Rollup merge of rust-lang#118123 - RalfJung:internal-lib-features, r=compiler-errors

Add support for making lib features internal

We have the notion of an "internal" lang feature: a feature that is never intended to be stabilized, and using which can cause ICEs and other issues without that being considered a bug.

This extends that idea to lib features as well. It is an alternative to rust-lang#115623: instead of using an attribute to declare lib features internal, we simply do this based on the name. Everything ending in `_internals` or `_internal` is considered internal.

Then we rename `core_intrinsics` to `core_intrinsics_internal`, which fixes rust-lang#115597.

Author: compiler-errors

alloc/tests/lib.rs

@@ -41,6 +41,7 @@
 #![feature(thin_box)]
 #![feature(strict_provenance)]
 #![feature(drain_keep_rest)]
+#![allow(internal_features)]
 #![deny(fuzzy_provenance_casts)]
 #![deny(unsafe_op_in_unsafe_fn)]
 

core/src/intrinsics.rs

@@ -1906,6 +1906,7 @@ extern "rust-intrinsic" {
     ///
     /// ```
     /// #![feature(core_intrinsics)]
+    /// # #![allow(internal_features)]
     ///
     /// use std::intrinsics::ctlz;
     ///
@@ -1918,6 +1919,7 @@ extern "rust-intrinsic" {
     ///
     /// ```
     /// #![feature(core_intrinsics)]
+    /// # #![allow(internal_features)]
     ///
     /// use std::intrinsics::ctlz;
     ///
@@ -1939,6 +1941,7 @@ extern "rust-intrinsic" {
     ///
     /// ```
     /// #![feature(core_intrinsics)]
+    /// # #![allow(internal_features)]
     ///
     /// use std::intrinsics::ctlz_nonzero;
     ///
@@ -1965,6 +1968,7 @@ extern "rust-intrinsic" {
     ///
     /// ```
     /// #![feature(core_intrinsics)]
+    /// # #![allow(internal_features)]
     ///
     /// use std::intrinsics::cttz;
     ///
@@ -1977,6 +1981,7 @@ extern "rust-intrinsic" {
     ///
     /// ```
     /// #![feature(core_intrinsics)]
+    /// # #![allow(internal_features)]
     ///
     /// use std::intrinsics::cttz;
     ///
@@ -1998,6 +2003,7 @@ extern "rust-intrinsic" {
     ///
     /// ```
     /// #![feature(core_intrinsics)]
+    /// # #![allow(internal_features)]
     ///
     /// use std::intrinsics::cttz_nonzero;
     ///
@@ -2463,6 +2469,7 @@ extern "rust-intrinsic" {
     /// ```no_run
     /// #![feature(const_eval_select)]
     /// #![feature(core_intrinsics)]
+    /// # #![allow(internal_features)]
     /// use std::hint::unreachable_unchecked;
     /// use std::intrinsics::const_eval_select;
     ///

core/tests/lib.rs

@@ -117,6 +117,7 @@
 #![feature(get_many_mut)]
 #![feature(offset_of)]
 #![feature(iter_map_windows)]
+#![allow(internal_features)]
 #![deny(unsafe_op_in_unsafe_fn)]
 #![deny(fuzzy_provenance_casts)]