Rollup merge of rust-lang#71087 - JohnTitor:impl-self-ty, r=eddyb

Remove `FnCtxt::impl_self_ty`

Fixes rust-lang#69489
r? @eddyb cc @Centril

Author: Dylan-DPC

src/librustc_typeck/check/method/confirm.rs

@@ -209,7 +209,7 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
                     "impl {:?} is not an inherent impl",
                     impl_def_id
                 );
-                self.impl_self_ty(self.span, impl_def_id).substs
+                self.fresh_substs_for_item(self.span, impl_def_id)
             }
 
             probe::ObjectPick => {

src/librustc_typeck/check/method/probe.rs

@@ -1128,8 +1128,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
     ) -> Option<PickResult<'tcx>> {
         let tcx = self.tcx;
 
-        // In general, during probing we erase regions. See
-        // `impl_self_ty()` for an explanation.
+        // In general, during probing we erase regions.
         let region = tcx.lifetimes.re_erased;
 
         let autoref_ty = tcx.mk_ref(region, ty::TypeAndMut { ty: self_ty, mutbl });
@@ -1614,8 +1613,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                 } else {
                     match param.kind {
                         GenericParamDefKind::Lifetime => {
-                            // In general, during probe we erase regions. See
-                            // `impl_self_ty()` for an explanation.
+                            // In general, during probe we erase regions.
                             self.tcx.lifetimes.re_erased.into()
                         }
                         GenericParamDefKind::Type { .. } | GenericParamDefKind::Const => {

src/librustc_typeck/check/method/suggest.rs

@@ -117,7 +117,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             .span_if_local(item.def_id)
                             .or_else(|| self.tcx.hir().span_if_local(impl_did));
 
-                        let impl_ty = self.impl_self_ty(span, impl_did).ty;
+                        let impl_ty = self.tcx.at(span).type_of(impl_did);
 
                         let insertion = match self.tcx.impl_trait_ref(impl_did) {
                             None => String::new(),
@@ -537,7 +537,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         // When the "method" is resolved through dereferencing, we really want the
                         // original type that has the associated function for accurate suggestions.
                         // (#61411)
-                        let ty = self.impl_self_ty(span, *impl_did).ty;
+                        let ty = tcx.at(span).type_of(*impl_did);
                         match (&ty.peel_refs().kind, &actual.peel_refs().kind) {
                             (ty::Adt(def, _), ty::Adt(def_actual, _)) if def == def_actual => {
                                 // Use `actual` as it will have more `substs` filled in.

src/librustc_typeck/check/mod.rs

@@ -154,7 +154,6 @@ use std::slice;
 
 use crate::require_c_abi_if_c_variadic;
 use crate::util::common::indenter;
-use crate::TypeAndSubsts;
 
 use self::autoderef::Autoderef;
 use self::callee::DeferredCallResolution;
@@ -4251,24 +4250,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
-    // Determine the `Self` type, using fresh variables for all variables
-    // declared on the impl declaration e.g., `impl<A,B> for Vec<(A,B)>`
-    // would return `($0, $1)` where `$0` and `$1` are freshly instantiated type
-    // variables.
-    pub fn impl_self_ty(
-        &self,
-        span: Span, // (potential) receiver for this impl
-        did: DefId,
-    ) -> TypeAndSubsts<'tcx> {
-        let ity = self.tcx.type_of(did);
-        debug!("impl_self_ty: ity={:?}", ity);
-
-        let substs = self.fresh_substs_for_item(span, did);
-        let substd_ty = self.instantiate_type_scheme(span, &substs, &ity);
-
-        TypeAndSubsts { substs, ty: substd_ty }
-    }
-
     /// Unifies the output type with the expected type early, for more coercions
     /// and forward type information on the input expressions.
     fn expected_inputs_for_expected_output(

src/librustc_typeck/lib.rs

@@ -97,7 +97,6 @@ use rustc_infer::infer::{InferOk, TyCtxtInferExt};
 use rustc_infer::traits::TraitEngineExt as _;
 use rustc_middle::middle;
 use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::util;
 use rustc_session::config::EntryFnType;
@@ -111,10 +110,6 @@ use rustc_trait_selection::traits::{
 use std::iter;
 
 use astconv::{AstConv, Bounds};
-pub struct TypeAndSubsts<'tcx> {
-    substs: SubstsRef<'tcx>,
-    ty: Ty<'tcx>,
-}
 
 fn require_c_abi_if_c_variadic(tcx: TyCtxt<'_>, decl: &hir::FnDecl<'_>, abi: Abi, span: Span) {
     if decl.c_variadic && !(abi == Abi::C || abi == Abi::Cdecl) {

src/test/ui/issues/issue-18446.stderr

@@ -7,7 +7,7 @@ LL |     x.foo();
    |     | multiple `foo` found
    |     help: disambiguate the method call for candidate #2: `T::foo(&x)`
    |
-note: candidate #1 is defined in an impl for the type `dyn T`
+note: candidate #1 is defined in an impl for the type `(dyn T + 'a)`
   --> $DIR/issue-18446.rs:9:5
    |
 LL |     fn foo(&self) {}

src/test/ui/methods/method-deref-to-same-trait-object-with-separate-params.stderr

@@ -20,12 +20,12 @@ error[E0034]: multiple applicable items in scope
 LL |     let z = x.foo();
    |               ^^^ multiple `foo` found
    |
-note: candidate #1 is defined in an impl of the trait `internal::X` for the type `_`
+note: candidate #1 is defined in an impl of the trait `internal::X` for the type `T`
   --> $DIR/method-deref-to-same-trait-object-with-separate-params.rs:43:9
    |
 LL |         fn foo(self: Smaht<Self, u64>) -> u64 {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-note: candidate #2 is defined in an impl of the trait `nuisance_foo::NuisanceFoo` for the type `_`
+note: candidate #2 is defined in an impl of the trait `nuisance_foo::NuisanceFoo` for the type `T`
   --> $DIR/method-deref-to-same-trait-object-with-separate-params.rs:70:9
    |
 LL |         fn foo(self) {}

src/test/ui/suggestions/suggest-assoc-fn-call-with-turbofish.stderr

@@ -11,7 +11,7 @@ LL |     x.default_hello();
    |     help: use associated function syntax instead: `GenericAssocMethod::<i32>::default_hello`
    |
    = note: found the following associated functions; to be used as methods, functions must have a `self` parameter
-note: the candidate is defined in an impl for the type `GenericAssocMethod<_>`
+note: the candidate is defined in an impl for the type `GenericAssocMethod<T>`
   --> $DIR/suggest-assoc-fn-call-with-turbofish.rs:4:5
    |
 LL |     fn default_hello() {}