Avoid unnecessary interning in `Ident::from_str()` calls.

A lot of these static symbols are pre-interned.

2 files changed, 6 insertions, 5 deletions

diff --git a/src/libsyntax_ext/env.rs b/src/libsyntax_ext/env.rs
index ccff4aec2c8..2127179eecb 100644
--- a/src/libsyntax_ext/env.rs
+++ b/src/libsyntax_ext/env.rs
@@ -6,7 +6,7 @@
 use syntax::ast::{self, Ident, GenericArg};
 use syntax::ext::base::{self, *};
 use syntax::ext::build::AstBuilder;
-use syntax::symbol::{keywords, Symbol};
+use syntax::symbol::{keywords, Symbol, sym};
 use syntax_pos::Span;
 use syntax::tokenstream;
 
@@ -29,7 +29,8 @@ pub fn expand_option_env<'cx>(cx: &'cx mut ExtCtxt<'_>,
                                      true,
                                      cx.std_path(&["option", "Option", "None"]),
                                      vec![GenericArg::Type(cx.ty_rptr(sp,
-                                                     cx.ty_ident(sp, Ident::from_str("str")),
+                                                     cx.ty_ident(sp,
+                                                                 Ident::with_empty_ctxt(sym::str)),
                                                      Some(lt),
                                                      ast::Mutability::Immutable))],
                                      vec![]))
diff --git a/src/libsyntax_ext/proc_macro_decls.rs b/src/libsyntax_ext/proc_macro_decls.rs
index 1eab739cf64..c582fb422c9 100644
--- a/src/libsyntax_ext/proc_macro_decls.rs
+++ b/src/libsyntax_ext/proc_macro_decls.rs
@@ -362,11 +362,11 @@ fn mk_decls(
     });
     let span = DUMMY_SP.apply_mark(mark);
 
-    let hidden = cx.meta_list_item_word(span, Symbol::intern("hidden"));
-    let doc = cx.meta_list(span, Symbol::intern("doc"), vec![hidden]);
+    let hidden = cx.meta_list_item_word(span, sym::hidden);
+    let doc = cx.meta_list(span, sym::doc, vec![hidden]);
     let doc_hidden = cx.attribute(span, doc);
 
-    let proc_macro = Ident::from_str("proc_macro");
+    let proc_macro = Ident::with_empty_ctxt(sym::proc_macro);
     let krate = cx.item(span,
                         proc_macro,
                         Vec::new(),