Rollup merge of #130033 - compiler-errors:foreign-fn-types, r=BoxyUwU

Don't call `fn_arg_names` query for non-`fn` foreign items in resolver

Fixes #130015

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -2068,11 +2068,14 @@ fn extract_node_id(t: &Ty) -> Option<NodeId> {
             ) {
                 let res = binding.res();
                 if filter_fn(res) {
-                    let def_id = res.def_id();
+                    match res {
+                        Res::Def(DefKind::Fn | DefKind::AssocFn, def_id) => {
                             let has_self = match def_id.as_local() {
-                        Some(def_id) => {
+                                Some(def_id) => self
-                            self.r.delegation_fn_sigs.get(&def_id).map_or(false, |sig| sig.has_self)
+                                    .r
-                        }
+                                    .delegation_fn_sigs
+                                    .get(&def_id)
+                                    .map_or(false, |sig| sig.has_self),
                                 None => self
                                     .r
                                     .tcx
@@ -2083,10 +2086,9 @@ fn extract_node_id(t: &Ty) -> Option<NodeId> {
                             if has_self {
                                 return Some(AssocSuggestion::MethodWithSelf { called });
                             } else {
-                        match res {
-                            Res::Def(DefKind::AssocFn, _) => {
                                 return Some(AssocSuggestion::AssocFn { called });
                             }
+                        }
                         Res::Def(DefKind::AssocConst, _) => {
                             return Some(AssocSuggestion::AssocConst);
                         }
@@ -2098,7 +2100,6 @@ fn extract_node_id(t: &Ty) -> Option<NodeId> {
                 }
             }
         }
-        }
 
         None
     }

tests/ui/resolve/auxiliary/foreign-trait-with-assoc.rs

@@ -0,0 +1,3 @@
+pub trait Foo {
+    type Bar;
+}

tests/ui/resolve/dont-compute-arg-names-for-non-fn.rs

@@ -0,0 +1,11 @@
+//@ aux-build:foreign-trait-with-assoc.rs
+
+extern crate foreign_trait_with_assoc;
+use foreign_trait_with_assoc::Foo;
+
+// Make sure we don't try to call `fn_arg_names` on a non-fn item.
+
+impl Foo for Bar {}
+//~^ ERROR cannot find type `Bar` in this scope
+
+fn main() {}

tests/ui/resolve/dont-compute-arg-names-for-non-fn.stderr

@@ -0,0 +1,14 @@
+error[E0412]: cannot find type `Bar` in this scope
+  --> $DIR/dont-compute-arg-names-for-non-fn.rs:8:14
+   |
+LL | impl Foo for Bar {}
+   |              ^^^
+   |
+help: you might have meant to use the associated type
+   |
+LL | impl Foo for Self::Bar {}
+   |              ++++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0412`.