Continue cfg syntax transition

All deprecation warnings have been converted to errors. This includes
the warning for multiple cfgs on one item. We'll leave that as an error
for some period of time to ensure that all uses are updated before the
behavior changes from "or" to "and".

src/libsyntax/ext/cfg.rs

@@ -8,11 +8,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-/**
-The compiler code necessary to support the cfg! extension, which
-expands to a literal `true` or `false` based on whether the given cfgs
-match the current compilation environment.
-*/
+/// The compiler code necessary to support the cfg! extension, which expands to
+/// a literal `true` or `false` based on whether the given cfg matches the
+/// current compilation environment.
 
 use ast;
 use codemap::Span;
@@ -24,28 +22,18 @@ use attr::*;
 use parse::attr::ParserAttr;
 use parse::token;
 
-
 pub fn expand_cfg<'cx>(cx: &mut ExtCtxt,
                        sp: Span,
                        tts: &[ast::TokenTree])
                        -> Box<base::MacResult+'static> {
     let mut p = cx.new_parser_from_tts(tts);
-    let mut cfgs = Vec::new();
-    // parse `cfg!(meta_item, meta_item(x,y), meta_item="foo", ...)`
-    while p.token != token::EOF {
-        cfgs.push(p.parse_meta_item());
-        if p.eat(&token::EOF) { break } // trailing comma is optional,.
-        p.expect(&token::COMMA);
+    let cfg = p.parse_meta_item();
+
+    if !p.eat(&token::EOF) {
+        cx.span_err(sp, "expected 1 cfg-pattern");
+        return DummyResult::expr(sp);
     }
 
-    if cfgs.len() != 1 {
-        cx.span_warn(sp, "The use of multiple cfgs at the top level of `cfg!` \
-                          is deprecated. Change `cfg!(a, b)` to \
-                          `cfg!(all(a, b))`.");
-    }
-
-    let matches_cfg = cfgs.iter().all(|cfg| attr::cfg_matches(&cx.parse_sess.span_diagnostic,
-                                                              cx.cfg.as_slice(), &**cfg));
-
+    let matches_cfg = attr::cfg_matches(&cx.parse_sess.span_diagnostic, cx.cfg.as_slice(), &*cfg);
     MacExpr::new(cx.expr_bool(sp, matches_cfg))
 }