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

src/librustc_codegen_utils/lib.rs

@@ -23,6 +23,7 @@
 
 use rustc::ty::TyCtxt;
 use rustc::hir::def_id::LOCAL_CRATE;
+use syntax::symbol::sym;
 
 pub mod link;
 pub mod codegen_backend;
@@ -35,7 +36,7 @@
 /// reporting an error.
 pub fn check_for_rustc_errors_attr(tcx: TyCtxt<'_, '_, '_>) {
     if let Some((def_id, _)) = tcx.entry_fn(LOCAL_CRATE) {
-        if tcx.has_attr(def_id, "rustc_error") {
+        if tcx.has_attr(def_id, sym::rustc_error) {
             tcx.sess.span_fatal(tcx.def_span(def_id), "compilation successful");
         }
     }

src/librustc_codegen_utils/link.rs

@@ -2,6 +2,7 @@
 use rustc::session::Session;
 use std::path::{Path, PathBuf};
 use syntax::{ast, attr};
+use syntax::symbol::sym;
 use syntax_pos::Span;
 
 pub fn out_filename(sess: &Session,
@@ -49,7 +50,7 @@ pub fn find_crate_name(sess: Option<&Session>,
     // as used. After doing this, however, we still prioritize a crate name from
     // the command line over one found in the #[crate_name] attribute. If we
     // find both we ensure that they're the same later on as well.
-    let attr_crate_name = attr::find_by_name(attrs, "crate_name")
+    let attr_crate_name = attr::find_by_name(attrs, sym::crate_name)
         .and_then(|at| at.value_str().map(|s| (at, s)));
 
     if let Some(sess) = sess {

src/librustc_codegen_utils/symbol_names_test.rs

@@ -6,11 +6,11 @@
 
 use rustc::hir;
 use rustc::ty::TyCtxt;
-
 use rustc_mir::monomorphize::Instance;
+use syntax::symbol::{Symbol, sym};
 
-const SYMBOL_NAME: &'static str = "rustc_symbol_name";
-const DEF_PATH: &'static str = "rustc_def_path";
+const SYMBOL_NAME: Symbol = sym::rustc_symbol_name;
+const DEF_PATH: Symbol = sym::rustc_def_path;
 
 pub fn report_symbol_names<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) {
     // if the `rustc_attrs` feature is not enabled, then the