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-rw-r--r--compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs1510
1 files changed, 1510 insertions, 0 deletions
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
new file mode 100644
index 000000000..3a8093345
--- /dev/null
+++ b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
@@ -0,0 +1,1510 @@
+use crate::astconv::{
+ AstConv, CreateSubstsForGenericArgsCtxt, ExplicitLateBound, GenericArgCountMismatch,
+ GenericArgCountResult, IsMethodCall, PathSeg,
+};
+use crate::check::callee::{self, DeferredCallResolution};
+use crate::check::method::{self, MethodCallee, SelfSource};
+use crate::check::rvalue_scopes;
+use crate::check::{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_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::subst::{
+ self, GenericArgKind, InternalSubsts, Subst, SubstsRef, UserSelfTy, UserSubsts,
+};
+use rustc_middle::ty::visit::TypeVisitable;
+use rustc_middle::ty::{
+ self, AdtKind, CanonicalUserType, DefIdTree, EarlyBinder, GenericParamDefKind, ToPolyTraitRef,
+ ToPredicate, Ty, UserType,
+};
+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::InferCtxtExt 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);
+
+ self.tcx().struct_span_lint_hir(lint::builtin::UNREACHABLE_CODE, id, span, |lint| {
+ let msg = format!("unreachable {}", kind);
+ lint.build(&msg)
+ .span_label(span, &msg)
+ .span_label(
+ orig_span,
+ custom_note
+ .unwrap_or("any code following this expression is unreachable"),
+ )
+ .emit();
+ })
+ }
+ }
+ }
+
+ /// 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")]
+ pub(in super::super) fn resolve_vars_with_obligations_and_mutate_fulfillment(
+ &self,
+ mut ty: Ty<'tcx>,
+ mutate_fulfillment_errors: impl Fn(&mut Vec<traits::FulfillmentError<'tcx>>),
+ ) -> Ty<'tcx> {
+ // No Infer()? Nothing needs doing.
+ if !ty.has_infer_types_or_consts() {
+ 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_infer_types_or_consts() {
+ 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);
+ ty = self.resolve_vars_if_possible(ty);
+
+ debug!(?ty);
+ 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<DeferredCallResolution<'tcx>> {
+ 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::<u32>(...)` -- 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<UserSelfTy<'tcx>>,
+ ) {
+ 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<Adjustment<'tcx>>) {
+ 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 <expr>`.
+ // In this case implicit use of `Deref` and `Index` within `<expr>` 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<T>(&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<Span>) {
+ let bounds = self.tcx.predicates_of(def_id);
+ let spans: Vec<Span> = 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<T>(&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<T>(
+ &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<T>(
+ &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_pred: 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 = <dyn AstConv<'_>>::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) => self.to_const(anon_const),
+ }
+ }
+
+ pub fn to_const(&self, ast_c: &hir::AnonConst) -> ty::Const<'tcx> {
+ let const_def_id = self.tcx.hir().local_def_id(ast_c.hir_id);
+ let c = ty::Const::from_anon_const(self.tcx, const_def_id);
+ self.register_wf_obligation(
+ c.into(),
+ self.tcx.hir().span(ast_c.hir_id),
+ ObligationCauseCode::WellFormed(None),
+ );
+ 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: 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<Ty<'tcx>> {
+ 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: subst::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 <none> 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::check::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 errors = self.fulfillment_cx.borrow_mut().select_all_or_error(&self);
+
+ if !errors.is_empty() {
+ self.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<traits::FulfillmentError<'tcx>>),
+ ) {
+ let mut result = self.fulfillment_cx.borrow_mut().select_where_possible(self);
+ if !result.is_empty() {
+ mutate_fulfillment_errors(&mut result);
+ self.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<Item = (ty::PolyTraitRef<'tcx>, 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<Ty<'tcx>> {
+ 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<Vec<Ty<'tcx>>> {
+ 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 = <dyn TraitEngine<'_>>::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<hir::HirId>,
+ ) -> (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)));
+ self.add_required_obligations_with_code(
+ span,
+ def_id,
+ &substs,
+ match lang_item {
+ hir::LangItem::IntoFutureIntoFuture => {
+ ObligationCauseCode::AwaitableExpr(expr_hir_id)
+ }
+ hir::LangItem::IteratorNext | hir::LangItem::IntoIterIntoIter => {
+ ObligationCauseCode::ForLoopIterator
+ }
+ hir::LangItem::TryTraitFromOutput
+ | hir::LangItem::TryTraitFromResidual
+ | hir::LangItem::TryTraitBranch => ObligationCauseCode::QuestionMark,
+ _ => traits::ItemObligation(def_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<Ty<'tcx>>, &'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.
+ (<dyn AstConv<'_>>::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<Ty<'tcx>>,
+ 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) => <dyn AstConv<'_>>::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 {
+ // `<T>::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 = <dyn AstConv<'_>>::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 = <dyn AstConv<'_>>::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<usize>,
+ 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<'_>,
+ ) -> subst::GenericArg<'tcx> {
+ match (&param.kind, arg) {
+ (GenericParamDefKind::Lifetime, GenericArg::Lifetime(lt)) => {
+ <dyn AstConv<'_>>::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<&[subst::GenericArg<'tcx>]>,
+ param: &ty::GenericParamDef,
+ infer_args: bool,
+ ) -> subst::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(|| {
+ <dyn AstConv<'_>>::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(span, def_id, &substs);
+
+ // 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<T>::method` and `<Foo<T>>::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(
+ &self,
+ span: Span,
+ def_id: DefId,
+ substs: &SubstsRef<'tcx>,
+ ) {
+ self.add_required_obligations_with_code(
+ span,
+ def_id,
+ substs,
+ traits::ItemObligation(def_id),
+ )
+ }
+
+ #[tracing::instrument(level = "debug", skip(self, span, def_id, substs))]
+ fn add_required_obligations_with_code(
+ &self,
+ span: Span,
+ def_id: DefId,
+ substs: &SubstsRef<'tcx>,
+ code: ObligationCauseCode<'tcx>,
+ ) {
+ let (bounds, _) = self.instantiate_bounds(span, def_id, &substs);
+
+ for obligation in traits::predicates_for_generics(
+ traits::ObligationCause::new(span, self.body_id, code),
+ self.param_env,
+ bounds,
+ ) {
+ 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.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<F: FnOnce() -> 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
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-12 10:54:04 +0000