Stabilize underscore lifetimes

Author: cramertj

src/librustc/lib.rs

@@ -68,7 +68,7 @@
 #![feature(slice_patterns)]
 #![feature(specialization)]
 #![feature(unboxed_closures)]
-#![feature(underscore_lifetimes)]
+#![cfg_attr(stage0, feature(underscore_lifetimes))]
 #![cfg_attr(stage0, feature(universal_impl_trait))]
 #![feature(trace_macros)]
 #![feature(trusted_len)]

src/librustc_data_structures/lib.rs

@@ -30,7 +30,7 @@
 #![cfg_attr(stage0, feature(i128_type, i128))]
 #![feature(specialization)]
 #![feature(optin_builtin_traits)]
-#![feature(underscore_lifetimes)]
+#![cfg_attr(stage0, feature(underscore_lifetimes))]
 #![feature(macro_vis_matcher)]
 #![feature(allow_internal_unstable)]
 #![cfg_attr(stage0, feature(universal_impl_trait))]

src/librustc_mir/lib.rs

@@ -37,7 +37,7 @@ Rust MIR: a lowered representation of Rust. Also: an experiment!
 #![feature(placement_in_syntax)]
 #![feature(collection_placement)]
 #![feature(nonzero)]
-#![feature(underscore_lifetimes)]
+#![cfg_attr(stage0, feature(underscore_lifetimes))]
 #![cfg_attr(stage0, feature(never_type))]
 #![feature(inclusive_range_fields)]
 

src/librustc_traits/lib.rs

@@ -15,7 +15,7 @@
 
 #![feature(crate_visibility_modifier)]
 #![cfg_attr(stage0, feature(match_default_bindings))]
-#![feature(underscore_lifetimes)]
+#![cfg_attr(stage0, feature(underscore_lifetimes))]
 
 #[macro_use]
 extern crate log;

src/libsyntax/feature_gate.rs

@@ -385,6 +385,9 @@ declare_features! (
     // allow `'_` placeholder lifetimes
     (active, underscore_lifetimes, "1.22.0", Some(44524), None),
 
+    // Default match binding modes (RFC 2005)
+    (active, match_default_bindings, "1.22.0", Some(42640), None),
+
     // Trait object syntax with `dyn` prefix
     (active, dyn_trait, "1.22.0", Some(44662), Some(Edition::Edition2018)),
 
@@ -562,6 +565,8 @@ declare_features! (
     (accepted, i128_type, "1.26.0", Some(35118), None),
     // Default match binding modes (RFC 2005)
     (accepted, match_default_bindings, "1.26.0", Some(42640), None),
+    // allow `'_` placeholder lifetimes
+    (accepted, underscore_lifetimes, "1.26.0", Some(44524), None),
 );
 
 // If you change this, please modify src/doc/unstable-book as well. You must
@@ -1792,14 +1797,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
 
         visit::walk_generic_param(self, param)
     }
-
-    fn visit_lifetime(&mut self, lt: &'a ast::Lifetime) {
-        if lt.ident.name == keywords::UnderscoreLifetime.name() {
-            gate_feature_post!(&self, underscore_lifetimes, lt.span,
-                               "underscore lifetimes are unstable");
-        }
-        visit::walk_lifetime(self, lt)
-    }
 }
 
 pub fn get_features(span_handler: &Handler, krate_attrs: &[ast::Attribute],

src/test/compile-fail/closure-expected-type/expect-fn-supply-fn-multiple.rs

@@ -10,7 +10,6 @@
 
 // must-compile-successfully
 
-#![feature(underscore_lifetimes)]
 #![allow(warnings)]
 
 type Different<'a, 'b> = &'a mut (&'a (), &'b ());

src/test/compile-fail/closure-expected-type/expect-fn-supply-fn.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(underscore_lifetimes)]
-
 fn with_closure_expecting_fn_with_free_region<F>(_: F)
     where F: for<'a> FnOnce(fn(&'a u32), &i32)
 {

src/test/compile-fail/underscore-lifetime-binders.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(underscore_lifetimes)]
-
 struct Foo<'a>(&'a u8);
 struct Baz<'a>(&'_ &'a u8); //~ ERROR missing lifetime specifier
 

src/test/compile-fail/underscore-lifetime-elison-mismatch.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(underscore_lifetimes)]
-
 fn foo(x: &mut Vec<&'_ u8>, y: &'_ u8) { x.push(y); } //~ ERROR lifetime mismatch
 
 fn main() {}

src/test/run-pass/impl-trait/lifetimes.rs

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