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-rw-r--r--crates/ra_hir/src/ty/infer.rs1164
1 files changed, 26 insertions, 1138 deletions
diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index ca9aefc42..ebaff998e 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -14,7 +14,6 @@
14//! the `ena` crate, which is extracted from rustc. 14//! the `ena` crate, which is extracted from rustc.
15 15
16use std::borrow::Cow; 16use std::borrow::Cow;
17use std::iter::{repeat, repeat_with};
18use std::mem; 17use std::mem;
19use std::ops::Index; 18use std::ops::Index;
20use std::sync::Arc; 19use std::sync::Arc;
@@ -27,33 +26,39 @@ use ra_prof::profile;
27use test_utils::tested_by; 26use test_utils::tested_by;
28 27
29use super::{ 28use super::{
30 autoderef, lower, method_resolution, op, primitive, 29 lower, primitive,
31 traits::{Guidance, Obligation, ProjectionPredicate, Solution}, 30 traits::{Guidance, Obligation, ProjectionPredicate, Solution},
32 ApplicationTy, CallableDef, InEnvironment, ProjectionTy, Substs, TraitEnvironment, TraitRef, 31 ApplicationTy, InEnvironment, ProjectionTy, Substs, TraitEnvironment, TraitRef, Ty, TypableDef,
33 Ty, TypableDef, TypeCtor, TypeWalk, 32 TypeCtor, TypeWalk,
34}; 33};
35use crate::{ 34use crate::{
36 adt::VariantDef, 35 adt::VariantDef,
37 code_model::TypeAlias, 36 code_model::TypeAlias,
38 db::HirDatabase, 37 db::HirDatabase,
39 diagnostics::DiagnosticSink, 38 diagnostics::DiagnosticSink,
40 expr::{ 39 expr::{BindingAnnotation, Body, ExprId, PatId},
41 self, Array, BinaryOp, BindingAnnotation, Body, Expr, ExprId, Literal, Pat, PatId,
42 RecordFieldPat, Statement, UnaryOp,
43 },
44 generics::{GenericParams, HasGenericParams},
45 lang_item::LangItemTarget,
46 name, 40 name,
47 nameres::Namespace, 41 path::known,
48 path::{known, GenericArg, GenericArgs},
49 resolve::{Resolver, TypeNs}, 42 resolve::{Resolver, TypeNs},
50 ty::infer::diagnostics::InferenceDiagnostic, 43 ty::infer::diagnostics::InferenceDiagnostic,
51 type_ref::{Mutability, TypeRef}, 44 type_ref::{Mutability, TypeRef},
52 Adt, AssocItem, ConstData, DefWithBody, FnData, Function, HasBody, Name, Path, StructField, 45 Adt, AssocItem, ConstData, DefWithBody, FnData, Function, HasBody, Path, StructField,
53}; 46};
54 47
48macro_rules! ty_app {
49 ($ctor:pat, $param:pat) => {
50 crate::ty::Ty::Apply(crate::ty::ApplicationTy { ctor: $ctor, parameters: $param })
51 };
52 ($ctor:pat) => {
53 ty_app!($ctor, _)
54 };
55}
56
55mod unify; 57mod unify;
56mod path; 58mod path;
59mod expr;
60mod pat;
61mod coerce;
57 62
58/// The entry point of type inference. 63/// The entry point of type inference.
59pub fn infer_query(db: &impl HirDatabase, def: DefWithBody) -> Arc<InferenceResult> { 64pub fn infer_query(db: &impl HirDatabase, def: DefWithBody) -> Arc<InferenceResult> {
@@ -197,15 +202,6 @@ struct InferenceContext<'a, D: HirDatabase> {
197 coerce_unsized_map: FxHashMap<(TypeCtor, TypeCtor), usize>, 202 coerce_unsized_map: FxHashMap<(TypeCtor, TypeCtor), usize>,
198} 203}
199 204
200macro_rules! ty_app {
201 ($ctor:pat, $param:pat) => {
202 Ty::Apply(ApplicationTy { ctor: $ctor, parameters: $param })
203 };
204 ($ctor:pat) => {
205 ty_app!($ctor, _)
206 };
207}
208
209impl<'a, D: HirDatabase> InferenceContext<'a, D> { 205impl<'a, D: HirDatabase> InferenceContext<'a, D> {
210 fn new(db: &'a D, body: Arc<Body>, resolver: Resolver) -> Self { 206 fn new(db: &'a D, body: Arc<Body>, resolver: Resolver) -> Self {
211 InferenceContext { 207 InferenceContext {
@@ -221,45 +217,6 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
221 } 217 }
222 } 218 }
223 219
224 fn init_coerce_unsized_map(
225 db: &'a D,
226 resolver: &Resolver,
227 ) -> FxHashMap<(TypeCtor, TypeCtor), usize> {
228 let krate = resolver.krate().unwrap();
229 let impls = match db.lang_item(krate, "coerce_unsized".into()) {
230 Some(LangItemTarget::Trait(trait_)) => db.impls_for_trait(krate, trait_),
231 _ => return FxHashMap::default(),
232 };
233
234 impls
235 .iter()
236 .filter_map(|impl_block| {
237 // `CoerseUnsized` has one generic parameter for the target type.
238 let trait_ref = impl_block.target_trait_ref(db)?;
239 let cur_from_ty = trait_ref.substs.0.get(0)?;
240 let cur_to_ty = trait_ref.substs.0.get(1)?;
241
242 match (&cur_from_ty, cur_to_ty) {
243 (ty_app!(ctor1, st1), ty_app!(ctor2, st2)) => {
244 // FIXME: We return the first non-equal bound as the type parameter to coerce to unsized type.
245 // This works for smart-pointer-like coercion, which covers all impls from std.
246 st1.iter().zip(st2.iter()).enumerate().find_map(|(i, (ty1, ty2))| {
247 match (ty1, ty2) {
248 (Ty::Param { idx: p1, .. }, Ty::Param { idx: p2, .. })
249 if p1 != p2 =>
250 {
251 Some(((*ctor1, *ctor2), i))
252 }
253 _ => None,
254 }
255 })
256 }
257 _ => None,
258 }
259 })
260 .collect()
261 }
262
263 fn resolve_all(mut self) -> InferenceResult { 220 fn resolve_all(mut self) -> InferenceResult {
264 // FIXME resolve obligations as well (use Guidance if necessary) 221 // FIXME resolve obligations as well (use Guidance if necessary)
265 let mut result = mem::replace(&mut self.result, InferenceResult::default()); 222 let mut result = mem::replace(&mut self.result, InferenceResult::default());
@@ -457,7 +414,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
457 // recursive type 414 // recursive type
458 return tv.fallback_value(); 415 return tv.fallback_value();
459 } 416 }
460 if let Some(known_ty) = self.var_unification_table.probe_value(inner).known() { 417 if let Some(known_ty) =
418 self.var_unification_table.inlined_probe_value(inner).known()
419 {
461 // known_ty may contain other variables that are known by now 420 // known_ty may contain other variables that are known by now
462 tv_stack.push(inner); 421 tv_stack.push(inner);
463 let result = self.resolve_ty_as_possible(tv_stack, known_ty.clone()); 422 let result = self.resolve_ty_as_possible(tv_stack, known_ty.clone());
@@ -485,7 +444,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
485 match &*ty { 444 match &*ty {
486 Ty::Infer(tv) => { 445 Ty::Infer(tv) => {
487 let inner = tv.to_inner(); 446 let inner = tv.to_inner();
488 match self.var_unification_table.probe_value(inner).known() { 447 match self.var_unification_table.inlined_probe_value(inner).known() {
489 Some(known_ty) => { 448 Some(known_ty) => {
490 // The known_ty can't be a type var itself 449 // The known_ty can't be a type var itself
491 ty = Cow::Owned(known_ty.clone()); 450 ty = Cow::Owned(known_ty.clone());
@@ -533,7 +492,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
533 // recursive type 492 // recursive type
534 return tv.fallback_value(); 493 return tv.fallback_value();
535 } 494 }
536 if let Some(known_ty) = self.var_unification_table.probe_value(inner).known() { 495 if let Some(known_ty) =
496 self.var_unification_table.inlined_probe_value(inner).known()
497 {
537 // known_ty may contain other variables that are known by now 498 // known_ty may contain other variables that are known by now
538 tv_stack.push(inner); 499 tv_stack.push(inner);
539 let result = self.resolve_ty_completely(tv_stack, known_ty.clone()); 500 let result = self.resolve_ty_completely(tv_stack, known_ty.clone());
@@ -559,6 +520,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
559 match resolver.resolve_path_in_type_ns_fully(self.db, &path) { 520 match resolver.resolve_path_in_type_ns_fully(self.db, &path) {
560 Some(TypeNs::Adt(Adt::Struct(it))) => it.into(), 521 Some(TypeNs::Adt(Adt::Struct(it))) => it.into(),
561 Some(TypeNs::Adt(Adt::Union(it))) => it.into(), 522 Some(TypeNs::Adt(Adt::Union(it))) => it.into(),
523 Some(TypeNs::AdtSelfType(adt)) => adt.into(),
562 Some(TypeNs::EnumVariant(it)) => it.into(), 524 Some(TypeNs::EnumVariant(it)) => it.into(),
563 Some(TypeNs::TypeAlias(it)) => it.into(), 525 Some(TypeNs::TypeAlias(it)) => it.into(),
564 526
@@ -594,1080 +556,6 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
594 } 556 }
595 } 557 }
596 558
597 fn infer_tuple_struct_pat(
598 &mut self,
599 path: Option<&Path>,
600 subpats: &[PatId],
601 expected: &Ty,
602 default_bm: BindingMode,
603 ) -> Ty {
604 let (ty, def) = self.resolve_variant(path);
605
606 self.unify(&ty, expected);
607
608 let substs = ty.substs().unwrap_or_else(Substs::empty);
609
610 for (i, &subpat) in subpats.iter().enumerate() {
611 let expected_ty = def
612 .and_then(|d| d.field(self.db, &Name::new_tuple_field(i)))
613 .map_or(Ty::Unknown, |field| field.ty(self.db))
614 .subst(&substs);
615 let expected_ty = self.normalize_associated_types_in(expected_ty);
616 self.infer_pat(subpat, &expected_ty, default_bm);
617 }
618
619 ty
620 }
621
622 fn infer_record_pat(
623 &mut self,
624 path: Option<&Path>,
625 subpats: &[RecordFieldPat],
626 expected: &Ty,
627 default_bm: BindingMode,
628 id: PatId,
629 ) -> Ty {
630 let (ty, def) = self.resolve_variant(path);
631 if let Some(variant) = def {
632 self.write_variant_resolution(id.into(), variant);
633 }
634
635 self.unify(&ty, expected);
636
637 let substs = ty.substs().unwrap_or_else(Substs::empty);
638
639 for subpat in subpats {
640 let matching_field = def.and_then(|it| it.field(self.db, &subpat.name));
641 let expected_ty =
642 matching_field.map_or(Ty::Unknown, |field| field.ty(self.db)).subst(&substs);
643 let expected_ty = self.normalize_associated_types_in(expected_ty);
644 self.infer_pat(subpat.pat, &expected_ty, default_bm);
645 }
646
647 ty
648 }
649
650 fn infer_pat(&mut self, pat: PatId, mut expected: &Ty, mut default_bm: BindingMode) -> Ty {
651 let body = Arc::clone(&self.body); // avoid borrow checker problem
652
653 let is_non_ref_pat = match &body[pat] {
654 Pat::Tuple(..)
655 | Pat::TupleStruct { .. }
656 | Pat::Record { .. }
657 | Pat::Range { .. }
658 | Pat::Slice { .. } => true,
659 // FIXME: Path/Lit might actually evaluate to ref, but inference is unimplemented.
660 Pat::Path(..) | Pat::Lit(..) => true,
661 Pat::Wild | Pat::Bind { .. } | Pat::Ref { .. } | Pat::Missing => false,
662 };
663 if is_non_ref_pat {
664 while let Some((inner, mutability)) = expected.as_reference() {
665 expected = inner;
666 default_bm = match default_bm {
667 BindingMode::Move => BindingMode::Ref(mutability),
668 BindingMode::Ref(Mutability::Shared) => BindingMode::Ref(Mutability::Shared),
669 BindingMode::Ref(Mutability::Mut) => BindingMode::Ref(mutability),
670 }
671 }
672 } else if let Pat::Ref { .. } = &body[pat] {
673 tested_by!(match_ergonomics_ref);
674 // When you encounter a `&pat` pattern, reset to Move.
675 // This is so that `w` is by value: `let (_, &w) = &(1, &2);`
676 default_bm = BindingMode::Move;
677 }
678
679 // Lose mutability.
680 let default_bm = default_bm;
681 let expected = expected;
682
683 let ty = match &body[pat] {
684 Pat::Tuple(ref args) => {
685 let expectations = match expected.as_tuple() {
686 Some(parameters) => &*parameters.0,
687 _ => &[],
688 };
689 let expectations_iter = expectations.iter().chain(repeat(&Ty::Unknown));
690
691 let inner_tys = args
692 .iter()
693 .zip(expectations_iter)
694 .map(|(&pat, ty)| self.infer_pat(pat, ty, default_bm))
695 .collect();
696
697 Ty::apply(TypeCtor::Tuple { cardinality: args.len() as u16 }, Substs(inner_tys))
698 }
699 Pat::Ref { pat, mutability } => {
700 let expectation = match expected.as_reference() {
701 Some((inner_ty, exp_mut)) => {
702 if *mutability != exp_mut {
703 // FIXME: emit type error?
704 }
705 inner_ty
706 }
707 _ => &Ty::Unknown,
708 };
709 let subty = self.infer_pat(*pat, expectation, default_bm);
710 Ty::apply_one(TypeCtor::Ref(*mutability), subty)
711 }
712 Pat::TupleStruct { path: p, args: subpats } => {
713 self.infer_tuple_struct_pat(p.as_ref(), subpats, expected, default_bm)
714 }
715 Pat::Record { path: p, args: fields } => {
716 self.infer_record_pat(p.as_ref(), fields, expected, default_bm, pat)
717 }
718 Pat::Path(path) => {
719 // FIXME use correct resolver for the surrounding expression
720 let resolver = self.resolver.clone();
721 self.infer_path(&resolver, &path, pat.into()).unwrap_or(Ty::Unknown)
722 }
723 Pat::Bind { mode, name: _, subpat } => {
724 let mode = if mode == &BindingAnnotation::Unannotated {
725 default_bm
726 } else {
727 BindingMode::convert(*mode)
728 };
729 let inner_ty = if let Some(subpat) = subpat {
730 self.infer_pat(*subpat, expected, default_bm)
731 } else {
732 expected.clone()
733 };
734 let inner_ty = self.insert_type_vars_shallow(inner_ty);
735
736 let bound_ty = match mode {
737 BindingMode::Ref(mutability) => {
738 Ty::apply_one(TypeCtor::Ref(mutability), inner_ty.clone())
739 }
740 BindingMode::Move => inner_ty.clone(),
741 };
742 let bound_ty = self.resolve_ty_as_possible(&mut vec![], bound_ty);
743 self.write_pat_ty(pat, bound_ty);
744 return inner_ty;
745 }
746 _ => Ty::Unknown,
747 };
748 // use a new type variable if we got Ty::Unknown here
749 let ty = self.insert_type_vars_shallow(ty);
750 self.unify(&ty, expected);
751 let ty = self.resolve_ty_as_possible(&mut vec![], ty);
752 self.write_pat_ty(pat, ty.clone());
753 ty
754 }
755
756 fn substs_for_method_call(
757 &mut self,
758 def_generics: Option<Arc<GenericParams>>,
759 generic_args: Option<&GenericArgs>,
760 receiver_ty: &Ty,
761 ) -> Substs {
762 let (parent_param_count, param_count) =
763 def_generics.as_ref().map_or((0, 0), |g| (g.count_parent_params(), g.params.len()));
764 let mut substs = Vec::with_capacity(parent_param_count + param_count);
765 // Parent arguments are unknown, except for the receiver type
766 if let Some(parent_generics) = def_generics.and_then(|p| p.parent_params.clone()) {
767 for param in &parent_generics.params {
768 if param.name == name::SELF_TYPE {
769 substs.push(receiver_ty.clone());
770 } else {
771 substs.push(Ty::Unknown);
772 }
773 }
774 }
775 // handle provided type arguments
776 if let Some(generic_args) = generic_args {
777 // if args are provided, it should be all of them, but we can't rely on that
778 for arg in generic_args.args.iter().take(param_count) {
779 match arg {
780 GenericArg::Type(type_ref) => {
781 let ty = self.make_ty(type_ref);
782 substs.push(ty);
783 }
784 }
785 }
786 };
787 let supplied_params = substs.len();
788 for _ in supplied_params..parent_param_count + param_count {
789 substs.push(Ty::Unknown);
790 }
791 assert_eq!(substs.len(), parent_param_count + param_count);
792 Substs(substs.into())
793 }
794
795 fn register_obligations_for_call(&mut self, callable_ty: &Ty) {
796 if let Ty::Apply(a_ty) = callable_ty {
797 if let TypeCtor::FnDef(def) = a_ty.ctor {
798 let generic_predicates = self.db.generic_predicates(def.into());
799 for predicate in generic_predicates.iter() {
800 let predicate = predicate.clone().subst(&a_ty.parameters);
801 if let Some(obligation) = Obligation::from_predicate(predicate) {
802 self.obligations.push(obligation);
803 }
804 }
805 // add obligation for trait implementation, if this is a trait method
806 match def {
807 CallableDef::Function(f) => {
808 if let Some(trait_) = f.parent_trait(self.db) {
809 // construct a TraitDef
810 let substs = a_ty.parameters.prefix(
811 trait_.generic_params(self.db).count_params_including_parent(),
812 );
813 self.obligations.push(Obligation::Trait(TraitRef { trait_, substs }));
814 }
815 }
816 CallableDef::Struct(_) | CallableDef::EnumVariant(_) => {}
817 }
818 }
819 }
820 }
821
822 fn infer_method_call(
823 &mut self,
824 tgt_expr: ExprId,
825 receiver: ExprId,
826 args: &[ExprId],
827 method_name: &Name,
828 generic_args: Option<&GenericArgs>,
829 ) -> Ty {
830 let receiver_ty = self.infer_expr(receiver, &Expectation::none());
831 let canonicalized_receiver = self.canonicalizer().canonicalize_ty(receiver_ty.clone());
832 let resolved = method_resolution::lookup_method(
833 &canonicalized_receiver.value,
834 self.db,
835 method_name,
836 &self.resolver,
837 );
838 let (derefed_receiver_ty, method_ty, def_generics) = match resolved {
839 Some((ty, func)) => {
840 let ty = canonicalized_receiver.decanonicalize_ty(ty);
841 self.write_method_resolution(tgt_expr, func);
842 (
843 ty,
844 self.db.type_for_def(func.into(), Namespace::Values),
845 Some(func.generic_params(self.db)),
846 )
847 }
848 None => (receiver_ty, Ty::Unknown, None),
849 };
850 let substs = self.substs_for_method_call(def_generics, generic_args, &derefed_receiver_ty);
851 let method_ty = method_ty.apply_substs(substs);
852 let method_ty = self.insert_type_vars(method_ty);
853 self.register_obligations_for_call(&method_ty);
854 let (expected_receiver_ty, param_tys, ret_ty) = match method_ty.callable_sig(self.db) {
855 Some(sig) => {
856 if !sig.params().is_empty() {
857 (sig.params()[0].clone(), sig.params()[1..].to_vec(), sig.ret().clone())
858 } else {
859 (Ty::Unknown, Vec::new(), sig.ret().clone())
860 }
861 }
862 None => (Ty::Unknown, Vec::new(), Ty::Unknown),
863 };
864 // Apply autoref so the below unification works correctly
865 // FIXME: return correct autorefs from lookup_method
866 let actual_receiver_ty = match expected_receiver_ty.as_reference() {
867 Some((_, mutability)) => Ty::apply_one(TypeCtor::Ref(mutability), derefed_receiver_ty),
868 _ => derefed_receiver_ty,
869 };
870 self.unify(&expected_receiver_ty, &actual_receiver_ty);
871
872 self.check_call_arguments(args, &param_tys);
873 let ret_ty = self.normalize_associated_types_in(ret_ty);
874 ret_ty
875 }
876
877 /// Infer type of expression with possibly implicit coerce to the expected type.
878 /// Return the type after possible coercion.
879 fn infer_expr_coerce(&mut self, expr: ExprId, expected: &Expectation) -> Ty {
880 let ty = self.infer_expr_inner(expr, &expected);
881 let ty = if !self.coerce(&ty, &expected.ty) {
882 self.result
883 .type_mismatches
884 .insert(expr, TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() });
885 // Return actual type when type mismatch.
886 // This is needed for diagnostic when return type mismatch.
887 ty
888 } else if expected.ty == Ty::Unknown {
889 ty
890 } else {
891 expected.ty.clone()
892 };
893
894 self.resolve_ty_as_possible(&mut vec![], ty)
895 }
896
897 /// Merge two types from different branches, with possible implicit coerce.
898 ///
899 /// Note that it is only possible that one type are coerced to another.
900 /// Coercing both types to another least upper bound type is not possible in rustc,
901 /// which will simply result in "incompatible types" error.
902 fn coerce_merge_branch<'t>(&mut self, ty1: &Ty, ty2: &Ty) -> Ty {
903 if self.coerce(ty1, ty2) {
904 ty2.clone()
905 } else if self.coerce(ty2, ty1) {
906 ty1.clone()
907 } else {
908 tested_by!(coerce_merge_fail_fallback);
909 // For incompatible types, we use the latter one as result
910 // to be better recovery for `if` without `else`.
911 ty2.clone()
912 }
913 }
914
915 /// Unify two types, but may coerce the first one to the second one
916 /// using "implicit coercion rules" if needed.
917 ///
918 /// See: https://doc.rust-lang.org/nomicon/coercions.html
919 fn coerce(&mut self, from_ty: &Ty, to_ty: &Ty) -> bool {
920 let from_ty = self.resolve_ty_shallow(from_ty).into_owned();
921 let to_ty = self.resolve_ty_shallow(to_ty);
922 self.coerce_inner(from_ty, &to_ty)
923 }
924
925 fn coerce_inner(&mut self, mut from_ty: Ty, to_ty: &Ty) -> bool {
926 match (&from_ty, to_ty) {
927 // Never type will make type variable to fallback to Never Type instead of Unknown.
928 (ty_app!(TypeCtor::Never), Ty::Infer(InferTy::TypeVar(tv))) => {
929 let var = self.new_maybe_never_type_var();
930 self.var_unification_table.union_value(*tv, TypeVarValue::Known(var));
931 return true;
932 }
933 (ty_app!(TypeCtor::Never), _) => return true,
934
935 // Trivial cases, this should go after `never` check to
936 // avoid infer result type to be never
937 _ => {
938 if self.unify_inner_trivial(&from_ty, &to_ty) {
939 return true;
940 }
941 }
942 }
943
944 // Pointer weakening and function to pointer
945 match (&mut from_ty, to_ty) {
946 // `*mut T`, `&mut T, `&T`` -> `*const T`
947 // `&mut T` -> `&T`
948 // `&mut T` -> `*mut T`
949 (ty_app!(c1@TypeCtor::RawPtr(_)), ty_app!(c2@TypeCtor::RawPtr(Mutability::Shared)))
950 | (ty_app!(c1@TypeCtor::Ref(_)), ty_app!(c2@TypeCtor::RawPtr(Mutability::Shared)))
951 | (ty_app!(c1@TypeCtor::Ref(_)), ty_app!(c2@TypeCtor::Ref(Mutability::Shared)))
952 | (ty_app!(c1@TypeCtor::Ref(Mutability::Mut)), ty_app!(c2@TypeCtor::RawPtr(_))) => {
953 *c1 = *c2;
954 }
955
956 // Illegal mutablity conversion
957 (
958 ty_app!(TypeCtor::RawPtr(Mutability::Shared)),
959 ty_app!(TypeCtor::RawPtr(Mutability::Mut)),
960 )
961 | (
962 ty_app!(TypeCtor::Ref(Mutability::Shared)),
963 ty_app!(TypeCtor::Ref(Mutability::Mut)),
964 ) => return false,
965
966 // `{function_type}` -> `fn()`
967 (ty_app!(TypeCtor::FnDef(_)), ty_app!(TypeCtor::FnPtr { .. })) => {
968 match from_ty.callable_sig(self.db) {
969 None => return false,
970 Some(sig) => {
971 let num_args = sig.params_and_return.len() as u16 - 1;
972 from_ty =
973 Ty::apply(TypeCtor::FnPtr { num_args }, Substs(sig.params_and_return));
974 }
975 }
976 }
977
978 _ => {}
979 }
980
981 if let Some(ret) = self.try_coerce_unsized(&from_ty, &to_ty) {
982 return ret;
983 }
984
985 // Auto Deref if cannot coerce
986 match (&from_ty, to_ty) {
987 // FIXME: DerefMut
988 (ty_app!(TypeCtor::Ref(_), st1), ty_app!(TypeCtor::Ref(_), st2)) => {
989 self.unify_autoderef_behind_ref(&st1[0], &st2[0])
990 }
991
992 // Otherwise, normal unify
993 _ => self.unify(&from_ty, to_ty),
994 }
995 }
996
997 /// Coerce a type using `from_ty: CoerceUnsized<ty_ty>`
998 ///
999 /// See: https://doc.rust-lang.org/nightly/std/marker/trait.CoerceUnsized.html
1000 fn try_coerce_unsized(&mut self, from_ty: &Ty, to_ty: &Ty) -> Option<bool> {
1001 let (ctor1, st1, ctor2, st2) = match (from_ty, to_ty) {
1002 (ty_app!(ctor1, st1), ty_app!(ctor2, st2)) => (ctor1, st1, ctor2, st2),
1003 _ => return None,
1004 };
1005
1006 let coerce_generic_index = *self.coerce_unsized_map.get(&(*ctor1, *ctor2))?;
1007
1008 // Check `Unsize` first
1009 match self.check_unsize_and_coerce(
1010 st1.0.get(coerce_generic_index)?,
1011 st2.0.get(coerce_generic_index)?,
1012 0,
1013 ) {
1014 Some(true) => {}
1015 ret => return ret,
1016 }
1017
1018 let ret = st1
1019 .iter()
1020 .zip(st2.iter())
1021 .enumerate()
1022 .filter(|&(idx, _)| idx != coerce_generic_index)
1023 .all(|(_, (ty1, ty2))| self.unify(ty1, ty2));
1024
1025 Some(ret)
1026 }
1027
1028 /// Check if `from_ty: Unsize<to_ty>`, and coerce to `to_ty` if it holds.
1029 ///
1030 /// It should not be directly called. It is only used by `try_coerce_unsized`.
1031 ///
1032 /// See: https://doc.rust-lang.org/nightly/std/marker/trait.Unsize.html
1033 fn check_unsize_and_coerce(&mut self, from_ty: &Ty, to_ty: &Ty, depth: usize) -> Option<bool> {
1034 if depth > 1000 {
1035 panic!("Infinite recursion in coercion");
1036 }
1037
1038 match (&from_ty, &to_ty) {
1039 // `[T; N]` -> `[T]`
1040 (ty_app!(TypeCtor::Array, st1), ty_app!(TypeCtor::Slice, st2)) => {
1041 Some(self.unify(&st1[0], &st2[0]))
1042 }
1043
1044 // `T` -> `dyn Trait` when `T: Trait`
1045 (_, Ty::Dyn(_)) => {
1046 // FIXME: Check predicates
1047 Some(true)
1048 }
1049
1050 // `(..., T)` -> `(..., U)` when `T: Unsize<U>`
1051 (
1052 ty_app!(TypeCtor::Tuple { cardinality: len1 }, st1),
1053 ty_app!(TypeCtor::Tuple { cardinality: len2 }, st2),
1054 ) => {
1055 if len1 != len2 || *len1 == 0 {
1056 return None;
1057 }
1058
1059 match self.check_unsize_and_coerce(
1060 st1.last().unwrap(),
1061 st2.last().unwrap(),
1062 depth + 1,
1063 ) {
1064 Some(true) => {}
1065 ret => return ret,
1066 }
1067
1068 let ret = st1[..st1.len() - 1]
1069 .iter()
1070 .zip(&st2[..st2.len() - 1])
1071 .all(|(ty1, ty2)| self.unify(ty1, ty2));
1072
1073 Some(ret)
1074 }
1075
1076 // Foo<..., T, ...> is Unsize<Foo<..., U, ...>> if:
1077 // - T: Unsize<U>
1078 // - Foo is a struct
1079 // - Only the last field of Foo has a type involving T
1080 // - T is not part of the type of any other fields
1081 // - Bar<T>: Unsize<Bar<U>>, if the last field of Foo has type Bar<T>
1082 (
1083 ty_app!(TypeCtor::Adt(Adt::Struct(struct1)), st1),
1084 ty_app!(TypeCtor::Adt(Adt::Struct(struct2)), st2),
1085 ) if struct1 == struct2 => {
1086 let fields = struct1.fields(self.db);
1087 let (last_field, prev_fields) = fields.split_last()?;
1088
1089 // Get the generic parameter involved in the last field.
1090 let unsize_generic_index = {
1091 let mut index = None;
1092 let mut multiple_param = false;
1093 last_field.ty(self.db).walk(&mut |ty| match ty {
1094 &Ty::Param { idx, .. } => {
1095 if index.is_none() {
1096 index = Some(idx);
1097 } else if Some(idx) != index {
1098 multiple_param = true;
1099 }
1100 }
1101 _ => {}
1102 });
1103
1104 if multiple_param {
1105 return None;
1106 }
1107 index?
1108 };
1109
1110 // Check other fields do not involve it.
1111 let mut multiple_used = false;
1112 prev_fields.iter().for_each(|field| {
1113 field.ty(self.db).walk(&mut |ty| match ty {
1114 &Ty::Param { idx, .. } if idx == unsize_generic_index => {
1115 multiple_used = true
1116 }
1117 _ => {}
1118 })
1119 });
1120 if multiple_used {
1121 return None;
1122 }
1123
1124 let unsize_generic_index = unsize_generic_index as usize;
1125
1126 // Check `Unsize` first
1127 match self.check_unsize_and_coerce(
1128 st1.get(unsize_generic_index)?,
1129 st2.get(unsize_generic_index)?,
1130 depth + 1,
1131 ) {
1132 Some(true) => {}
1133 ret => return ret,
1134 }
1135
1136 // Then unify other parameters
1137 let ret = st1
1138 .iter()
1139 .zip(st2.iter())
1140 .enumerate()
1141 .filter(|&(idx, _)| idx != unsize_generic_index)
1142 .all(|(_, (ty1, ty2))| self.unify(ty1, ty2));
1143
1144 Some(ret)
1145 }
1146
1147 _ => None,
1148 }
1149 }
1150
1151 /// Unify `from_ty` to `to_ty` with optional auto Deref
1152 ///
1153 /// Note that the parameters are already stripped the outer reference.
1154 fn unify_autoderef_behind_ref(&mut self, from_ty: &Ty, to_ty: &Ty) -> bool {
1155 let canonicalized = self.canonicalizer().canonicalize_ty(from_ty.clone());
1156 let to_ty = self.resolve_ty_shallow(&to_ty);
1157 // FIXME: Auto DerefMut
1158 for derefed_ty in
1159 autoderef::autoderef(self.db, &self.resolver.clone(), canonicalized.value.clone())
1160 {
1161 let derefed_ty = canonicalized.decanonicalize_ty(derefed_ty.value);
1162 match (&*self.resolve_ty_shallow(&derefed_ty), &*to_ty) {
1163 // Stop when constructor matches.
1164 (ty_app!(from_ctor, st1), ty_app!(to_ctor, st2)) if from_ctor == to_ctor => {
1165 // It will not recurse to `coerce`.
1166 return self.unify_substs(st1, st2, 0);
1167 }
1168 _ => {}
1169 }
1170 }
1171
1172 false
1173 }
1174
1175 fn infer_expr(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
1176 let ty = self.infer_expr_inner(tgt_expr, expected);
1177 let could_unify = self.unify(&ty, &expected.ty);
1178 if !could_unify {
1179 self.result.type_mismatches.insert(
1180 tgt_expr,
1181 TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() },
1182 );
1183 }
1184 let ty = self.resolve_ty_as_possible(&mut vec![], ty);
1185 ty
1186 }
1187
1188 fn infer_expr_inner(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
1189 let body = Arc::clone(&self.body); // avoid borrow checker problem
1190 let ty = match &body[tgt_expr] {
1191 Expr::Missing => Ty::Unknown,
1192 Expr::If { condition, then_branch, else_branch } => {
1193 // if let is desugared to match, so this is always simple if
1194 self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool)));
1195
1196 let then_ty = self.infer_expr_inner(*then_branch, &expected);
1197 let else_ty = match else_branch {
1198 Some(else_branch) => self.infer_expr_inner(*else_branch, &expected),
1199 None => Ty::unit(),
1200 };
1201
1202 self.coerce_merge_branch(&then_ty, &else_ty)
1203 }
1204 Expr::Block { statements, tail } => self.infer_block(statements, *tail, expected),
1205 Expr::TryBlock { body } => {
1206 let _inner = self.infer_expr(*body, expected);
1207 // FIXME should be std::result::Result<{inner}, _>
1208 Ty::Unknown
1209 }
1210 Expr::Loop { body } => {
1211 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
1212 // FIXME handle break with value
1213 Ty::simple(TypeCtor::Never)
1214 }
1215 Expr::While { condition, body } => {
1216 // while let is desugared to a match loop, so this is always simple while
1217 self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool)));
1218 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
1219 Ty::unit()
1220 }
1221 Expr::For { iterable, body, pat } => {
1222 let iterable_ty = self.infer_expr(*iterable, &Expectation::none());
1223
1224 let pat_ty = match self.resolve_into_iter_item() {
1225 Some(into_iter_item_alias) => {
1226 let pat_ty = self.new_type_var();
1227 let projection = ProjectionPredicate {
1228 ty: pat_ty.clone(),
1229 projection_ty: ProjectionTy {
1230 associated_ty: into_iter_item_alias,
1231 parameters: Substs::single(iterable_ty),
1232 },
1233 };
1234 self.obligations.push(Obligation::Projection(projection));
1235 self.resolve_ty_as_possible(&mut vec![], pat_ty)
1236 }
1237 None => Ty::Unknown,
1238 };
1239
1240 self.infer_pat(*pat, &pat_ty, BindingMode::default());
1241 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
1242 Ty::unit()
1243 }
1244 Expr::Lambda { body, args, arg_types } => {
1245 assert_eq!(args.len(), arg_types.len());
1246
1247 let mut sig_tys = Vec::new();
1248
1249 for (arg_pat, arg_type) in args.iter().zip(arg_types.iter()) {
1250 let expected = if let Some(type_ref) = arg_type {
1251 self.make_ty(type_ref)
1252 } else {
1253 Ty::Unknown
1254 };
1255 let arg_ty = self.infer_pat(*arg_pat, &expected, BindingMode::default());
1256 sig_tys.push(arg_ty);
1257 }
1258
1259 // add return type
1260 let ret_ty = self.new_type_var();
1261 sig_tys.push(ret_ty.clone());
1262 let sig_ty = Ty::apply(
1263 TypeCtor::FnPtr { num_args: sig_tys.len() as u16 - 1 },
1264 Substs(sig_tys.into()),
1265 );
1266 let closure_ty = Ty::apply_one(
1267 TypeCtor::Closure { def: self.body.owner(), expr: tgt_expr },
1268 sig_ty,
1269 );
1270
1271 // Eagerly try to relate the closure type with the expected
1272 // type, otherwise we often won't have enough information to
1273 // infer the body.
1274 self.coerce(&closure_ty, &expected.ty);
1275
1276 self.infer_expr(*body, &Expectation::has_type(ret_ty));
1277 closure_ty
1278 }
1279 Expr::Call { callee, args } => {
1280 let callee_ty = self.infer_expr(*callee, &Expectation::none());
1281 let (param_tys, ret_ty) = match callee_ty.callable_sig(self.db) {
1282 Some(sig) => (sig.params().to_vec(), sig.ret().clone()),
1283 None => {
1284 // Not callable
1285 // FIXME: report an error
1286 (Vec::new(), Ty::Unknown)
1287 }
1288 };
1289 self.register_obligations_for_call(&callee_ty);
1290 self.check_call_arguments(args, &param_tys);
1291 let ret_ty = self.normalize_associated_types_in(ret_ty);
1292 ret_ty
1293 }
1294 Expr::MethodCall { receiver, args, method_name, generic_args } => self
1295 .infer_method_call(tgt_expr, *receiver, &args, &method_name, generic_args.as_ref()),
1296 Expr::Match { expr, arms } => {
1297 let input_ty = self.infer_expr(*expr, &Expectation::none());
1298
1299 let mut result_ty = self.new_maybe_never_type_var();
1300
1301 for arm in arms {
1302 for &pat in &arm.pats {
1303 let _pat_ty = self.infer_pat(pat, &input_ty, BindingMode::default());
1304 }
1305 if let Some(guard_expr) = arm.guard {
1306 self.infer_expr(
1307 guard_expr,
1308 &Expectation::has_type(Ty::simple(TypeCtor::Bool)),
1309 );
1310 }
1311
1312 let arm_ty = self.infer_expr_inner(arm.expr, &expected);
1313 result_ty = self.coerce_merge_branch(&result_ty, &arm_ty);
1314 }
1315
1316 result_ty
1317 }
1318 Expr::Path(p) => {
1319 // FIXME this could be more efficient...
1320 let resolver = expr::resolver_for_expr(self.body.clone(), self.db, tgt_expr);
1321 self.infer_path(&resolver, p, tgt_expr.into()).unwrap_or(Ty::Unknown)
1322 }
1323 Expr::Continue => Ty::simple(TypeCtor::Never),
1324 Expr::Break { expr } => {
1325 if let Some(expr) = expr {
1326 // FIXME handle break with value
1327 self.infer_expr(*expr, &Expectation::none());
1328 }
1329 Ty::simple(TypeCtor::Never)
1330 }
1331 Expr::Return { expr } => {
1332 if let Some(expr) = expr {
1333 self.infer_expr(*expr, &Expectation::has_type(self.return_ty.clone()));
1334 }
1335 Ty::simple(TypeCtor::Never)
1336 }
1337 Expr::RecordLit { path, fields, spread } => {
1338 let (ty, def_id) = self.resolve_variant(path.as_ref());
1339 if let Some(variant) = def_id {
1340 self.write_variant_resolution(tgt_expr.into(), variant);
1341 }
1342
1343 self.unify(&ty, &expected.ty);
1344
1345 let substs = ty.substs().unwrap_or_else(Substs::empty);
1346 for (field_idx, field) in fields.iter().enumerate() {
1347 let field_ty = def_id
1348 .and_then(|it| match it.field(self.db, &field.name) {
1349 Some(field) => Some(field),
1350 None => {
1351 self.push_diagnostic(InferenceDiagnostic::NoSuchField {
1352 expr: tgt_expr,
1353 field: field_idx,
1354 });
1355 None
1356 }
1357 })
1358 .map_or(Ty::Unknown, |field| field.ty(self.db))
1359 .subst(&substs);
1360 self.infer_expr_coerce(field.expr, &Expectation::has_type(field_ty));
1361 }
1362 if let Some(expr) = spread {
1363 self.infer_expr(*expr, &Expectation::has_type(ty.clone()));
1364 }
1365 ty
1366 }
1367 Expr::Field { expr, name } => {
1368 let receiver_ty = self.infer_expr(*expr, &Expectation::none());
1369 let canonicalized = self.canonicalizer().canonicalize_ty(receiver_ty);
1370 let ty = autoderef::autoderef(
1371 self.db,
1372 &self.resolver.clone(),
1373 canonicalized.value.clone(),
1374 )
1375 .find_map(|derefed_ty| match canonicalized.decanonicalize_ty(derefed_ty.value) {
1376 Ty::Apply(a_ty) => match a_ty.ctor {
1377 TypeCtor::Tuple { .. } => name
1378 .as_tuple_index()
1379 .and_then(|idx| a_ty.parameters.0.get(idx).cloned()),
1380 TypeCtor::Adt(Adt::Struct(s)) => s.field(self.db, name).map(|field| {
1381 self.write_field_resolution(tgt_expr, field);
1382 field.ty(self.db).subst(&a_ty.parameters)
1383 }),
1384 _ => None,
1385 },
1386 _ => None,
1387 })
1388 .unwrap_or(Ty::Unknown);
1389 let ty = self.insert_type_vars(ty);
1390 self.normalize_associated_types_in(ty)
1391 }
1392 Expr::Await { expr } => {
1393 let inner_ty = self.infer_expr(*expr, &Expectation::none());
1394 let ty = match self.resolve_future_future_output() {
1395 Some(future_future_output_alias) => {
1396 let ty = self.new_type_var();
1397 let projection = ProjectionPredicate {
1398 ty: ty.clone(),
1399 projection_ty: ProjectionTy {
1400 associated_ty: future_future_output_alias,
1401 parameters: Substs::single(inner_ty),
1402 },
1403 };
1404 self.obligations.push(Obligation::Projection(projection));
1405 self.resolve_ty_as_possible(&mut vec![], ty)
1406 }
1407 None => Ty::Unknown,
1408 };
1409 ty
1410 }
1411 Expr::Try { expr } => {
1412 let inner_ty = self.infer_expr(*expr, &Expectation::none());
1413 let ty = match self.resolve_ops_try_ok() {
1414 Some(ops_try_ok_alias) => {
1415 let ty = self.new_type_var();
1416 let projection = ProjectionPredicate {
1417 ty: ty.clone(),
1418 projection_ty: ProjectionTy {
1419 associated_ty: ops_try_ok_alias,
1420 parameters: Substs::single(inner_ty),
1421 },
1422 };
1423 self.obligations.push(Obligation::Projection(projection));
1424 self.resolve_ty_as_possible(&mut vec![], ty)
1425 }
1426 None => Ty::Unknown,
1427 };
1428 ty
1429 }
1430 Expr::Cast { expr, type_ref } => {
1431 let _inner_ty = self.infer_expr(*expr, &Expectation::none());
1432 let cast_ty = self.make_ty(type_ref);
1433 // FIXME check the cast...
1434 cast_ty
1435 }
1436 Expr::Ref { expr, mutability } => {
1437 let expectation =
1438 if let Some((exp_inner, exp_mutability)) = &expected.ty.as_reference() {
1439 if *exp_mutability == Mutability::Mut && *mutability == Mutability::Shared {
1440 // FIXME: throw type error - expected mut reference but found shared ref,
1441 // which cannot be coerced
1442 }
1443 Expectation::has_type(Ty::clone(exp_inner))
1444 } else {
1445 Expectation::none()
1446 };
1447 // FIXME reference coercions etc.
1448 let inner_ty = self.infer_expr(*expr, &expectation);
1449 Ty::apply_one(TypeCtor::Ref(*mutability), inner_ty)
1450 }
1451 Expr::Box { expr } => {
1452 let inner_ty = self.infer_expr(*expr, &Expectation::none());
1453 if let Some(box_) = self.resolve_boxed_box() {
1454 Ty::apply_one(TypeCtor::Adt(box_), inner_ty)
1455 } else {
1456 Ty::Unknown
1457 }
1458 }
1459 Expr::UnaryOp { expr, op } => {
1460 let inner_ty = self.infer_expr(*expr, &Expectation::none());
1461 match op {
1462 UnaryOp::Deref => {
1463 let canonicalized = self.canonicalizer().canonicalize_ty(inner_ty);
1464 if let Some(derefed_ty) =
1465 autoderef::deref(self.db, &self.resolver, &canonicalized.value)
1466 {
1467 canonicalized.decanonicalize_ty(derefed_ty.value)
1468 } else {
1469 Ty::Unknown
1470 }
1471 }
1472 UnaryOp::Neg => {
1473 match &inner_ty {
1474 Ty::Apply(a_ty) => match a_ty.ctor {
1475 TypeCtor::Int(primitive::UncertainIntTy::Unknown)
1476 | TypeCtor::Int(primitive::UncertainIntTy::Known(
1477 primitive::IntTy {
1478 signedness: primitive::Signedness::Signed,
1479 ..
1480 },
1481 ))
1482 | TypeCtor::Float(..) => inner_ty,
1483 _ => Ty::Unknown,
1484 },
1485 Ty::Infer(InferTy::IntVar(..)) | Ty::Infer(InferTy::FloatVar(..)) => {
1486 inner_ty
1487 }
1488 // FIXME: resolve ops::Neg trait
1489 _ => Ty::Unknown,
1490 }
1491 }
1492 UnaryOp::Not => {
1493 match &inner_ty {
1494 Ty::Apply(a_ty) => match a_ty.ctor {
1495 TypeCtor::Bool | TypeCtor::Int(_) => inner_ty,
1496 _ => Ty::Unknown,
1497 },
1498 Ty::Infer(InferTy::IntVar(..)) => inner_ty,
1499 // FIXME: resolve ops::Not trait for inner_ty
1500 _ => Ty::Unknown,
1501 }
1502 }
1503 }
1504 }
1505 Expr::BinaryOp { lhs, rhs, op } => match op {
1506 Some(op) => {
1507 let lhs_expectation = match op {
1508 BinaryOp::LogicOp(..) => Expectation::has_type(Ty::simple(TypeCtor::Bool)),
1509 _ => Expectation::none(),
1510 };
1511 let lhs_ty = self.infer_expr(*lhs, &lhs_expectation);
1512 // FIXME: find implementation of trait corresponding to operation
1513 // symbol and resolve associated `Output` type
1514 let rhs_expectation = op::binary_op_rhs_expectation(*op, lhs_ty);
1515 let rhs_ty = self.infer_expr(*rhs, &Expectation::has_type(rhs_expectation));
1516
1517 // FIXME: similar as above, return ty is often associated trait type
1518 op::binary_op_return_ty(*op, rhs_ty)
1519 }
1520 _ => Ty::Unknown,
1521 },
1522 Expr::Index { base, index } => {
1523 let _base_ty = self.infer_expr(*base, &Expectation::none());
1524 let _index_ty = self.infer_expr(*index, &Expectation::none());
1525 // FIXME: use `std::ops::Index::Output` to figure out the real return type
1526 Ty::Unknown
1527 }
1528 Expr::Tuple { exprs } => {
1529 let mut tys = match &expected.ty {
1530 ty_app!(TypeCtor::Tuple { .. }, st) => st
1531 .iter()
1532 .cloned()
1533 .chain(repeat_with(|| self.new_type_var()))
1534 .take(exprs.len())
1535 .collect::<Vec<_>>(),
1536 _ => (0..exprs.len()).map(|_| self.new_type_var()).collect(),
1537 };
1538
1539 for (expr, ty) in exprs.iter().zip(tys.iter_mut()) {
1540 self.infer_expr_coerce(*expr, &Expectation::has_type(ty.clone()));
1541 }
1542
1543 Ty::apply(TypeCtor::Tuple { cardinality: tys.len() as u16 }, Substs(tys.into()))
1544 }
1545 Expr::Array(array) => {
1546 let elem_ty = match &expected.ty {
1547 ty_app!(TypeCtor::Array, st) | ty_app!(TypeCtor::Slice, st) => {
1548 st.as_single().clone()
1549 }
1550 _ => self.new_type_var(),
1551 };
1552
1553 match array {
1554 Array::ElementList(items) => {
1555 for expr in items.iter() {
1556 self.infer_expr_coerce(*expr, &Expectation::has_type(elem_ty.clone()));
1557 }
1558 }
1559 Array::Repeat { initializer, repeat } => {
1560 self.infer_expr_coerce(
1561 *initializer,
1562 &Expectation::has_type(elem_ty.clone()),
1563 );
1564 self.infer_expr(
1565 *repeat,
1566 &Expectation::has_type(Ty::simple(TypeCtor::Int(
1567 primitive::UncertainIntTy::Known(primitive::IntTy::usize()),
1568 ))),
1569 );
1570 }
1571 }
1572
1573 Ty::apply_one(TypeCtor::Array, elem_ty)
1574 }
1575 Expr::Literal(lit) => match lit {
1576 Literal::Bool(..) => Ty::simple(TypeCtor::Bool),
1577 Literal::String(..) => {
1578 Ty::apply_one(TypeCtor::Ref(Mutability::Shared), Ty::simple(TypeCtor::Str))
1579 }
1580 Literal::ByteString(..) => {
1581 let byte_type = Ty::simple(TypeCtor::Int(primitive::UncertainIntTy::Known(
1582 primitive::IntTy::u8(),
1583 )));
1584 let slice_type = Ty::apply_one(TypeCtor::Slice, byte_type);
1585 Ty::apply_one(TypeCtor::Ref(Mutability::Shared), slice_type)
1586 }
1587 Literal::Char(..) => Ty::simple(TypeCtor::Char),
1588 Literal::Int(_v, ty) => Ty::simple(TypeCtor::Int(*ty)),
1589 Literal::Float(_v, ty) => Ty::simple(TypeCtor::Float(*ty)),
1590 },
1591 };
1592 // use a new type variable if we got Ty::Unknown here
1593 let ty = self.insert_type_vars_shallow(ty);
1594 let ty = self.resolve_ty_as_possible(&mut vec![], ty);
1595 self.write_expr_ty(tgt_expr, ty.clone());
1596 ty
1597 }
1598
1599 fn infer_block(
1600 &mut self,
1601 statements: &[Statement],
1602 tail: Option<ExprId>,
1603 expected: &Expectation,
1604 ) -> Ty {
1605 let mut diverges = false;
1606 for stmt in statements {
1607 match stmt {
1608 Statement::Let { pat, type_ref, initializer } => {
1609 let decl_ty =
1610 type_ref.as_ref().map(|tr| self.make_ty(tr)).unwrap_or(Ty::Unknown);
1611
1612 // Always use the declared type when specified
1613 let mut ty = decl_ty.clone();
1614
1615 if let Some(expr) = initializer {
1616 let actual_ty =
1617 self.infer_expr_coerce(*expr, &Expectation::has_type(decl_ty.clone()));
1618 if decl_ty == Ty::Unknown {
1619 ty = actual_ty;
1620 }
1621 }
1622
1623 let ty = self.resolve_ty_as_possible(&mut vec![], ty);
1624 self.infer_pat(*pat, &ty, BindingMode::default());
1625 }
1626 Statement::Expr(expr) => {
1627 if let ty_app!(TypeCtor::Never) = self.infer_expr(*expr, &Expectation::none()) {
1628 diverges = true;
1629 }
1630 }
1631 }
1632 }
1633
1634 let ty = if let Some(expr) = tail {
1635 self.infer_expr_coerce(expr, expected)
1636 } else {
1637 self.coerce(&Ty::unit(), &expected.ty);
1638 Ty::unit()
1639 };
1640 if diverges {
1641 Ty::simple(TypeCtor::Never)
1642 } else {
1643 ty
1644 }
1645 }
1646
1647 fn check_call_arguments(&mut self, args: &[ExprId], param_tys: &[Ty]) {
1648 // Quoting https://github.com/rust-lang/rust/blob/6ef275e6c3cb1384ec78128eceeb4963ff788dca/src/librustc_typeck/check/mod.rs#L3325 --
1649 // We do this in a pretty awful way: first we type-check any arguments
1650 // that are not closures, then we type-check the closures. This is so
1651 // that we have more information about the types of arguments when we
1652 // type-check the functions. This isn't really the right way to do this.
1653 for &check_closures in &[false, true] {
1654 let param_iter = param_tys.iter().cloned().chain(repeat(Ty::Unknown));
1655 for (&arg, param_ty) in args.iter().zip(param_iter) {
1656 let is_closure = match &self.body[arg] {
1657 Expr::Lambda { .. } => true,
1658 _ => false,
1659 };
1660
1661 if is_closure != check_closures {
1662 continue;
1663 }
1664
1665 let param_ty = self.normalize_associated_types_in(param_ty);
1666 self.infer_expr_coerce(arg, &Expectation::has_type(param_ty.clone()));
1667 }
1668 }
1669 }
1670
1671 fn collect_const(&mut self, data: &ConstData) { 559 fn collect_const(&mut self, data: &ConstData) {
1672 self.return_ty = self.make_ty(data.type_ref()); 560 self.return_ty = self.make_ty(data.type_ref());
1673 } 561 }
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-03 18:04:03 +0100