Remove gensym from format_args

Author: matthewjasper

src/libcore/macros.rs

@@ -767,7 +767,6 @@ pub(crate) mod builtin {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[allow_internal_unstable(fmt_internals)]
     #[rustc_builtin_macro]
-    #[rustc_macro_transparency = "semitransparent"]
     pub macro format_args {
         ($fmt:expr) => ({ /* compiler built-in */ }),
         ($fmt:expr, $($args:tt)*) => ({ /* compiler built-in */ })
@@ -779,7 +778,6 @@ pub(crate) mod builtin {
                          language use and is subject to change")]
     #[allow_internal_unstable(fmt_internals)]
     #[rustc_builtin_macro]
-    #[rustc_macro_transparency = "semitransparent"]
     pub macro format_args_nl {
         ($fmt:expr) => ({ /* compiler built-in */ }),
         ($fmt:expr, $($args:tt)*) => ({ /* compiler built-in */ })

src/libsyntax_ext/format.rs

@@ -646,7 +646,7 @@ impl<'a, 'b> Context<'a, 'b> {
         let mut heads = Vec::with_capacity(self.args.len());
 
         let names_pos: Vec<_> = (0..self.args.len())
-            .map(|i| self.ecx.ident_of(&format!("arg{}", i)).gensym())
+            .map(|i| ast::Ident::from_str_and_span(&format!("arg{}", i), self.macsp))
             .collect();
 
         // First, build up the static array which will become our precompiled
@@ -843,7 +843,7 @@ pub fn expand_preparsed_format_args(
     let arg_unique_types: Vec<_> = (0..args.len()).map(|_| Vec::new()).collect();
 
     let mut macsp = ecx.call_site();
-    macsp = macsp.apply_mark(ecx.current_expansion.id);
+    macsp = macsp.with_ctxt(ecx.backtrace());
 
     let msg = "format argument must be a string literal";
     let fmt_sp = efmt.span;

src/test/ui/format-hygiene.rs

@@ -0,0 +1,12 @@
+// check-pass
+
+#![allow(non_upper_case_globals)]
+#![feature(format_args_nl)]
+
+static arg0: () = ();
+
+fn main() {
+    static arg1: () = ();
+    format_args!("{} {:?}", 0, 1);
+    format_args_nl!("{} {:?}", 0, 1);
+}