Also check for associated fns on primitives in E0223 similar-path check.

Author: zachs18

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

@@ -9,6 +9,7 @@ use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::DefId;
 use rustc_middle::bug;
+use rustc_middle::ty::fast_reject::{TreatParams, simplify_type};
 use rustc_middle::ty::print::{PrintPolyTraitRefExt as _, PrintTraitRefExt as _};
 use rustc_middle::ty::{
     self, AdtDef, GenericParamDefKind, Ty, TyCtxt, TypeVisitableExt,
@@ -998,10 +999,15 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                     )),
                 ..
             }) = node
-            && let Some(adt_def) = qself_ty.ty_adt_def()
+            && let Some(inherent_impls) = qself_ty
+                .ty_adt_def()
+                .map(|adt_def| tcx.inherent_impls(adt_def.did()))
+                .or_else(|| {
+                    simplify_type(tcx, qself_ty, TreatParams::InstantiateWithInfer)
+                        .map(|simple_ty| tcx.incoherent_impls(simple_ty))
+                })
             && let name = Symbol::intern(&format!("{ident2}_{ident3}"))
-            && let Some(ty::AssocItem { kind: ty::AssocKind::Fn, .. }) = tcx
-                .inherent_impls(adt_def.did())
+            && let Some(ty::AssocItem { kind: ty::AssocKind::Fn, .. }) = inherent_impls
                 .iter()
                 .flat_map(|inherent_impl| {
                     tcx.associated_items(inherent_impl).filter_by_name_unhygienic(name)

tests/ui/suggestions/issue-109195.rs

@@ -21,12 +21,12 @@ fn main() {
     String::from::method_that_doesnt_exist();
     //~^ ERROR ambiguous associated type [E0223]
     //~| HELP if there were a trait named `Example` with associated type `from`
-    str::from::utf8();
+    str::into::string();
     //~^ ERROR ambiguous associated type [E0223]
-    //~| HELP if there were a trait named `Example` with associated type `from`
-    str::from::utf8_mut();
+    //~| HELP there is an associated function with a similar name: `into_string`
+    str::char::indices();
     //~^ ERROR ambiguous associated type [E0223]
-    //~| HELP if there were a trait named `Example` with associated type `from`
+    //~| HELP there is an associated function with a similar name: `char_indices`
     Foo::bar::baz;
     //~^ ERROR ambiguous associated type [E0223]
     //~| HELP there is an associated function with a similar name: `bar_baz`
@@ -36,4 +36,15 @@ fn main() {
     Foo::bar::fizz;
     //~^ ERROR ambiguous associated type [E0223]
     //~| HELP if there were a trait named `Example` with associated type `bar`
+    i32::wrapping::add;
+    //~^ ERROR ambiguous associated type [E0223]
+    //~| HELP there is an associated function with a similar name: `wrapping_add`
+    i32::wrapping::method_that_doesnt_exist;
+    //~^ ERROR ambiguous associated type [E0223]
+    //~| HELP if there were a trait named `Example` with associated type `wrapping`
+
+    // this one ideally should suggest `downcast_mut_unchecked`
+    <dyn std::any::Any>::downcast::mut_unchecked;
+    //~^ ERROR ambiguous associated type [E0223]
+    //~| HELP if there were a trait named `Example` with associated type `downcast`
 }

tests/ui/suggestions/issue-109195.stderr

@@ -45,24 +45,24 @@ LL |     <String as Example>::from::method_that_doesnt_exist();
 error[E0223]: ambiguous associated type
   --> $DIR/issue-109195.rs:24:5
    |
-LL |     str::from::utf8();
+LL |     str::into::string();
    |     ^^^^^^^^^
    |
-help: if there were a trait named `Example` with associated type `from` implemented for `str`, you could use the fully-qualified path
+help: there is an associated function with a similar name: `into_string`
    |
-LL |     <str as Example>::from::utf8();
-   |     ~~~~~~~~~~~~~~~~~~~~~~
+LL |     str::into_string();
+   |          ~~~~~~~~~~~
 
 error[E0223]: ambiguous associated type
   --> $DIR/issue-109195.rs:27:5
    |
-LL |     str::from::utf8_mut();
+LL |     str::char::indices();
    |     ^^^^^^^^^
    |
-help: if there were a trait named `Example` with associated type `from` implemented for `str`, you could use the fully-qualified path
+help: there is an associated function with a similar name: `char_indices`
    |
-LL |     <str as Example>::from::utf8_mut();
-   |     ~~~~~~~~~~~~~~~~~~~~~~
+LL |     str::char_indices();
+   |          ~~~~~~~~~~~~
 
 error[E0223]: ambiguous associated type
   --> $DIR/issue-109195.rs:30:5
@@ -97,6 +97,39 @@ help: if there were a trait named `Example` with associated type `bar` implement
 LL |     <Foo as Example>::bar::fizz;
    |     ~~~~~~~~~~~~~~~~~~~~~
 
-error: aborting due to 9 previous errors
+error[E0223]: ambiguous associated type
+  --> $DIR/issue-109195.rs:39:5
+   |
+LL |     i32::wrapping::add;
+   |     ^^^^^^^^^^^^^
+   |
+help: there is an associated function with a similar name: `wrapping_add`
+   |
+LL |     i32::wrapping_add;
+   |          ~~~~~~~~~~~~
+
+error[E0223]: ambiguous associated type
+  --> $DIR/issue-109195.rs:42:5
+   |
+LL |     i32::wrapping::method_that_doesnt_exist;
+   |     ^^^^^^^^^^^^^
+   |
+help: if there were a trait named `Example` with associated type `wrapping` implemented for `i32`, you could use the fully-qualified path
+   |
+LL |     <i32 as Example>::wrapping::method_that_doesnt_exist;
+   |     ~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+error[E0223]: ambiguous associated type
+  --> $DIR/issue-109195.rs:47:5
+   |
+LL |     <dyn std::any::Any>::downcast::mut_unchecked;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: if there were a trait named `Example` with associated type `downcast` implemented for `(dyn Any + 'static)`, you could use the fully-qualified path
+   |
+LL |     <(dyn Any + 'static) as Example>::downcast::mut_unchecked;
+   |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+error: aborting due to 12 previous errors
 
 For more information about this error, try `rustc --explain E0223`.