[experiment][3] meowww

compiler/rustc_arena/src/lib.rs

@@ -10,12 +10,12 @@
 // tidy-alphabetical-start
 #![allow(clippy::mut_from_ref)] // Arena allocators are one place where this pattern is fine.
 #![allow(internal_features)]
+#![cfg_attr(bootstrap, feature(never_type))]
 #![cfg_attr(test, feature(test))]
 #![deny(unsafe_op_in_unsafe_fn)]
 #![doc(test(no_crate_inject, attr(deny(warnings), allow(internal_features))))]
 #![feature(decl_macro)]
 #![feature(dropck_eyepatch)]
-#![feature(never_type)]
 #![feature(rustc_attrs)]
 #![feature(unwrap_infallible)]
 // tidy-alphabetical-end

compiler/rustc_ast_ir/src/lib.rs

@@ -6,8 +6,8 @@
 //! `rustc_type_ir` for a single import.
 
 // tidy-alphabetical-start
+#![cfg_attr(all(feature = "nightly", bootstrap), feature(never_type))]
 #![cfg_attr(feature = "nightly", allow(internal_features))]
-#![cfg_attr(feature = "nightly", feature(never_type))]
 #![cfg_attr(feature = "nightly", feature(rustc_attrs))]
 // tidy-alphabetical-end
 

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -288,9 +288,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 // Function pointers cannot be `const`
                 self.check_late_bound_lifetime_defs(&fn_ptr_ty.generic_params);
             }
-            ast::TyKind::Never => {
-                gate!(self, never_type, ty.span, "the `!` type is experimental");
-            }
             ast::TyKind::Pat(..) => {
                 gate!(self, pattern_types, ty.span, "pattern types are unstable");
             }
@@ -318,15 +315,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
     }
 
     fn visit_generic_args(&mut self, args: &'a ast::GenericArgs) {
-        // This check needs to happen here because the never type can be returned from a function,
-        // but cannot be used in any other context. If this check was in `visit_fn_ret_ty`, it
-        // include both functions and generics like `impl Fn() -> !`.
-        if let ast::GenericArgs::Parenthesized(generic_args) = args
-            && let ast::FnRetTy::Ty(ref ty) = generic_args.output
-            && matches!(ty.kind, ast::TyKind::Never)
-        {
-            gate!(self, never_type, ty.span, "the `!` type is experimental");
-        }
         visit::walk_generic_args(self, args);
     }
 

compiler/rustc_borrowck/src/lib.rs

@@ -2,11 +2,11 @@
 
 // tidy-alphabetical-start
 #![allow(internal_features)]
+#![cfg_attr(bootstrap, feature(never_type))]
 #![feature(box_patterns)]
 #![feature(default_field_values)]
 #![feature(file_buffered)]
 #![feature(negative_impls)]
-#![feature(never_type)]
 #![feature(rustc_attrs)]
 #![feature(stmt_expr_attributes)]
 #![feature(try_blocks)]

compiler/rustc_const_eval/src/lib.rs

@@ -1,8 +1,8 @@
 // tidy-alphabetical-start
+#![cfg_attr(bootstrap, feature(never_type))]
 #![feature(array_try_map)]
 #![feature(box_patterns)]
 #![feature(decl_macro)]
-#![feature(never_type)]
 #![feature(slice_ptr_get)]
 #![feature(trait_alias)]
 #![feature(unqualified_local_imports)]

compiler/rustc_data_structures/src/lib.rs

@@ -10,6 +10,7 @@
 #![allow(internal_features)]
 #![allow(rustc::default_hash_types)]
 #![allow(rustc::potential_query_instability)]
+#![cfg_attr(bootstrap, feature(never_type))]
 #![cfg_attr(test, feature(test))]
 #![deny(unsafe_op_in_unsafe_fn)]
 #![feature(allocator_api)]
@@ -24,7 +25,6 @@
 #![feature(map_try_insert)]
 #![feature(min_specialization)]
 #![feature(negative_impls)]
-#![feature(never_type)]
 #![feature(pattern_type_macro)]
 #![feature(pattern_types)]
 #![feature(ptr_alignment_type)]

compiler/rustc_error_codes/src/error_codes/E0725.md

@@ -4,8 +4,9 @@ command line flags.
 Erroneous code example:
 
 ```ignore (can't specify compiler flags from doctests)
-#![feature(never_type)] // error: the feature `never_type` is not in
-                        // the list of allowed features
+#![feature(extern_item_impls)]
+//~^ error: the feature `extern_item_impls`
+//          is not in the list of allowed features
 ```
 
 Delete the offending feature attribute, or add it to the list of allowed

compiler/rustc_errors/src/lib.rs

@@ -5,11 +5,11 @@
 // tidy-alphabetical-start
 #![allow(internal_features)]
 #![allow(rustc::direct_use_of_rustc_type_ir)]
+#![cfg_attr(bootstrap, feature(never_type))]
 #![feature(associated_type_defaults)]
 #![feature(default_field_values)]
 #![feature(macro_metavar_expr_concat)]
 #![feature(negative_impls)]
-#![feature(never_type)]
 #![feature(rustc_attrs)]
 // tidy-alphabetical-end
 

compiler/rustc_feature/src/accepted.rs

@@ -326,6 +326,8 @@ declare_features! (
     (accepted, native_link_modifiers_verbatim, "1.67.0", Some(81490)),
     /// Allows specifying the whole-archive link modifier
     (accepted, native_link_modifiers_whole_archive, "1.61.0", Some(81490)),
+    /// Allows the `!` type.
+    (accepted, never_type, "CURRENT_RUSTC_VERSION", Some(35121)),
     /// Allows using non lexical lifetimes (RFC 2094).
     (accepted, nll, "1.63.0", Some(43234)),
     /// Allows using `#![no_std]`.

compiler/rustc_feature/src/unstable.rs

@@ -622,8 +622,6 @@ declare_features! (
     (unstable, negative_impls, "1.44.0", Some(68318)),
     /// Allows the `!` pattern.
     (incomplete, never_patterns, "1.76.0", Some(118155)),
-    /// Allows the `!` type. Does not imply 'exhaustive_patterns' (below) any more.
-    (unstable, never_type, "1.13.0", Some(35121)),
     /// Switch `..` syntax to use the new (`Copy + IntoIterator`) range types.
     (unstable, new_range, "1.86.0", Some(123741)),
     /// Allows `#![no_core]`.

compiler/rustc_hir/src/lib.rs

@@ -3,13 +3,13 @@
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/hir.html
 
 // tidy-alphabetical-start
+#![cfg_attr(bootstrap, feature(never_type))]
 #![feature(associated_type_defaults)]
 #![feature(closure_track_caller)]
 #![feature(const_default)]
 #![feature(const_trait_impl)]
 #![feature(derive_const)]
 #![feature(exhaustive_patterns)]
-#![feature(never_type)]
 #![feature(variant_count)]
 #![recursion_limit = "256"]
 // tidy-alphabetical-end

compiler/rustc_hir_analysis/src/lib.rs

@@ -56,10 +56,10 @@ This API is completely unstable and subject to change.
 */
 
 // tidy-alphabetical-start
+#![cfg_attr(bootstrap, feature(never_type))]
 #![feature(default_field_values)]
 #![feature(gen_blocks)]
 #![feature(iter_intersperse)]
-#![feature(never_type)]
 #![feature(slice_partition_dedup)]
 #![feature(try_blocks)]
 #![feature(unwrap_infallible)]

compiler/rustc_hir_typeck/src/lib.rs

@@ -1,8 +1,8 @@
 // tidy-alphabetical-start
+#![cfg_attr(bootstrap, feature(never_type))]
 #![feature(box_patterns)]
 #![feature(iter_intersperse)]
 #![feature(iter_order_by)]
-#![feature(never_type)]
 #![feature(trim_prefix_suffix)]
 // tidy-alphabetical-end
 

compiler/rustc_macros/src/lib.rs

@@ -1,6 +1,6 @@
 // tidy-alphabetical-start
 #![allow(rustc::default_hash_types)]
-#![feature(never_type)]
+#![cfg_attr(bootstrap, feature(never_type))]
 #![feature(proc_macro_diagnostic)]
 #![feature(proc_macro_tracked_env)]
 // tidy-alphabetical-end

compiler/rustc_metadata/src/lib.rs

@@ -1,11 +1,11 @@
 // tidy-alphabetical-start
 #![allow(internal_features)]
+#![cfg_attr(bootstrap, feature(never_type))]
 #![feature(error_iter)]
 #![feature(file_buffered)]
 #![feature(gen_blocks)]
 #![feature(macro_metavar_expr)]
 #![feature(min_specialization)]
-#![feature(never_type)]
 #![feature(proc_macro_internals)]
 #![feature(result_option_map_or_default)]
 #![feature(strip_circumfix)]

compiler/rustc_middle/src/lib.rs

@@ -27,6 +27,7 @@
 // tidy-alphabetical-start
 #![allow(internal_features)]
 #![allow(rustc::direct_use_of_rustc_type_ir)]
+#![cfg_attr(bootstrap, feature(never_type))]
 #![cfg_attr(doc, feature(intra_doc_pointers))]
 #![feature(allocator_api)]
 #![feature(associated_type_defaults)]
@@ -44,7 +45,6 @@
 #![feature(gen_blocks)]
 #![feature(min_specialization)]
 #![feature(negative_impls)]
-#![feature(never_type)]
 #![feature(ptr_alignment_type)]
 #![feature(range_bounds_is_empty)]
 #![feature(rustc_attrs)]

compiler/rustc_middle/src/ty/inhabitedness/mod.rs

@@ -5,7 +5,7 @@
 //!
 //! # Example
 //! ```rust
-//! #![feature(never_type)]
+#![cfg_attr(bootstrap, doc = "#![feature(never_type)]")]
 //! mod a {
 //!     pub mod b {
 //!         pub struct SecretlyUninhabited {
@@ -141,7 +141,7 @@ impl<'tcx> Ty<'tcx> {
     ///
     /// # Example
     /// ```
-    /// #![feature(never_type)]
+    #[cfg_attr(bootstrap, doc = "#![feature(never_type)]")]
     /// # fn main() {}
     /// enum Void {}
     /// mod a {

compiler/rustc_mir_dataflow/src/lib.rs

@@ -1,9 +1,9 @@
 // tidy-alphabetical-start
+#![cfg_attr(bootstrap, feature(never_type))]
 #![feature(associated_type_defaults)]
 #![feature(box_patterns)]
 #![feature(exact_size_is_empty)]
 #![feature(file_buffered)]
-#![feature(never_type)]
 #![feature(try_blocks)]
 // tidy-alphabetical-end
 

compiler/rustc_pattern_analysis/src/constructor.rs

@@ -94,7 +94,6 @@
 //! constructors of a type. For example, all the following is ok:
 //!
 //! ```rust,ignore(example)
-//! # #![feature(never_type)]
 //! # #![feature(exhaustive_patterns)]
 //! fn foo(x: Option<!>) {
 //!   match x {
@@ -114,8 +113,8 @@
 //! Moreover, take the following:
 //!
 //! ```rust
-//! # #![feature(never_type)]
 //! # #![feature(exhaustive_patterns)]
+#![cfg_attr(bootstrap, doc = "#![feature(never_type)]")]
 //! # let x = None::<!>;
 //! match x {
 //!   None => {}

compiler/rustc_resolve/src/late.rs

@@ -3942,8 +3942,8 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
     /// A never pattern by definition indicates an unreachable case. For example, matching on
     /// `Result<T, &!>` could look like:
     /// ```rust
-    /// # #![feature(never_type)]
     /// # #![feature(never_patterns)]
+    #[cfg_attr(bootstrap, doc = "#![feature(never_type)]")]
     /// # fn bar(_x: u32) {}
     /// let foo: Result<u32, &!> = Ok(0);
     /// match foo {
@@ -4008,8 +4008,8 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
     /// A never pattern by definition indicates an unreachable case. For example, destructuring a
     /// `Result<T, &!>` could look like:
     /// ```rust
-    /// # #![feature(never_type)]
     /// # #![feature(never_patterns)]
+    #[cfg_attr(bootstrap, doc = "#![feature(never_type)]")]
     /// # fn foo() -> Result<bool, &'static !> { Ok(true) }
     /// let (Ok(x) | Err(&!)) = foo();
     /// # let _ = x;

compiler/rustc_serialize/src/lib.rs

@@ -3,10 +3,10 @@
 // tidy-alphabetical-start
 #![allow(internal_features)]
 #![allow(rustc::internal)]
+#![cfg_attr(bootstrap, feature(never_type))]
 #![doc(test(attr(allow(unused_variables), deny(warnings), allow(internal_features))))]
 #![feature(core_intrinsics)]
 #![feature(min_specialization)]
-#![feature(never_type)]
 #![feature(sized_hierarchy)]
 // tidy-alphabetical-end
 

compiler/rustc_trait_selection/src/lib.rs

@@ -11,13 +11,13 @@
 //! This API is completely unstable and subject to change.
 
 // tidy-alphabetical-start
+#![cfg_attr(bootstrap, feature(never_type))]
 #![feature(associated_type_defaults)]
 #![feature(box_patterns)]
 #![feature(default_field_values)]
 #![feature(hash_set_entry)]
 #![feature(iter_intersperse)]
 #![feature(iterator_try_reduce)]
-#![feature(never_type)]
 #![feature(strip_circumfix)]
 #![feature(try_blocks)]
 #![feature(unwrap_infallible)]

compiler/rustc_transmute/src/lib.rs

@@ -1,6 +1,6 @@
 // tidy-alphabetical-start
+#![cfg_attr(bootstrap, feature(never_type))]
 #![cfg_attr(test, feature(test))]
-#![feature(never_type)]
 // tidy-alphabetical-end
 
 pub(crate) use rustc_data_structures::fx::{FxIndexMap as Map, FxIndexSet as Set};

compiler/rustc_ty_utils/src/lib.rs

@@ -5,10 +5,10 @@
 //! This API is completely unstable and subject to change.
 
 // tidy-alphabetical-start
+#![cfg_attr(bootstrap, feature(never_type))]
 #![feature(associated_type_defaults)]
 #![feature(box_patterns)]
 #![feature(iterator_try_collect)]
-#![feature(never_type)]
 // tidy-alphabetical-end
 
 use rustc_middle::query::Providers;

library/alloc/src/lib.rs

@@ -184,7 +184,6 @@
 #![feature(min_specialization)]
 #![feature(multiple_supertrait_upcastable)]
 #![feature(negative_impls)]
-#![feature(never_type)]
 #![feature(optimize_attribute)]
 #![feature(rustc_attrs)]
 #![feature(slice_internals)]

library/alloctests/lib.rs

@@ -57,7 +57,6 @@
 #![feature(const_trait_impl)]
 #![feature(dropck_eyepatch)]
 #![feature(min_specialization)]
-#![feature(never_type)]
 #![feature(optimize_attribute)]
 #![feature(prelude_import)]
 #![feature(rustc_attrs)]

library/core/src/clone.rs

@@ -631,7 +631,7 @@ mod impls {
         bool char
     }
 
-    #[unstable(feature = "never_type", issue = "35121")]
+    #[stable(feature = "never_type", since = "CURRENT_RUSTC_VERSION")]
     #[rustc_const_unstable(feature = "const_clone", issue = "142757")]
     impl const Clone for ! {
         #[inline]

library/core/src/cmp.rs

@@ -2078,7 +2078,7 @@ mod impls {
 
     ord_impl! { char usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
 
-    #[unstable(feature = "never_type", issue = "35121")]
+    #[stable(feature = "never_type", since = "CURRENT_RUSTC_VERSION")]
     #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
     impl const PartialEq for ! {
         #[inline]
@@ -2087,11 +2087,11 @@ mod impls {
         }
     }
 
-    #[unstable(feature = "never_type", issue = "35121")]
+    #[stable(feature = "never_type", since = "CURRENT_RUSTC_VERSION")]
     #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
     impl const Eq for ! {}
 
-    #[unstable(feature = "never_type", issue = "35121")]
+    #[stable(feature = "never_type", since = "CURRENT_RUSTC_VERSION")]
     #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
     impl const PartialOrd for ! {
         #[inline]
@@ -2100,7 +2100,7 @@ mod impls {
         }
     }
 
-    #[unstable(feature = "never_type", issue = "35121")]
+    #[stable(feature = "never_type", since = "CURRENT_RUSTC_VERSION")]
     #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
     impl const Ord for ! {
         #[inline]