feature gate `cfg(target_feature)`.

This is theoretically a breaking change, but GitHub search turns up no
uses of it, and most non-built-in cfg's are passed via cargo features,
which look like `feature = "..."`, and hence can't overlap.

3 files changed, 15 insertions, 8 deletions

diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index d4b5e67eeb4..ef11a2bd66e 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -17,6 +17,7 @@ use codemap::{CodeMap, Span, ExpnId, ExpnInfo, NO_EXPANSION, CompilerExpansion};
 use ext;
 use ext::expand;
 use ext::tt::macro_rules;
+use feature_gate::GatedCfg;
 use parse;
 use parse::parser;
 use parse::token;
@@ -632,6 +633,7 @@ pub struct ExtCtxt<'a> {
     pub backtrace: ExpnId,
     pub ecfg: expand::ExpansionConfig<'a>,
     pub crate_root: Option<&'static str>,
+    pub feature_gated_cfgs: &'a mut Vec<GatedCfg>,
 
     pub mod_path: Vec<ast::Ident> ,
     pub exported_macros: Vec<ast::MacroDef>,
@@ -642,7 +644,8 @@ pub struct ExtCtxt<'a> {
 
 impl<'a> ExtCtxt<'a> {
     pub fn new(parse_sess: &'a parse::ParseSess, cfg: ast::CrateConfig,
-               ecfg: expand::ExpansionConfig<'a>) -> ExtCtxt<'a> {
+               ecfg: expand::ExpansionConfig<'a>,
+               feature_gated_cfgs: &'a mut Vec<GatedCfg>) -> ExtCtxt<'a> {
         let env = initial_syntax_expander_table(&ecfg);
         ExtCtxt {
             parse_sess: parse_sess,
@@ -651,6 +654,7 @@ impl<'a> ExtCtxt<'a> {
             mod_path: Vec::new(),
             ecfg: ecfg,
             crate_root: None,
+            feature_gated_cfgs: feature_gated_cfgs,
             exported_macros: Vec::new(),
             syntax_env: env,
             recursion_count: 0,
diff --git a/src/libsyntax/ext/cfg.rs b/src/libsyntax/ext/cfg.rs
index 8af7fb7b268..aa654e30530 100644
--- a/src/libsyntax/ext/cfg.rs
+++ b/src/libsyntax/ext/cfg.rs
@@ -34,6 +34,7 @@ pub fn expand_cfg<'cx>(cx: &mut ExtCtxt,
         return DummyResult::expr(sp);
     }
 
-    let matches_cfg = attr::cfg_matches(&cx.parse_sess.span_diagnostic, &cx.cfg, &*cfg);
+    let matches_cfg = attr::cfg_matches(&cx.parse_sess.span_diagnostic, &cx.cfg, &*cfg,
+                                        cx.feature_gated_cfgs);
     MacEager::expr(cx.expr_bool(sp, matches_cfg))
 }
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index e61a0b5401e..4f89b3494d4 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -21,7 +21,7 @@ use attr::AttrMetaMethods;
 use codemap;
 use codemap::{Span, Spanned, ExpnInfo, NameAndSpan, MacroBang, MacroAttribute, CompilerExpansion};
 use ext::base::*;
-use feature_gate::{self, Features};
+use feature_gate::{self, Features, GatedCfg};
 use fold;
 use fold::*;
 use parse;
@@ -1687,8 +1687,10 @@ pub fn expand_crate<'feat>(parse_sess: &parse::ParseSess,
                            // these are the macros being imported to this crate:
                            imported_macros: Vec<ast::MacroDef>,
                            user_exts: Vec<NamedSyntaxExtension>,
+                           feature_gated_cfgs: &mut Vec<GatedCfg>,
                            c: Crate) -> Crate {
-    let mut cx = ExtCtxt::new(parse_sess, c.config.clone(), cfg);
+    let mut cx = ExtCtxt::new(parse_sess, c.config.clone(), cfg,
+                              feature_gated_cfgs);
     if std_inject::no_core(&c) {
         cx.crate_root = None;
     } else if std_inject::no_std(&c) {
@@ -1878,7 +1880,7 @@ mod tests {
             src,
             Vec::new(), &sess);
         // should fail:
-        expand_crate(&sess,test_ecfg(),vec!(),vec!(),crate_ast);
+        expand_crate(&sess,test_ecfg(),vec!(),vec!(), &mut vec![], crate_ast);
     }
 
     // make sure that macros can't escape modules
@@ -1891,7 +1893,7 @@ mod tests {
             "<test>".to_string(),
             src,
             Vec::new(), &sess);
-        expand_crate(&sess,test_ecfg(),vec!(),vec!(),crate_ast);
+        expand_crate(&sess,test_ecfg(),vec!(),vec!(), &mut vec![], crate_ast);
     }
 
     // macro_use modules should allow macros to escape
@@ -1903,14 +1905,14 @@ mod tests {
             "<test>".to_string(),
             src,
             Vec::new(), &sess);
-        expand_crate(&sess, test_ecfg(), vec!(), vec!(), crate_ast);
+        expand_crate(&sess, test_ecfg(), vec!(), vec!(), &mut vec![], crate_ast);
     }
 
     fn expand_crate_str(crate_str: String) -> ast::Crate {
         let ps = parse::ParseSess::new();
         let crate_ast = panictry!(string_to_parser(&ps, crate_str).parse_crate_mod());
         // the cfg argument actually does matter, here...
-        expand_crate(&ps,test_ecfg(),vec!(),vec!(),crate_ast)
+        expand_crate(&ps,test_ecfg(),vec!(),vec!(), &mut vec![], crate_ast)
     }
 
     // find the pat_ident paths in a crate