Stabilize min_const_fn

Author: oli-obk

src/liballoc/lib.rs

@@ -86,7 +86,7 @@
 #![feature(box_syntax)]
 #![feature(cfg_target_has_atomic)]
 #![feature(coerce_unsized)]
-#![feature(min_const_fn)]
+#![cfg_attr(stage0, feature(min_const_fn))]
 #![feature(core_intrinsics)]
 #![feature(custom_attribute)]
 #![feature(dropck_eyepatch)]

src/liballoc/tests/lib.rs

@@ -11,7 +11,7 @@
 #![feature(allocator_api)]
 #![feature(alloc_system)]
 #![feature(box_syntax)]
-#![feature(min_const_fn)]
+#![cfg_attr(stage0, feature(min_const_fn))]
 #![feature(drain_filter)]
 #![feature(exact_size_is_empty)]
 #![feature(pattern)]

src/librustc/lib.rs

@@ -42,7 +42,7 @@
 
 #![feature(box_patterns)]
 #![feature(box_syntax)]
-#![feature(min_const_fn)]
+#![cfg_attr(stage0, feature(min_const_fn))]
 #![feature(core_intrinsics)]
 #![feature(drain_filter)]
 #![cfg_attr(windows, feature(libc))]

src/librustc/ty/constness.rs

@@ -65,7 +65,7 @@ impl<'a, 'tcx> TyCtxt<'a, 'tcx, 'tcx> {
                 _ => true,
             }
         } else {
-            // users enabling the `const_fn` can do what they want
+            // users enabling the `const_fn` feature gate can do what they want
             !self.sess.features_untracked().const_fn
         }
     }

src/librustc_target/lib.rs

@@ -22,7 +22,7 @@
       html_root_url = "https://doc.rust-lang.org/nightly/")]
 
 #![feature(box_syntax)]
-#![feature(min_const_fn)]
+#![cfg_attr(stage0, feature(min_const_fn))]
 #![feature(nll)]
 #![feature(slice_patterns)]
 

src/libstd/lib.rs

@@ -250,7 +250,7 @@
 #![feature(cfg_target_vendor)]
 #![feature(char_error_internals)]
 #![feature(compiler_builtins_lib)]
-#![feature(min_const_fn)]
+#![cfg_attr(stage0, feature(min_const_fn))]
 #![feature(const_int_ops)]
 #![feature(const_ip)]
 #![feature(const_raw_ptr_deref)]

src/libsyntax/attr/builtin.rs

@@ -107,8 +107,7 @@ pub struct Stability {
     pub level: StabilityLevel,
     pub feature: Symbol,
     pub rustc_depr: Option<RustcDeprecation>,
-    /// `None` means the function is stable but needs to be allowed by the
-    /// `min_const_fn` feature
+    /// `None` means the function is stable but needs to be a stable const fn, too
     /// `Some` contains the feature gate required to be able to use the function
     /// as const fn
     pub const_stability: Option<Symbol>,

src/libsyntax/feature_gate.rs

@@ -1806,9 +1806,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 if header.asyncness.is_async() {
                     gate_feature_post!(&self, async_await, span, "async fn is unstable");
                 }
-                if header.constness.node == ast::Constness::Const {
-                    gate_feature_post!(&self, min_const_fn, span, "const fn is unstable");
-                }
                 // stability of const fn methods are covered in
                 // visit_trait_item and visit_impl_item below; this is
                 // because default methods don't pass through this
@@ -1863,11 +1860,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
         }
 
         match ii.node {
-            ast::ImplItemKind::Method(ref sig, _) => {
-                if sig.header.constness.node == ast::Constness::Const {
-                    gate_feature_post!(&self, min_const_fn, ii.span, "const fn is unstable");
-                }
-            }
+            ast::ImplItemKind::Method(..) => {}
             ast::ImplItemKind::Existential(..) => {
                 gate_feature_post!(
                     &self,

src/test/codegen-units/item-collection/unreferenced-const-fn.rs

@@ -13,7 +13,6 @@
 
 // NB: We do not expect *any* monomorphization to be generated here.
 
-#![feature(min_const_fn)]
 #![deny(dead_code)]
 #![crate_type = "rlib"]
 

src/test/codegen/link-dead-code.rs

@@ -10,7 +10,6 @@
 
 // compile-flags:-Clink-dead-code
 
-#![feature(min_const_fn)]
 #![crate_type = "rlib"]
 
 // This test makes sure that, when -Clink-dead-code is specified, we generate