Pass a Symbol to check_name, emit_feature_err, and related functions.

src/libsyntax_ext/global_asm.rs

@@ -16,12 +16,12 @@ use syntax::ext::base::{self, *};
 use syntax::feature_gate;
 use syntax::parse::token;
 use syntax::ptr::P;
-use syntax::symbol::Symbol;
+use syntax::symbol::{Symbol, sym};
 use syntax_pos::Span;
 use syntax::tokenstream;
 use smallvec::smallvec;
 
-pub const MACRO: &str = "global_asm";
+pub const MACRO: Symbol = sym::global_asm;
 
 pub fn expand_global_asm<'cx>(cx: &'cx mut ExtCtxt<'_>,
                               sp: Span,