Stabilize universal_impl_trait

Author: cramertj

src/doc/unstable-book/src/language-features/universal-impl-trait.md

@@ -989,13 +989,6 @@ impl<'a> LoweringContext<'a> {
                         }, lifetimes)
                     },
                     ImplTraitContext::Universal(def_id) => {
-                        let has_feature = self.sess.features_untracked().universal_impl_trait;
-                        if !t.span.allows_unstable() && !has_feature {
-                            emit_feature_err(&self.sess.parse_sess, "universal_impl_trait",
-                                             t.span, GateIssue::Language,
-                                             "`impl Trait` in argument position is experimental");
-                        }
-
                         let def_node_id = self.next_id().node_id;
 
                         // Add a definition for the in-band TyParam

src/librustc/hir/lowering.rs

@@ -70,7 +70,7 @@
 #![feature(specialization)]
 #![feature(unboxed_closures)]
 #![feature(underscore_lifetimes)]
-#![feature(universal_impl_trait)]
+#![cfg_attr(stage0, feature(universal_impl_trait))]
 #![feature(trace_macros)]
 #![feature(trusted_len)]
 #![feature(catch_expr)]

src/librustc/lib.rs

@@ -34,7 +34,7 @@
 #![feature(underscore_lifetimes)]
 #![feature(macro_vis_matcher)]
 #![feature(allow_internal_unstable)]
-#![feature(universal_impl_trait)]
+#![cfg_attr(stage0, feature(universal_impl_trait))]
 
 #![cfg_attr(unix, feature(libc))]
 #![cfg_attr(test, feature(test))]

src/librustc_data_structures/lib.rs

@@ -4600,7 +4600,6 @@ This error indicates that there is a mismatch between generic parameters and
 impl Trait parameters in a trait declaration versus its impl.
 
 ```compile_fail,E0643
-#![feature(universal_impl_trait)]
 trait Foo {
     fn foo(&self, _: &impl Iterator);
 }

src/librustc_typeck/diagnostics.rs

@@ -279,9 +279,6 @@ declare_features! (
     // Allows `impl Trait` in function return types.
     (active, conservative_impl_trait, "1.12.0", Some(34511), None),
 
-    // Allows `impl Trait` in function arguments.
-    (active, universal_impl_trait, "1.23.0", Some(34511), None),
-
     // Allows exhaustive pattern matching on types that contain uninhabited types.
     (active, exhaustive_patterns, "1.13.0", None, None),
 
@@ -556,6 +553,8 @@ declare_features! (
     (accepted, inclusive_range_syntax, "1.26.0", Some(28237), None),
     // allow `..=` in patterns (RFC 1192)
     (accepted, dotdoteq_in_patterns, "1.26.0", Some(28237), None),
+    // Allows `impl Trait` in function arguments.
+    (accepted, universal_impl_trait, "1.26.0", Some(34511), None),
 );
 
 // If you change this, please modify src/doc/unstable-book as well. You must

src/libsyntax/feature_gate.rs

@@ -8,7 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(universal_impl_trait)]
 use std::fmt::Debug;
 
 trait Foo {

src/test/compile-fail/impl-trait/impl-generic-mismatch-ab.rs

@@ -8,7 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(universal_impl_trait)]
 use std::fmt::Debug;
 
 trait Foo {

src/test/compile-fail/impl-trait/impl-generic-mismatch.rs

@@ -10,7 +10,7 @@
 
 //! A simple test for testing many permutations of allowedness of
 //! impl Trait
-#![feature(conservative_impl_trait, universal_impl_trait, dyn_trait)]
+#![feature(conservative_impl_trait, dyn_trait)]
 use std::fmt::Debug;
 
 // Allowed

src/test/compile-fail/impl-trait/where-allowed.rs

@@ -12,7 +12,6 @@
 //[nll] compile-flags: -Znll -Zborrowck=mir
 
 #![feature(conservative_impl_trait,
-           universal_impl_trait,
            fn_traits,
            step_trait,
            unboxed_closures,