Rollup merge of #113187 - compiler-errors:local-ty, r=b-naber

No need to distinguish `LocalTy` from `Ty`

I think the distinction between `decl_ty` and `revealed_ty` was from when you were allowed to put `impl Trait` in let bindings... I don't think we need that anymore, and it makes typeck that much more confusing 😆

Side-note: I don't know why we store this in a separate field [`locals`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_hir_typeck/struct.Inherited.html#structfield.locals) in `Inherited`, rather than just the `TypeckResults`... Might look into changing that next.

Author: matthiaskrgr

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -2,7 +2,7 @@ use crate::callee::{self, DeferredCallResolution};
 use crate::errors::CtorIsPrivate;
 use crate::method::{self, MethodCallee, SelfSource};
 use crate::rvalue_scopes;
-use crate::{BreakableCtxt, Diverges, Expectation, FnCtxt, LocalTy, RawTy};
+use crate::{BreakableCtxt, Diverges, Expectation, FnCtxt, RawTy};
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{Applicability, Diagnostic, ErrorGuaranteed, MultiSpan, StashKey};
@@ -135,7 +135,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         format!("{:p}", self)
     }
 
-    pub fn local_ty(&self, span: Span, nid: hir::HirId) -> LocalTy<'tcx> {
+    pub fn local_ty(&self, span: Span, nid: hir::HirId) -> Ty<'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))
         })
@@ -1152,7 +1152,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         );
 
         if let Res::Local(hid) = res {
-            let ty = self.local_ty(span, hid).decl_ty;
+            let ty = self.local_ty(span, hid);
             let ty = self.normalize(span, ty);
             self.write_ty(hir_id, ty);
             return (ty, res);

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -6,8 +6,7 @@ use crate::method::MethodCallee;
 use crate::TupleArgumentsFlag::*;
 use crate::{errors, Expectation::*};
 use crate::{
-    struct_span_err, BreakableCtxt, Diverges, Expectation, FnCtxt, LocalTy, Needs, RawTy,
-    TupleArgumentsFlag,
+    struct_span_err, BreakableCtxt, Diverges, Expectation, FnCtxt, Needs, RawTy, TupleArgumentsFlag,
 };
 use rustc_ast as ast;
 use rustc_data_structures::fx::FxIndexSet;
@@ -1423,7 +1422,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // See #44848.
         let ref_bindings = pat.contains_explicit_ref_binding();
 
-        let local_ty = self.local_ty(init.span, hir_id).revealed_ty;
+        let local_ty = self.local_ty(init.span, hir_id);
         if let Some(m) = ref_bindings {
             // Somewhat subtle: if we have a `ref` binding in the pattern,
             // we want to avoid introducing coercions for the RHS. This is
@@ -1453,7 +1452,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
     pub(in super::super) fn check_decl(&self, decl: Declaration<'tcx>) {
         // Determine and write the type which we'll check the pattern against.
-        let decl_ty = self.local_ty(decl.span, decl.hir_id).decl_ty;
+        let decl_ty = self.local_ty(decl.span, decl.hir_id);
         self.write_ty(decl.hir_id, decl_ty);
 
         // Type check the initializer.
@@ -1799,9 +1798,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             let err = self.tcx.ty_error(guar);
             self.write_ty(hir_id, err);
             self.write_ty(pat.hir_id, err);
-            let local_ty = LocalTy { decl_ty: err, revealed_ty: err };
-            self.locals.borrow_mut().insert(hir_id, local_ty);
-            self.locals.borrow_mut().insert(pat.hir_id, local_ty);
+            self.locals.borrow_mut().insert(hir_id, err);
+            self.locals.borrow_mut().insert(pat.hir_id, err);
         }
     }
 

compiler/rustc_hir_typeck/src/gather_locals.rs

@@ -1,4 +1,4 @@
-use crate::{FnCtxt, LocalTy};
+use crate::FnCtxt;
 use rustc_hir as hir;
 use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::PatKind;
@@ -48,31 +48,28 @@ impl<'a, 'tcx> GatherLocalsVisitor<'a, 'tcx> {
         Self { fcx, outermost_fn_param_pat: None }
     }
 
-    fn assign(&mut self, span: Span, nid: hir::HirId, ty_opt: Option<LocalTy<'tcx>>) -> Ty<'tcx> {
+    fn assign(&mut self, span: Span, nid: hir::HirId, ty_opt: Option<Ty<'tcx>>) -> Ty<'tcx> {
         match ty_opt {
             None => {
                 // Infer the variable's type.
                 let var_ty = self.fcx.next_ty_var(TypeVariableOrigin {
                     kind: TypeVariableOriginKind::TypeInference,
                     span,
                 });
-                self.fcx
-                    .locals
-                    .borrow_mut()
-                    .insert(nid, LocalTy { decl_ty: var_ty, revealed_ty: var_ty });
+                self.fcx.locals.borrow_mut().insert(nid, var_ty);
                 var_ty
             }
             Some(typ) => {
                 // Take type that the user specified.
                 self.fcx.locals.borrow_mut().insert(nid, typ);
-                typ.revealed_ty
+                typ
             }
         }
     }
 
-    /// Allocates a [LocalTy] for a declaration, which may have a type annotation. If it does have
-    /// a type annotation, then the LocalTy stored will be the resolved type. This may be found
-    /// again during type checking by querying [FnCtxt::local_ty] for the same hir_id.
+    /// Allocates a type for a declaration, which may have a type annotation. If it does have
+    /// a type annotation, then the [`Ty`] stored will be the resolved type. This may be found
+    /// again during type checking by querying [`FnCtxt::local_ty`] for the same hir_id.
     fn declare(&mut self, decl: Declaration<'tcx>) {
         let local_ty = match decl.ty {
             Some(ref ty) => {
@@ -87,7 +84,7 @@ impl<'a, 'tcx> GatherLocalsVisitor<'a, 'tcx> {
                     .user_provided_types_mut()
                     .insert(ty.hir_id, c_ty);
 
-                Some(LocalTy { decl_ty: o_ty.normalized, revealed_ty: o_ty.normalized })
+                Some(o_ty.normalized)
             }
             None => None,
         };
@@ -96,7 +93,7 @@ impl<'a, 'tcx> GatherLocalsVisitor<'a, 'tcx> {
         debug!(
             "local variable {:?} is assigned type {}",
             decl.pat,
-            self.fcx.ty_to_string(self.fcx.locals.borrow().get(&decl.hir_id).unwrap().decl_ty)
+            self.fcx.ty_to_string(*self.fcx.locals.borrow().get(&decl.hir_id).unwrap())
         );
     }
 }
@@ -151,7 +148,7 @@ impl<'a, 'tcx> Visitor<'tcx> for GatherLocalsVisitor<'a, 'tcx> {
             debug!(
                 "pattern binding {} is assigned to {} with type {:?}",
                 ident,
-                self.fcx.ty_to_string(self.fcx.locals.borrow().get(&p.hir_id).unwrap().decl_ty),
+                self.fcx.ty_to_string(*self.fcx.locals.borrow().get(&p.hir_id).unwrap()),
                 var_ty
             );
         }

compiler/rustc_hir_typeck/src/inherited.rs

@@ -30,7 +30,7 @@ pub struct Inherited<'tcx> {
 
     pub(super) typeck_results: RefCell<ty::TypeckResults<'tcx>>,
 
-    pub(super) locals: RefCell<HirIdMap<super::LocalTy<'tcx>>>,
+    pub(super) locals: RefCell<HirIdMap<Ty<'tcx>>>,
 
     pub(super) fulfillment_cx: RefCell<Box<dyn TraitEngine<'tcx>>>,
 

compiler/rustc_hir_typeck/src/lib.rs

@@ -89,13 +89,6 @@ macro_rules! type_error_struct {
     })
 }
 
-/// The type of a local binding, including the revealed type for anon types.
-#[derive(Copy, Clone, Debug)]
-pub struct LocalTy<'tcx> {
-    decl_ty: Ty<'tcx>,
-    revealed_ty: Ty<'tcx>,
-}
-
 /// If this `DefId` is a "primary tables entry", returns
 /// `Some((body_id, body_ty, fn_sig))`. Otherwise, returns `None`.
 ///

compiler/rustc_hir_typeck/src/pat.rs

@@ -594,7 +594,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         debug!("check_pat_ident: pat.hir_id={:?} bm={:?}", pat.hir_id, bm);
 
-        let local_ty = self.local_ty(pat.span, pat.hir_id).decl_ty;
+        let local_ty = self.local_ty(pat.span, pat.hir_id);
         let eq_ty = match bm {
             ty::BindByReference(mutbl) => {
                 // If the binding is like `ref x | ref mut x`,
@@ -635,7 +635,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         ty: Ty<'tcx>,
         ti: TopInfo<'tcx>,
     ) {
-        let var_ty = self.local_ty(span, var_id).decl_ty;
+        let var_ty = self.local_ty(span, var_id);
         if let Some(mut err) = self.demand_eqtype_pat_diag(span, var_ty, ty, ti) {
             let hir = self.tcx.hir();
             let var_ty = self.resolve_vars_with_obligations(var_ty);

compiler/rustc_hir_typeck/src/writeback.rs

@@ -348,7 +348,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
 
     fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
         intravisit::walk_local(self, l);
-        let var_ty = self.fcx.local_ty(l.span, l.hir_id).decl_ty;
+        let var_ty = self.fcx.local_ty(l.span, l.hir_id);
         let var_ty = self.resolve(var_ty, &l.span);
         self.write_ty_to_typeck_results(l.hir_id, var_ty);
     }