Add universal_impl_trait feature gate

Move feature gate check to inside HIR lowering. Change error messages
and update tests.

1 files changed, 3 insertions, 4 deletions

diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index b6cb3ac1308..97eec3a21e9 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -275,6 +275,9 @@ declare_features! (
     // Allows `impl Trait` in function return types.
     (active, conservative_impl_trait, "1.12.0", Some(34511)),
 
+    // Allows `impl Trait` in function arguments.
+    (active, universal_impl_trait, "1.23.0", Some(34511)),
+
     // The `!` type
     (active, never_type, "1.13.0", Some(35121)),
 
@@ -1451,10 +1454,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
             ast::TyKind::BareFn(ref bare_fn_ty) => {
                 self.check_abi(bare_fn_ty.abi, ty.span);
             }
-            ast::TyKind::ImplTrait(..) => {
-                gate_feature_post!(&self, conservative_impl_trait, ty.span,
-                                   "`impl Trait` is experimental");
-            }
             ast::TyKind::Never => {
                 gate_feature_post!(&self, never_type, ty.span,
                                    "The `!` type is experimental");