remove const_fn feature gate

Author: RalfJung

compiler/rustc_feature/src/active.rs

@@ -274,9 +274,6 @@ declare_features! (
     /// Allows using non lexical lifetimes (RFC 2094).
     (active, nll, "1.0.0", Some(43234), None),
 
-    /// Allows the definition of `const` functions with some advanced features.
-    (active, const_fn, "1.2.0", Some(57563), None),
-
     /// Allows associated type defaults.
     (active, associated_type_defaults, "1.2.0", Some(29661), None),
 

compiler/rustc_feature/src/removed.rs

@@ -136,6 +136,9 @@ declare_features! (
     (removed, main, "1.53.0", Some(29634), None, None),
     (removed, pub_macro_rules, "1.53.0", Some(78855), None,
      Some("removed due to being incomplete, in particular it does not work across crates")),
+     /// Allows the definition of `const` functions with some advanced features.
+    (removed, const_fn, "1.54.0", Some(57563), None,
+     Some("split into finer-grained feature gates")),
 
     // -------------------------------------------------------------------------
     // feature-group-end: removed features

library/std/src/lib.rs

@@ -246,7 +246,6 @@
 #![feature(const_cstr_unchecked)]
 #![feature(const_fn_floating_point_arithmetic)]
 #![feature(const_fn_transmute)]
-#![feature(const_fn)]
 #![feature(const_fn_fn_ptr_basics)]
 #![feature(const_io_structs)]
 #![feature(const_ip)]

src/doc/unstable-book/src/language-features/const-fn.md

@@ -1,7 +1,5 @@
 // Test internal const fn feature gate.
 
-#![feature(const_fn)]
-
 #[rustc_const_unstable(feature="fzzzzzt")] //~ stability attributes may not be used outside
 pub const fn bazinga() {}
 

src/test/ui/feature-gates/feature-gate-const_fn.rs

@@ -1,5 +1,5 @@
 error[E0734]: stability attributes may not be used outside of the standard library
-  --> $DIR/feature-gate-rustc_const_unstable.rs:5:1
+  --> $DIR/feature-gate-rustc_const_unstable.rs:3:1
    |
 LL | #[rustc_const_unstable(feature="fzzzzzt")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

src/test/ui/feature-gates/feature-gate-const_fn.stderr

@@ -3,7 +3,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 #![feature(staged_api)]
-#![feature(const_transmute, const_fn)]
+#![feature(const_transmute)]
 
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_const_stable(feature = "rust1", since = "1.0.0")]

src/test/ui/feature-gates/feature-gate-rustc_const_unstable.rs

@@ -1,5 +1,3 @@
-#![feature(const_fn)]
-
 const ARR_LEN: usize = Tt::const_val::<[i8; 123]>();
 //~^ ERROR type annotations needed