rustc: Add a next_ann method to ext_ctxt

After this we can remove the parser from the syntax extensions, at least for
now.

src/comp/front/ext.rs

@@ -2,6 +2,7 @@ import std::option;
 import std::map::hashmap;
 
 import driver::session::session;
+import front::parser::parser;
 import util::common::span;
 import util::common::new_str_hash;
 
@@ -24,13 +25,17 @@ fn syntax_expander_table() -> hashmap[str, syntax_extension] {
 }
 
 type span_msg_fn = fn (span sp, str msg) -> !;
+type next_ann_fn = fn () -> ast::ann;
 
 // Provides a limited set of services necessary for syntax extensions
 // to do their thing
 type ext_ctxt = rec(span_msg_fn span_err,
-                    span_msg_fn span_unimpl);
+                    span_msg_fn span_unimpl,
+                    next_ann_fn next_ann);
+
+fn mk_ctxt(parser parser) -> ext_ctxt {
+    auto sess = parser.get_session();
 
-fn mk_ctxt(session sess) -> ext_ctxt {
     fn ext_span_err_(session sess, span sp, str msg) -> ! {
         sess.span_err(sp, msg);
     }
@@ -41,8 +46,12 @@ fn mk_ctxt(session sess) -> ext_ctxt {
     }
     auto ext_span_unimpl = bind ext_span_unimpl_(sess, _, _);
 
+    fn ext_next_ann_(parser parser) -> ast::ann { parser.get_ann() }
+    auto ext_next_ann = bind ext_next_ann_(parser);
+
     ret rec(span_err = ext_span_err,
-            span_unimpl = ext_span_unimpl);
+            span_unimpl = ext_span_unimpl,
+            next_ann = ext_next_ann);
 }
 
 //

src/comp/front/parser.rs

@@ -1048,7 +1048,7 @@ fn expand_syntax_ext(&parser p, common::span sp,
             p.err("unknown syntax expander: '" + extname + "'");
         }
         case (some(ext::x(?ext))) {
-            auto ext_cx = ext::mk_ctxt(p.get_session());
+            auto ext_cx = ext::mk_ctxt(p);
             ret ast::expr_ext(path, args, body,
                               ext(ext_cx, p, sp, args, body), 
                               p.get_ann());