Stabilise repr128

Author: beetrees

compiler/rustc_error_codes/src/error_codes/E0658.md

@@ -3,10 +3,7 @@ An unstable feature was used.
 Erroneous code example:
 
 ```compile_fail,E0658
-#[repr(u128)] // error: use of unstable library feature 'repr128'
-enum Foo {
-    Bar(u64),
-}
+use std::intrinsics; // error: use of unstable library feature `core_intrinsics`
 ```
 
 If you're using a stable or a beta version of rustc, you won't be able to use
@@ -17,12 +14,9 @@ If you're using a nightly version of rustc, just add the corresponding feature
 to be able to use it:
 
 ```
-#![feature(repr128)]
+#![feature(core_intrinsics)]
 
-#[repr(u128)] // ok!
-enum Foo {
-    Bar(u64),
-}
+use std::intrinsics; // ok!
 ```
 
 [rustup]: https://rust-lang.github.io/rustup/concepts/channels.html

compiler/rustc_feature/src/accepted.rs

@@ -350,6 +350,8 @@ declare_features! (
     (accepted, relaxed_adts, "1.19.0", Some(35626)),
     /// Lessens the requirements for structs to implement `Unsize`.
     (accepted, relaxed_struct_unsize, "1.58.0", Some(81793)),
+    /// Allows the `#[repr(i128)]` attribute for enums.
+    (accepted, repr128, "CURRENT_RUSTC_VERSION", Some(56071)),
     /// Allows `repr(align(16))` struct attribute (RFC 1358).
     (accepted, repr_align, "1.25.0", Some(33626)),
     /// Allows using `#[repr(align(X))]` on enums with equivalent semantics

compiler/rustc_feature/src/unstable.rs

@@ -612,8 +612,6 @@ declare_features! (
     (incomplete, ref_pat_eat_one_layer_2024_structural, "1.81.0", Some(123076)),
     /// Allows using the `#[register_tool]` attribute.
     (unstable, register_tool, "1.41.0", Some(66079)),
-    /// Allows the `#[repr(i128)]` attribute for enums.
-    (incomplete, repr128, "1.16.0", Some(56071)),
     /// Allows `repr(simd)` and importing the various simd intrinsics.
     (unstable, repr_simd, "1.4.0", Some(27731)),
     /// Allows bounding the return type of AFIT/RPITIT.

compiler/rustc_hir_analysis/src/check/check.rs

@@ -20,7 +20,7 @@ use rustc_middle::middle::stability::EvalResult;
 use rustc_middle::ty::error::TypeErrorToStringExt;
 use rustc_middle::ty::fold::{BottomUpFolder, fold_regions};
 use rustc_middle::ty::layout::{LayoutError, MAX_SIMD_LANES};
-use rustc_middle::ty::util::{Discr, IntTypeExt};
+use rustc_middle::ty::util::Discr;
 use rustc_middle::ty::{
     AdtDef, GenericArgKind, RegionKind, TypeSuperVisitable, TypeVisitable, TypeVisitableExt,
 };
@@ -1441,19 +1441,6 @@ fn check_enum(tcx: TyCtxt<'_>, def_id: LocalDefId) {
         );
     }
 
-    let repr_type_ty = def.repr().discr_type().to_ty(tcx);
-    if repr_type_ty == tcx.types.i128 || repr_type_ty == tcx.types.u128 {
-        if !tcx.features().repr128() {
-            feature_err(
-                &tcx.sess,
-                sym::repr128,
-                tcx.def_span(def_id),
-                "repr with 128-bit type is unstable",
-            )
-            .emit();
-        }
-    }
-
     for v in def.variants() {
         if let ty::VariantDiscr::Explicit(discr_def_id) = v.discr {
             tcx.ensure_ok().typeck(discr_def_id.expect_local());

src/doc/unstable-book/src/language-features/repr128.md

@@ -1,5 +1,4 @@
-#![feature(repr128, proc_macro_hygiene, proc_macro_quote, box_patterns)]
-#![allow(incomplete_features)]
+#![feature(proc_macro_hygiene, proc_macro_quote, box_patterns)]
 #![allow(clippy::useless_conversion, clippy::uninlined_format_args)]
 
 extern crate proc_macro;

src/tools/clippy/tests/ui/auxiliary/proc_macro_attr.rs

@@ -1,5 +1,4 @@
-#![feature(repr128, proc_macro_quote, proc_macro_span)]
-#![allow(incomplete_features)]
+#![feature(proc_macro_quote, proc_macro_span)]
 #![allow(clippy::field_reassign_with_default)]
 #![allow(clippy::eq_op)]
 #![allow(clippy::literal_string_with_formatting_args)]

src/tools/clippy/tests/ui/auxiliary/proc_macro_derive.rs

@@ -1,7 +1,5 @@
 //@no-rustfix
 
-#![feature(repr128)]
-#![allow(incomplete_features)]
 #![warn(
     clippy::cast_precision_loss,
     clippy::cast_possible_truncation,