Rollup merge of #62258 - petrochenkov:idclean, r=Centril

syntax: Unsupport `foo! bar { ... }` macros in the parser

Their support in expansion was removed in https://github.com/rust-lang/rust/pull/61606.

Also un-reserve `macro_rules` as a macro name, there's no ambiguity between `macro_rules` definitions and macro calls (it also wasn't reserved correctly).

cc https://github.com/rust-lang-nursery/wg-grammar/issues/51

1 files changed, 1 insertions, 4 deletions

diff --git a/src/librustc_plugin/registry.rs b/src/librustc_plugin/registry.rs
index 2fb65a60693..ec2855f826a 100644
--- a/src/librustc_plugin/registry.rs
+++ b/src/librustc_plugin/registry.rs
@@ -6,7 +6,7 @@ use rustc::util::nodemap::FxHashMap;
 
 use syntax::ext::base::{SyntaxExtension, SyntaxExtensionKind, NamedSyntaxExtension};
 use syntax::ext::base::MacroExpanderFn;
-use syntax::symbol::{Symbol, sym};
+use syntax::symbol::Symbol;
 use syntax::ast;
 use syntax::feature_gate::AttributeType;
 use syntax_pos::Span;
@@ -85,9 +85,6 @@ impl<'a> Registry<'a> {
     ///
     /// This is the most general hook into `libsyntax`'s expansion behavior.
     pub fn register_syntax_extension(&mut self, name: ast::Name, mut extension: SyntaxExtension) {
-        if name == sym::macro_rules {
-            panic!("user-defined macros may not be named `macro_rules`");
-        }
         if extension.def_info.is_none() {
             extension.def_info = Some((ast::CRATE_NODE_ID, self.krate_span));
         }