Revert "Revert stabilizing integer::BITS."

compiler/rustc_data_structures/src/lib.rs

@@ -13,7 +13,6 @@
 #![feature(unboxed_closures)]
 #![feature(generator_trait)]
 #![feature(fn_traits)]
-#![feature(int_bits_const)]
 #![feature(min_specialization)]
 #![feature(auto_traits)]
 #![feature(nll)]

compiler/rustc_serialize/src/lib.rs

@@ -16,7 +16,6 @@
 #![feature(min_specialization)]
 #![feature(vec_spare_capacity)]
 #![feature(core_intrinsics)]
-#![feature(int_bits_const)]
 #![feature(maybe_uninit_array_assume_init)]
 #![feature(maybe_uninit_uninit_array)]
 #![feature(maybe_uninit_slice)]

compiler/rustc_serialize/tests/leb128.rs

-#![feature(int_bits_const)]
 #![feature(maybe_uninit_slice)]
 #![feature(maybe_uninit_uninit_array)]
 

library/alloc/src/lib.rs

@@ -103,7 +103,6 @@
 #![feature(fn_traits)]
 #![feature(fundamental)]
 #![feature(inplace_iteration)]
-#![feature(int_bits_const)]
 // Technically, this is a bug in rustdoc: rustdoc sees the documentation on `#[lang = slice_alloc]`
 // blocks is for `&[T]`, which also has documentation using this feature in `core`, and gets mad
 // that the feature-gate isn't enabled. Ideally, it wouldn't check for the feature gate for docs

library/alloc/tests/lib.rs

@@ -16,7 +16,6 @@
 #![feature(binary_heap_retain)]
 #![feature(inplace_iteration)]
 #![feature(iter_map_while)]
-#![feature(int_bits_const)]
 #![feature(vecdeque_binary_search)]
 #![feature(slice_group_by)]
 #![feature(slice_partition_dedup)]

library/core/src/num/int_macros.rs

@@ -32,10 +32,9 @@
         /// # Examples
         ///
         /// ```
-        /// #![feature(int_bits_const)]
         #[doc = concat!("assert_eq!(", stringify!($SelfT), "::BITS, ", stringify!($BITS), ");")]
         /// ```
-        #[unstable(feature = "int_bits_const", issue = "76904")]
+        #[stable(feature = "int_bits_const", since = "1.51.0")]
         pub const BITS: u32 = $BITS;
 
         /// Converts a string slice in a given base to an integer.

library/core/src/num/uint_macros.rs

@@ -32,10 +32,9 @@
         /// # Examples
         ///
         /// ```
-        /// #![feature(int_bits_const)]
         #[doc = concat!("assert_eq!(", stringify!($SelfT), "::BITS, ", stringify!($BITS), ");")]
         /// ```
-        #[unstable(feature = "int_bits_const", issue = "76904")]
+        #[stable(feature = "int_bits_const", since = "1.51.0")]
         pub const BITS: u32 = $BITS;
 
         /// Converts a string slice in a given base to an integer.

library/core/tests/lib.rs

@@ -73,7 +73,6 @@
 #![cfg_attr(not(bootstrap), feature(ptr_metadata))]
 #![feature(once_cell)]
 #![feature(unsized_tuple_coercion)]
-#![feature(int_bits_const)]
 #![feature(nonzero_leading_trailing_zeros)]
 #![feature(const_option)]
 #![feature(integer_atomics)]

library/panic_unwind/src/lib.rs

@@ -18,7 +18,6 @@
     issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/"
 )]
 #![feature(core_intrinsics)]
-#![feature(int_bits_const)]
 #![feature(lang_items)]
 #![feature(nll)]
 #![feature(panic_unwind)]