Auto merge of #155501 - WaffleLapkin:dont-reserve-from-never-type, r=<try>

[experiment][2] meow mrrrumph

Author: bors

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

@@ -618,8 +618,6 @@ 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]`.