Rollup merge of #101425 - compiler-errors:point-at-ty-param, r=spastorino

Point at type parameter in plain path expr

Slightly better error message for a kinda unique use case.

Author: JohnTitor

compiler/rustc_typeck/src/check/fn_ctxt/checks.rs

@@ -1812,16 +1812,16 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             return true;
                         }
                     }
-                    // Notably, we only point to params that are local to the
-                    // item we're checking, since those are the ones we are able
-                    // to look in the final `hir::PathSegment` for. Everything else
-                    // would require a deeper search into the `qpath` than I think
-                    // is worthwhile.
-                    if let Some(param_to_point_at) = param_to_point_at
-                        && self.point_at_path_if_possible(error, def_id, param_to_point_at, qpath)
-                    {
-                        return true;
-                    }
+                }
+                // Notably, we only point to params that are local to the
+                // item we're checking, since those are the ones we are able
+                // to look in the final `hir::PathSegment` for. Everything else
+                // would require a deeper search into the `qpath` than I think
+                // is worthwhile.
+                if let Some(param_to_point_at) = param_to_point_at
+                    && self.point_at_path_if_possible(error, def_id, param_to_point_at, qpath)
+                {
+                    return true;
                 }
             }
             hir::ExprKind::MethodCall(segment, receiver, args, ..) => {

src/test/ui/typeck/point-at-type-param-in-path-expr.rs

@@ -0,0 +1,6 @@
+fn foo<T: std::fmt::Display>() {}
+
+fn main() {
+    let x = foo::<()>;
+    //~^ ERROR `()` doesn't implement `std::fmt::Display`
+}

src/test/ui/typeck/point-at-type-param-in-path-expr.stderr

@@ -0,0 +1,17 @@
+error[E0277]: `()` doesn't implement `std::fmt::Display`
+  --> $DIR/point-at-type-param-in-path-expr.rs:4:19
+   |
+LL |     let x = foo::<()>;
+   |                   ^^ `()` cannot be formatted with the default formatter
+   |
+   = help: the trait `std::fmt::Display` is not implemented for `()`
+   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
+note: required by a bound in `foo`
+  --> $DIR/point-at-type-param-in-path-expr.rs:1:11
+   |
+LL | fn foo<T: std::fmt::Display>() {}
+   |           ^^^^^^^^^^^^^^^^^ required by this bound in `foo`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.