Rollup merge of #62735 - petrochenkov:galloc, r=alexcrichton

Turn `#[global_allocator]` into a regular attribute macro

It was a 99% macro with exception of some diagnostic details.

As a result of the change, `#[global_allocator]` now works in nested modules and even in nameless blocks.

Fixes https://github.com/rust-lang/rust/issues/44113
Fixes https://github.com/rust-lang/rust/issues/58072

1 files changed, 7 insertions, 0 deletions

diff --git a/src/libsyntax_ext/lib.rs b/src/libsyntax_ext/lib.rs
index 7de90278ed7..400bfe796bb 100644
--- a/src/libsyntax_ext/lib.rs
+++ b/src/libsyntax_ext/lib.rs
@@ -29,6 +29,7 @@ mod concat_idents;
 mod env;
 mod format;
 mod format_foreign;
+mod global_allocator;
 mod global_asm;
 mod log_syntax;
 mod proc_macro_server;
@@ -151,6 +152,12 @@ pub fn register_builtins(resolver: &mut dyn syntax::ext::base::Resolver,
             SyntaxExtensionKind::LegacyAttr(Box::new(test::expand_bench)), edition
         )
     });
+    register(sym::global_allocator, SyntaxExtension {
+        allow_internal_unstable: Some([sym::rustc_attrs][..].into()),
+        ..SyntaxExtension::default(
+            SyntaxExtensionKind::LegacyAttr(Box::new(global_allocator::expand)), edition
+        )
+    });
 
     let allow_internal_unstable = Some([sym::fmt_internals][..].into());
     register(sym::format_args, SyntaxExtension {