Continue evaluating after missing for in impl Trait for Foo

Author: estebank

src/libsyntax/parse/parser.rs

@@ -6055,7 +6055,13 @@ impl<'a> Parser<'a> {
             Some(ty_second) => {
                 // impl Trait for Type
                 if !has_for {
-                    self.span_err(missing_for_span, "missing `for` in a trait impl");
+                    self.struct_span_err(missing_for_span, "missing `for` in a trait impl")
+                        .span_suggestion_short_with_applicability(
+                            missing_for_span,
+                            "add `for` here",
+                            " for ".to_string(),
+                            Applicability::MachineApplicable,
+                        ).emit();
                 }
 
                 let ty_first = ty_first.into_inner();

src/test/ui/parser/impl-parsing.stderr

@@ -2,13 +2,13 @@ error: missing `for` in a trait impl
   --> $DIR/impl-parsing.rs:6:11
    |
 LL | impl Trait Type {} //~ ERROR missing `for` in a trait impl
-   |           ^
+   |           ^ help: add `for` here
 
 error: missing `for` in a trait impl
   --> $DIR/impl-parsing.rs:7:11
    |
 LL | impl Trait .. {} //~ ERROR missing `for` in a trait impl
-   |           ^
+   |           ^ help: add `for` here
 
 error: expected a trait, found type
   --> $DIR/impl-parsing.rs:8:6

src/test/ui/parser/issue-27255.rs

@@ -1,3 +1,10 @@
-impl A .. {} //~ ERROR
+trait A {}
+
+impl A .. {}
+//~^ ERROR missing `for` in a trait impl
+//~| ERROR `impl Trait for .. {}` is an obsolete syntax
+
+impl A      usize {}
+//~^ ERROR missing `for` in a trait impl
 
 fn main() {}

src/test/ui/parser/issue-27255.stderr

@@ -1,8 +1,22 @@
 error: missing `for` in a trait impl
-  --> $DIR/issue-27255.rs:1:7
+  --> $DIR/issue-27255.rs:3:7
    |
-LL | impl A .. {} //~ ERROR
-   |       ^
+LL | impl A .. {}
+   |       ^ help: add `for` here
 
-error: aborting due to previous error
+error: missing `for` in a trait impl
+  --> $DIR/issue-27255.rs:7:7
+   |
+LL | impl A      usize {}
+   |       ^^^^^^ help: add `for` here
+
+error: `impl Trait for .. {}` is an obsolete syntax
+  --> $DIR/issue-27255.rs:3:1
+   |
+LL | impl A .. {}
+   | ^^^^^^^^^^^^
+   |
+   = help: use `auto trait Trait {}` instead
+
+error: aborting due to 3 previous errors