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

src/libsyntax_ext/asm.rs

@@ -11,7 +11,7 @@ use syntax::ext::base::{self, *};
 use syntax::feature_gate;
 use syntax::parse::{self, token};
 use syntax::ptr::P;
-use syntax::symbol::Symbol;
+use syntax::symbol::{Symbol, sym};
 use syntax::ast::AsmDialect;
 use syntax_pos::Span;
 use syntax::tokenstream;
@@ -47,7 +47,7 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt<'_>,
                        -> Box<dyn base::MacResult + 'cx> {
     if !cx.ecfg.enable_asm() {
         feature_gate::emit_feature_err(&cx.parse_sess,
-                                       "asm",
+                                       sym::asm,
                                        sp,
                                        feature_gate::GateIssue::Language,
                                        feature_gate::EXPLAIN_ASM);