Fix suggestion span for typo in associated type name

Author: estebank

src/librustc_typeck/astconv.rs

@@ -1814,7 +1814,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         assoc_name: ast::Ident,
         span: Span,
         is_equality: Option<String>,
-    ) -> Result<ty::PolyTraitRef<'tcx>, ErrorReported> 
+    ) -> Result<ty::PolyTraitRef<'tcx>, ErrorReported>
         where I: Iterator<Item = ty::PolyTraitRef<'tcx>>,
     {
         let mut matching_candidates = all_candidates().filter(|r| {
@@ -1828,7 +1828,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     all_candidates,
                     ty_param_name,
                     assoc_name,
-                    span
+                    span,
                 );
                 return Err(ErrorReported);
             }
@@ -1916,16 +1916,26 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         return Ok(bound);
     }
 
-    fn complain_about_assoc_type_not_found<I>(&self,
-                                              all_candidates: impl Fn() -> I,
-                                              ty_param_name: &str,
-                                              assoc_name: ast::Ident,
-                                              span: Span)
-    where I: Iterator<Item = ty::PolyTraitRef<'tcx>> {
-        let mut err = struct_span_err!(self.tcx().sess, span, E0220,
-                                 "associated type `{}` not found for `{}`",
-                                 assoc_name,
-                                 ty_param_name);
+    fn complain_about_assoc_type_not_found<I>(
+        &self,
+        all_candidates: impl Fn() -> I,
+        ty_param_name: &str,
+        assoc_name: ast::Ident,
+        span: Span,
+    ) where I: Iterator<Item = ty::PolyTraitRef<'tcx>> {
+        // The fallback span is needed because `assoc_name` might be an `Fn()`'s `Output` without a
+        // valid span, so we point at the whole path segment instead.
+        let span = if assoc_name.span != DUMMY_SP {
+            assoc_name.span
+        } else {
+            span
+        };
+        let mut err = struct_span_err!(
+            self.tcx().sess, span, E0220,
+            "associated type `{}` not found for `{}`",
+            assoc_name,
+            ty_param_name
+        );
 
         let all_candidate_names: Vec<_> = all_candidates()
             .map(|r| self.tcx().associated_items(r.def_id()))
@@ -1939,22 +1949,18 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             )
             .collect();
 
-        if let Some(suggested_name) = find_best_match_for_name(
-            all_candidate_names.iter(),
-            &assoc_name.as_str(),
-            None,
+        if let (Some(suggested_name), true) = (
+            find_best_match_for_name(all_candidate_names.iter(), &assoc_name.as_str(), None),
+            assoc_name.span != DUMMY_SP,
         ) {
             err.span_suggestion(
-                span,
+                assoc_name.span,
                 "there is an associated type with a similar name",
                 suggested_name.to_string(),
                 Applicability::MaybeIncorrect,
             );
         } else {
-            err.span_label(
-                span,
-                format!("associated type `{}` not found", assoc_name)
-            );
+            err.span_label(span, format!("associated type `{}` not found", assoc_name));
         }
 
         err.emit();

src/test/ui/associated-types/associated-types-path-1.stderr

@@ -1,8 +1,8 @@
 error[E0220]: associated type `A` not found for `T`
-  --> $DIR/associated-types-path-1.rs:10:23
+  --> $DIR/associated-types-path-1.rs:10:26
    |
 LL | pub fn f1<T>(a: T, x: T::A) {}
-   |                       ^^^^ associated type `A` not found
+   |                          ^ associated type `A` not found
 
 error[E0221]: ambiguous associated type `A` in bounds of `T`
   --> $DIR/associated-types-path-1.rs:11:34

src/test/ui/error-codes/E0220.stderr

@@ -1,8 +1,8 @@
 error[E0220]: associated type `F` not found for `Trait`
-  --> $DIR/E0220.rs:5:16
+  --> $DIR/E0220.rs:5:22
    |
 LL | type Foo = dyn Trait<F=i32>;
-   |                ^^^^^^^^^^^^ associated type `F` not found
+   |                      ^ associated type `F` not found
 
 error[E0191]: the value of the associated type `Bar` (from trait `Trait`) must be specified
   --> $DIR/E0220.rs:5:16

src/test/ui/issues/issue-23595-2.stderr

@@ -1,8 +1,8 @@
 error[E0220]: associated type `anything_here_kills_it` not found for `Self`
-  --> $DIR/issue-23595-2.rs:6:16
+  --> $DIR/issue-23595-2.rs:6:22
    |
 LL |     type B = C<Self::anything_here_kills_it>;
-   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ associated type `anything_here_kills_it` not found
+   |                      ^^^^^^^^^^^^^^^^^^^^^^ associated type `anything_here_kills_it` not found
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-39211.stderr

@@ -1,8 +1,8 @@
 error[E0220]: associated type `Row` not found for `M`
-  --> $DIR/issue-39211.rs:11:17
+  --> $DIR/issue-39211.rs:11:20
    |
 LL |     let a = [3; M::Row::DIM];
-   |                 ^^^^^^^^^^^ associated type `Row` not found
+   |                    ^^^ associated type `Row` not found
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-59029-1.stderr

@@ -1,8 +1,8 @@
 error[E0220]: associated type `Res` not found for `Self`
-  --> $DIR/issue-59029-1.rs:5:46
+  --> $DIR/issue-59029-1.rs:5:52
    |
 LL | trait MkSvc<Target, Req> = Svc<Target> where Self::Res: Svc<Req>;
-   |                                              ^^^^^^^^^ associated type `Res` not found
+   |                                                    ^^^ associated type `Res` not found
 
 error: aborting due to previous error
 

src/test/ui/span/type-binding.stderr

@@ -1,8 +1,8 @@
 error[E0220]: associated type `Trget` not found for `std::ops::Deref`
-  --> $DIR/type-binding.rs:6:14
+  --> $DIR/type-binding.rs:6:20
    |
 LL | fn homura<T: Deref<Trget = i32>>(_: T) {}
-   |                    ^^^^^^^^^^^ help: there is an associated type with a similar name: `Target`
+   |                    ^^^^^ help: there is an associated type with a similar name: `Target`
 
 error: aborting due to previous error
 

src/test/ui/type-alias-impl-trait/not_well_formed.stderr

@@ -1,8 +1,8 @@
 error[E0220]: associated type `Assoc` not found for `V`
-  --> $DIR/not_well_formed.rs:10:26
+  --> $DIR/not_well_formed.rs:10:29
    |
 LL | type Foo<V> = impl Trait<V::Assoc>;
-   |                          ^^^^^^^^ associated type `Assoc` not found
+   |                             ^^^^^ associated type `Assoc` not found
 
 error: aborting due to previous error