Merge #4833

4833: Separating parsing of `for` in predicates and types r=matklad a=matthewjasper

We now correctly accept `for<'a> (&'a F): Fn(&'a str)` in a where clause and correctly reject `for<'a> &'a u32` as a type.

Co-authored-by: Matthew Jasper <[email protected]>

2 files changed, 14 insertions, 8 deletions

diff --git a/crates/ra_parser/src/grammar/type_params.rs b/crates/ra_parser/src/grammar/type_params.rs
index 50e4900c3..325d566ad 100644
--- a/crates/ra_parser/src/grammar/type_params.rs
+++ b/crates/ra_parser/src/grammar/type_params.rs
@@ -191,10 +191,14 @@ fn where_predicate(p: &mut Parser) {
         }
         _ => {
             // test where_pred_for
-            // fn test<F>()
+            // fn for_trait<F>()
             // where
             //    for<'a> F: Fn(&'a str)
             // { }
+            if p.at(T![for]) {
+                types::for_binder(p);
+            }
+
             types::type_(p);
 
             if p.at(T![:]) {
diff --git a/crates/ra_parser/src/grammar/types.rs b/crates/ra_parser/src/grammar/types.rs
index fe1a039cb..9e8e3bd97 100644
--- a/crates/ra_parser/src/grammar/types.rs
+++ b/crates/ra_parser/src/grammar/types.rs
@@ -216,19 +216,21 @@ pub(super) fn for_binder(p: &mut Parser) {
 
 // test for_type
 // type A = for<'a> fn() -> ();
-// fn foo<T>(_t: &T) where for<'a> &'a T: Iterator {}
-// fn bar<T>(_t: &T) where for<'a> &'a mut T: Iterator {}
-// fn baz<T>(_t: &T) where for<'a> <&'a T as Baz>::Foo: Iterator {}
+// type B = for<'a> unsafe extern "C" fn(&'a ()) -> ();
+// type Obj = for<'a> PartialEq<&'a i32>;
 pub(super) fn for_type(p: &mut Parser) {
     assert!(p.at(T![for]));
     let m = p.start();
     for_binder(p);
     match p.current() {
-        T![fn] | T![unsafe] | T![extern] => fn_pointer_type(p),
-        T![&] => reference_type(p),
-        _ if paths::is_path_start(p) => path_type_(p, false),
-        _ => p.error("expected a path"),
+        T![fn] | T![unsafe] | T![extern] => {}
+        // OK: legacy trait object format
+        _ if paths::is_use_path_start(p) => {}
+        _ => {
+            p.error("expected a function pointer or path");
+        }
     }
+    type_no_bounds(p);
     m.complete(p, FOR_TYPE);
 }