Continue evaluating after type argument in where clause

Author: estebank

src/libsyntax/parse/parser.rs

@@ -5393,8 +5393,12 @@ impl<'a> Parser<'a> {
         // change we parse those generics now, but report an error.
         if self.choose_generics_over_qpath() {
             let generics = self.parse_generics()?;
-            self.span_err(generics.span,
-                          "generic parameters on `where` clauses are reserved for future use");
+            self.struct_span_err(
+                generics.span,
+                "generic parameters on `where` clauses are reserved for future use",
+            )
+                .span_label(generics.span, "currently unsupported")
+                .emit();
         }
 
         loop {

src/test/ui/parser/where_with_bound.rs

@@ -1,4 +1,5 @@
 fn foo<T>() where <T>::Item: ToString, T: Iterator { }
 //~^ ERROR generic parameters on `where` clauses are reserved for future use
+//~| ERROR cannot find type `Item` in the crate root
 
 fn main() {}

src/test/ui/parser/where_with_bound.stderr

@@ -2,7 +2,14 @@ error: generic parameters on `where` clauses are reserved for future use
   --> $DIR/where_with_bound.rs:1:19
    |
 LL | fn foo<T>() where <T>::Item: ToString, T: Iterator { }
-   |                   ^^^
+   |                   ^^^ currently unsupported
 
-error: aborting due to previous error
+error[E0412]: cannot find type `Item` in the crate root
+  --> $DIR/where_with_bound.rs:1:24
+   |
+LL | fn foo<T>() where <T>::Item: ToString, T: Iterator { }
+   |                        ^^^^ not found in the crate root
+
+error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0412`.