Rollup merge of #68763 - JohnTitor:do-not-sugg-dup-bounds, r=estebank

Do not suggest duplicate bounds

Fixes #68205
Fixes #68695

r? @estebank

src/librustc_typeck/check/method/suggest.rs

@@ -853,9 +853,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 } else {
                                     sp
                                 };
-                                // FIXME: contrast `t.def_id` against `param.bounds` to not suggest
-                                // traits already there. That can happen when the cause is that
-                                // we're in a const scope or associated function used as a method.
+                                let trait_def_ids: FxHashSet<DefId> = param
+                                    .bounds
+                                    .iter()
+                                    .filter_map(|bound| bound.trait_def_id())
+                                    .collect();
+                                if !candidates.iter().any(|t| trait_def_ids.contains(&t.def_id)) {
                                     err.span_suggestions(
                                         sp,
                                         &message(format!(
@@ -873,6 +876,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                         }),
                                         Applicability::MaybeIncorrect,
                                     );
+                                }
                                 suggested = true;
                             }
                             Node::Item(hir::Item {

src/test/ui/associated-item/associated-item-duplicate-bounds.rs

@@ -0,0 +1,11 @@
+trait Adapter {
+    const LINKS: usize;
+}
+
+struct Foo<A: Adapter> {
+    adapter: A,
+    links: [u32; A::LINKS], // Shouldn't suggest bounds already there.
+    //~^ ERROR: no associated item named `LINKS` found
+}
+
+fn main() {}

src/test/ui/associated-item/associated-item-duplicate-bounds.stderr

@@ -0,0 +1,11 @@
+error[E0599]: no associated item named `LINKS` found for type parameter `A` in the current scope
+  --> $DIR/associated-item-duplicate-bounds.rs:7:21
+   |
+LL |     links: [u32; A::LINKS], // Shouldn't suggest bounds already there.
+   |                     ^^^^^ associated item not found in `A`
+   |
+   = help: items from traits can only be used if the type parameter is bounded by the trait
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0599`.

src/test/ui/issues/issue-39559.stderr

@@ -5,10 +5,6 @@ LL |     entries: [T; D::dim()],
    |                     ^^^ function or associated item not found in `D`
    |
    = help: items from traits can only be used if the type parameter is bounded by the trait
-help: the following trait defines an item `dim`, perhaps you need to restrict type parameter `D` with it:
-   |
-LL | pub struct Vector<T, D: Dim + Dim> {
-   |                      ^^^^^^^^
 
 error: aborting due to previous error
 

src/test/ui/span/issue-7575.stderr

@@ -61,7 +61,10 @@ error[E0599]: no method named `is_str` found for type parameter `T` in the curre
   --> $DIR/issue-7575.rs:70:7
    |
 LL |     t.is_str()
-   |       ^^^^^^ this is an associated function, not a method
+   |     --^^^^^^--
+   |     | |
+   |     | this is an associated function, not a method
+   |     help: disambiguate the method call for the candidate: `ManyImplTrait::is_str(t)`
    |
    = note: found the following associated functions; to be used as methods, functions must have a `self` parameter
 note: the candidate is defined in the trait `ManyImplTrait`
@@ -70,14 +73,6 @@ note: the candidate is defined in the trait `ManyImplTrait`
 LL |     fn is_str() -> bool {
    |     ^^^^^^^^^^^^^^^^^^^
    = help: items from traits can only be used if the type parameter is bounded by the trait
-help: disambiguate the method call for the candidate
-   |
-LL |     ManyImplTrait::is_str(t)
-   |
-help: the following trait defines an item `is_str`, perhaps you need to restrict type parameter `T` with it:
-   |
-LL | fn param_bound<T: ManyImplTrait + ManyImplTrait>(t: T) -> bool {
-   |                ^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 3 previous errors