Introduce ast::proto_bare

Issue #1022

src/comp/metadata/tyencode.rs

@@ -197,6 +197,7 @@ fn enc_proto(w: io::writer, proto: proto) {
       proto_iter. { w.write_char('W'); }
       proto_fn. { w.write_char('F'); }
       proto_block. { w.write_char('B'); }
+      proto_bare. { w.write_char('R'); }
     }
 }
 

src/comp/middle/typeck.rs

@@ -478,7 +478,7 @@ mod write {
 // has iter type and block has block type. This may end up changing.
 fn proto_to_ty_proto(proto: ast::proto) -> ast::proto {
     ret alt proto {
-          ast::proto_iter. | ast::proto_block. { proto }
+          ast::proto_iter. | ast::proto_block. | ast::proto_bare. { proto }
           _ { ast::proto_fn }
         };
 }

src/comp/syntax/ast.rs

@@ -102,7 +102,15 @@ tag kind { kind_pinned; kind_shared; kind_unique; }
 
 tag _auth { auth_unsafe; }
 
-tag proto { proto_iter; proto_fn; proto_block; proto_closure; }
+tag proto {
+    proto_iter;
+    proto_fn;
+    proto_block;
+    proto_closure;
+    // Functions without an environment. Eventually, this will
+    // merge with proto_fn.
+    proto_bare;
+}
 
 tag binop {
     add;

src/comp/syntax/parse/parser.rs

@@ -2129,7 +2129,7 @@ fn parse_auth(p: parser) -> ast::_auth {
 fn parse_fn_proto(p: parser) -> ast::proto {
     if p.peek() == token::POUND {
         p.bump();
-        ast::proto_fn
+        ast::proto_bare
     } else {
         ast::proto_fn
     }

src/comp/syntax/print/pprust.rs

@@ -1643,6 +1643,7 @@ fn proto_to_str(p: ast::proto) -> str {
           ast::proto_iter. { "iter" }
           ast::proto_block. { "block" }
           ast::proto_closure. { "lambda" }
+          ast::proto_bare. { "fn#" }
         };
 }