}[{field}]"); + let applicability = if len < user_index { + Applicability::MachineApplicable + } else { + Applicability::MaybeIncorrect + }; + err.span_suggestion(expr.span, help, suggestion, applicability); + } + } + + fn suggest_first_deref_field( + &self, + err: &mut Diagnostic, + expr: &hir::Expr<'_>, + base: &hir::Expr<'_>, + field: Ident, + ) { + if let Ok(base) = self.tcx.sess.source_map().span_to_snippet(base.span) { + let msg = format!("`{base}` is a raw pointer; try dereferencing it"); + let suggestion = format!("(*{base}).{field}"); + err.span_suggestion(expr.span, &msg, suggestion, Applicability::MaybeIncorrect); + } + } + + fn no_such_field_err( + &self, + field: Ident, + expr_t: Ty<'tcx>, + id: HirId, + ) -> DiagnosticBuilder<'_, ErrorGuaranteed> { + let span = field.span; + debug!("no_such_field_err(span: {:?}, field: {:?}, expr_t: {:?})", span, field, expr_t); + + let mut err = type_error_struct!( + self.tcx().sess, + field.span, + expr_t, + E0609, + "no field `{field}` on type `{expr_t}`", + ); + + // try to add a suggestion in case the field is a nested field of a field of the Adt + if let Some((fields, substs)) = self.get_field_candidates(span, expr_t) { + for candidate_field in fields.iter() { + if let Some(mut field_path) = self.check_for_nested_field_satisfying( + span, + &|candidate_field, _| candidate_field.ident(self.tcx()) == field, + candidate_field, + substs, + vec![], + self.tcx.parent_module(id).to_def_id(), + ) { + // field_path includes `field` that we're looking for, so pop it. + field_path.pop(); + + let field_path_str = field_path + .iter() + .map(|id| id.name.to_ident_string()) + .collect::<Vec<String>>() + .join("."); + debug!("field_path_str: {:?}", field_path_str); + + err.span_suggestion_verbose( + field.span.shrink_to_lo(), + "one of the expressions' fields has a field of the same name", + format!("{field_path_str}."), + Applicability::MaybeIncorrect, + ); + } + } + } + err + } + + pub(crate) fn get_field_candidates( + &self, + span: Span, + base_t: Ty<'tcx>, + ) -> Option<(&[ty::FieldDef], SubstsRef<'tcx>)> { + debug!("get_field_candidates(span: {:?}, base_t: {:?}", span, base_t); + + for (base_t, _) in self.autoderef(span, base_t) { + match base_t.kind() { + ty::Adt(base_def, substs) if !base_def.is_enum() => { + let fields = &base_def.non_enum_variant().fields; + // For compile-time reasons put a limit on number of fields we search + if fields.len() > 100 { + return None; + } + return Some((fields, substs)); + } + _ => {} + } + } + None + } + + /// This method is called after we have encountered a missing field error to recursively + /// search for the field + pub(crate) fn check_for_nested_field_satisfying( + &self, + span: Span, + matches: &impl Fn(&ty::FieldDef, Ty<'tcx>) -> bool, + candidate_field: &ty::FieldDef, + subst: SubstsRef<'tcx>, + mut field_path: Vec<Ident>, + id: DefId, + ) -> Option<Vec<Ident>> { + debug!( + "check_for_nested_field_satisfying(span: {:?}, candidate_field: {:?}, field_path: {:?}", + span, candidate_field, field_path + ); + + if field_path.len() > 3 { + // For compile-time reasons and to avoid infinite recursion we only check for fields + // up to a depth of three + None + } else { + // recursively search fields of `candidate_field` if it's a ty::Adt + field_path.push(candidate_field.ident(self.tcx).normalize_to_macros_2_0()); + let field_ty = candidate_field.ty(self.tcx, subst); + if let Some((nested_fields, subst)) = self.get_field_candidates(span, field_ty) { + for field in nested_fields.iter() { + if field.vis.is_accessible_from(id, self.tcx) { + if matches(candidate_field, field_ty) { + return Some(field_path); + } else if let Some(field_path) = self.check_for_nested_field_satisfying( + span, + matches, + field, + subst, + field_path.clone(), + id, + ) { + return Some(field_path); + } + } + } + } + None + } + } + + fn check_expr_index( + &self, + base: &'tcx hir::Expr<'tcx>, + idx: &'tcx hir::Expr<'tcx>, + expr: &'tcx hir::Expr<'tcx>, + ) -> Ty<'tcx> { + let base_t = self.check_expr(&base); + let idx_t = self.check_expr(&idx); + + if base_t.references_error() { + base_t + } else if idx_t.references_error() { + idx_t + } else { + let base_t = self.structurally_resolved_type(base.span, base_t); + match self.lookup_indexing(expr, base, base_t, idx, idx_t) { + Some((index_ty, element_ty)) => { + // two-phase not needed because index_ty is never mutable + self.demand_coerce(idx, idx_t, index_ty, None, AllowTwoPhase::No); + self.select_obligations_where_possible(false, |errors| { + self.point_at_index_if_possible(errors, idx.span) + }); + element_ty + } + None => { + let mut err = type_error_struct!( + self.tcx.sess, + expr.span, + base_t, + E0608, + "cannot index into a value of type `{base_t}`", + ); + // Try to give some advice about indexing tuples. + if let ty::Tuple(..) = base_t.kind() { + let mut needs_note = true; + // If the index is an integer, we can show the actual + // fixed expression: + if let ExprKind::Lit(ref lit) = idx.kind { + if let ast::LitKind::Int(i, ast::LitIntType::Unsuffixed) = lit.node { + let snip = self.tcx.sess.source_map().span_to_snippet(base.span); + if let Ok(snip) = snip { + err.span_suggestion( + expr.span, + "to access tuple elements, use", + format!("{snip}.{i}"), + Applicability::MachineApplicable, + ); + needs_note = false; + } + } + } + if needs_note { + err.help( + "to access tuple elements, use tuple indexing \ + syntax (e.g., `tuple.0`)", + ); + } + } + err.emit(); + self.tcx.ty_error() + } + } + } + } + + fn point_at_index_if_possible( + &self, + errors: &mut Vec<traits::FulfillmentError<'tcx>>, + span: Span, + ) { + for error in errors { + match error.obligation.predicate.kind().skip_binder() { + ty::PredicateKind::Trait(predicate) + if self.tcx.is_diagnostic_item(sym::SliceIndex, predicate.trait_ref.def_id) => { + } + _ => continue, + } + error.obligation.cause.span = span; + } + } + + fn check_expr_yield( + &self, + value: &'tcx hir::Expr<'tcx>, + expr: &'tcx hir::Expr<'tcx>, + src: &'tcx hir::YieldSource, + ) -> Ty<'tcx> { + match self.resume_yield_tys { + Some((resume_ty, yield_ty)) => { + self.check_expr_coercable_to_type(&value, yield_ty, None); + + resume_ty + } + // Given that this `yield` expression was generated as a result of lowering a `.await`, + // we know that the yield type must be `()`; however, the context won't contain this + // information. Hence, we check the source of the yield expression here and check its + // value's type against `()` (this check should always hold). + None if src.is_await() => { + self.check_expr_coercable_to_type(&value, self.tcx.mk_unit(), None); + self.tcx.mk_unit() + } + _ => { + self.tcx.sess.emit_err(YieldExprOutsideOfGenerator { span: expr.span }); + // Avoid expressions without types during writeback (#78653). + self.check_expr(value); + self.tcx.mk_unit() + } + } + } + + fn check_expr_asm_operand(&self, expr: &'tcx hir::Expr<'tcx>, is_input: bool) { + let needs = if is_input { Needs::None } else { Needs::MutPlace }; + let ty = self.check_expr_with_needs(expr, needs); + self.require_type_is_sized(ty, expr.span, traits::InlineAsmSized); + + if !is_input && !expr.is_syntactic_place_expr() { + let mut err = self.tcx.sess.struct_span_err(expr.span, "invalid asm output"); + err.span_label(expr.span, "cannot assign to this expression"); + err.emit(); + } + + // If this is an input value, we require its type to be fully resolved + // at this point. This allows us to provide helpful coercions which help + // pass the type candidate list in a later pass. + // + // We don't require output types to be resolved at this point, which + // allows them to be inferred based on how they are used later in the + // function. + if is_input { + let ty = self.structurally_resolved_type(expr.span, ty); + match *ty.kind() { + ty::FnDef(..) => { + let fnptr_ty = self.tcx.mk_fn_ptr(ty.fn_sig(self.tcx)); + self.demand_coerce(expr, ty, fnptr_ty, None, AllowTwoPhase::No); + } + ty::Ref(_, base_ty, mutbl) => { + let ptr_ty = self.tcx.mk_ptr(ty::TypeAndMut { ty: base_ty, mutbl }); + self.demand_coerce(expr, ty, ptr_ty, None, AllowTwoPhase::No); + } + _ => {} + } + } + } + + fn check_expr_asm(&self, asm: &'tcx hir::InlineAsm<'tcx>) -> Ty<'tcx> { + for (op, _op_sp) in asm.operands { + match op { + hir::InlineAsmOperand::In { expr, .. } => { + self.check_expr_asm_operand(expr, true); + } + hir::InlineAsmOperand::Out { expr: Some(expr), .. } + | hir::InlineAsmOperand::InOut { expr, .. } => { + self.check_expr_asm_operand(expr, false); + } + hir::InlineAsmOperand::Out { expr: None, .. } => {} + hir::InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => { + self.check_expr_asm_operand(in_expr, true); + if let Some(out_expr) = out_expr { + self.check_expr_asm_operand(out_expr, false); + } + } + // `AnonConst`s have their own body and is type-checked separately. + // As they don't flow into the type system we don't need them to + // be well-formed. + hir::InlineAsmOperand::Const { .. } | hir::InlineAsmOperand::SymFn { .. } => {} + hir::InlineAsmOperand::SymStatic { .. } => {} + } + } + if asm.options.contains(ast::InlineAsmOptions::NORETURN) { + self.tcx.types.never + } else { + self.tcx.mk_unit() + } + } +} + +pub(super) fn ty_kind_suggestion(ty: Ty<'_>) -> Option<&'static str> { + Some(match ty.kind() { + ty::Bool => "true", + ty::Char => "'a'", + ty::Int(_) | ty::Uint(_) => "42", + ty::Float(_) => "3.14159", + ty::Error(_) | ty::Never => return None, + _ => "value", + }) +} |