rustc: Add a path attribute for crate directives

The path information was an optional "filename" component of crate
directive AST. It is now replaced by an attribute with metadata named
"path".

With this commit, a directive

  mod foo = "foo.rs";

should be written as:

  #[path = "foo.rs"]
  mod foo;

Closes issue #906.

src/comp/syntax/ast.rs

@@ -58,8 +58,8 @@ type crate_ =
      config: crate_cfg};
 
 tag crate_directive_ {
-    cdir_src_mod(ident, option::t<filename>, [attribute]);
-    cdir_dir_mod(ident, option::t<filename>, [@crate_directive], [attribute]);
+    cdir_src_mod(ident, [attribute]);
+    cdir_dir_mod(ident, [@crate_directive], [attribute]);
     cdir_view_item(@view_item);
     cdir_syntax(path);
 }

src/comp/syntax/fold.rs

@@ -159,11 +159,11 @@ fn noop_fold_crate(c: crate_, fld: ast_fold) -> crate_ {
 fn noop_fold_crate_directive(cd: crate_directive_, fld: ast_fold) ->
    crate_directive_ {
     ret alt cd {
-          cdir_src_mod(id, fname, attrs) {
-            cdir_src_mod(fld.fold_ident(id), fname, attrs)
+          cdir_src_mod(id, attrs) {
+            cdir_src_mod(fld.fold_ident(id), attrs)
           }
-          cdir_dir_mod(id, fname, cds, attrs) {
-            cdir_dir_mod(fld.fold_ident(id), fname,
+          cdir_dir_mod(id, cds, attrs) {
+            cdir_dir_mod(fld.fold_ident(id),
                          vec::map(fld.fold_crate_directive, cds), attrs)
           }
           cdir_view_item(vi) { cdir_view_item(fld.fold_view_item(vi)) }

src/comp/syntax/parse/eval.rs

@@ -1,4 +1,5 @@
 
+import front::attr;
 import std::{option, result, io, fs};
 import std::option::{some, none};
 import syntax::ast;
@@ -86,13 +87,21 @@ fn parse_companion_mod(cx: ctx, prefix: str, suffix: option::t<str>)
     }
 }
 
+fn cdir_path_opt(id: str, attrs: [ast::attribute]) -> str {
+    alt attr::get_meta_item_value_str_by_name(attrs, "path") {
+      some(d) {
+        ret d;
+      }
+      none. { ret id; }
+    }
+}
+
 fn eval_crate_directive(cx: ctx, cdir: @ast::crate_directive, prefix: str,
                         &view_items: [@ast::view_item],
                         &items: [@ast::item]) {
     alt cdir.node {
-      ast::cdir_src_mod(id, file_opt, attrs) {
-        let file_path = id + ".rs";
-        alt file_opt { some(f) { file_path = f; } none. { } }
+      ast::cdir_src_mod(id, attrs) {
+        let file_path = cdir_path_opt(id + ".rs", attrs);
         let full_path =
             if std::fs::path_is_absolute(file_path) {
                 file_path
@@ -113,9 +122,8 @@ fn eval_crate_directive(cx: ctx, cdir: @ast::crate_directive, prefix: str,
         cx.byte_pos = p0.get_byte_pos();
         items += [i];
       }
-      ast::cdir_dir_mod(id, dir_opt, cdirs, attrs) {
-        let path = id;
-        alt dir_opt { some(d) { path = d; } none. { } }
+      ast::cdir_dir_mod(id, cdirs, attrs) {
+        let path = cdir_path_opt(id, attrs);
         let full_path =
             if std::fs::path_is_absolute(path) {
                 path

src/comp/syntax/parse/parser.rs

@@ -2475,19 +2475,12 @@ fn parse_crate_directive(p: parser, first_outer_attr: [ast::attribute]) ->
     if expect_mod || is_word(p, "mod") {
         expect_word(p, "mod");
         let id = parse_ident(p);
-        let file_opt =
-            alt p.peek() {
-              token::EQ. { p.bump(); some(parse_str(p)) }
-              _ {
-                attr::get_meta_item_value_str_by_name(outer_attrs, "path")
-              }
-            };
         alt p.peek() {
           // mod x = "foo.rs";
           token::SEMI. {
             let hi = p.get_hi_pos();
             p.bump();
-            ret spanned(lo, hi, ast::cdir_src_mod(id, file_opt, outer_attrs));
+            ret spanned(lo, hi, ast::cdir_src_mod(id, outer_attrs));
           }
           // mod x = "foo_dir" { ...directives... }
           token::LBRACE. {
@@ -2500,7 +2493,7 @@ fn parse_crate_directive(p: parser, first_outer_attr: [ast::attribute]) ->
             let hi = p.get_hi_pos();
             expect(p, token::RBRACE);
             ret spanned(lo, hi,
-                        ast::cdir_dir_mod(id, file_opt, cdirs, mod_attrs));
+                        ast::cdir_dir_mod(id, cdirs, mod_attrs));
           }
           t { unexpected(p, t); }
         }

src/comp/syntax/visit.rs

@@ -56,8 +56,8 @@ fn visit_crate<E>(c: crate, e: E, v: vt<E>) {
 
 fn visit_crate_directive<E>(cd: @crate_directive, e: E, v: vt<E>) {
     alt cd.node {
-      cdir_src_mod(_, _, _) { }
-      cdir_dir_mod(_, _, cdirs, _) {
+      cdir_src_mod(_, _) { }
+      cdir_dir_mod(_, cdirs, _) {
         for cdir: @crate_directive in cdirs {
             visit_crate_directive(cdir, e, v);
         }