rustc: Use link_name attribute for native function

Fixes issue #906

src/comp/front/attr.rs

@@ -17,6 +17,7 @@ export require_unique_names;
 export get_attr_name;
 export get_meta_item_name;
 export get_meta_item_value_str;
+export get_meta_item_value_str_by_name;
 export get_meta_item_list;
 export mk_name_value_item_str;
 export mk_name_value_item;
@@ -85,6 +86,15 @@ fn get_meta_item_value_str(meta: @ast::meta_item) -> option::t<str> {
     }
 }
 
+fn get_meta_item_value_str_by_name(attrs: [ast::attribute], name: ast::ident)
+    -> option::t<str> {
+    let mattrs = find_attrs_by_name(attrs, name);
+    if vec::len(mattrs) > 0u {
+        ret get_meta_item_value_str(attr_meta(mattrs[0]));
+    }
+    ret option::none;
+}
+
 fn get_meta_item_list(meta: @ast::meta_item) -> option::t<[@ast::meta_item]> {
     alt meta.node {
       ast::meta_list(_, l) { option::some(l) }

src/comp/metadata/encoder.rs

@@ -348,7 +348,7 @@ fn encode_info_for_native_item(ecx: @encode_ctxt, ebml_w: ebml::writer,
         encode_type(ecx, ebml_w,
                     ty::mk_native(ecx.ccx.tcx, local_def(nitem.id)));
       }
-      native_item_fn(_, fn_decl, tps) {
+      native_item_fn(fn_decl, tps) {
         let letter =
             alt fn_decl.purity {
               unsafe_fn. { 'U' }

src/comp/middle/resolve.rs

@@ -656,7 +656,7 @@ fn lookup_in_scope(e: env, sc: scopes, sp: span, name: ident, ns: namespace)
           }
           scope_native_item(it) {
             alt it.node {
-              ast::native_item_fn(_, decl, ty_params) {
+              ast::native_item_fn(decl, ty_params) {
                 ret lookup_in_fn(name, decl, ty_params, ns);
               }
             }
@@ -1077,7 +1077,7 @@ fn lookup_in_mie(e: env, mie: mod_index_entry, ns: namespace) ->
                 ret some(ast::def_native_ty(local_def(native_item.id)));
             }
           }
-          ast::native_item_fn(_, decl, _) {
+          ast::native_item_fn(decl, _) {
             if ns == ns_value {
                 ret some(ast::def_native_fn(
                     local_def(native_item.id),

src/comp/middle/trans.rs

@@ -17,6 +17,7 @@ import std::map::hashmap;
 import std::map::{new_int_hash, new_str_hash};
 import std::option::{some, none};
 import driver::session;
+import front::attr;
 import middle::{ty, gc};
 import middle::freevars::*;
 import back::{link, abi, upcall};
@@ -5585,7 +5586,7 @@ fn native_fn_ty_param_count(cx: @crate_ctxt, id: ast::node_id) -> uint {
         cx.sess.bug("register_native_fn(): native fn isn't \
                         actually a fn");
       }
-      ast::native_item_fn(_, _, tps) {
+      ast::native_item_fn(_, tps) {
         count = std::vec::len::<ast::ty_param>(tps);
       }
     }
@@ -5805,14 +5806,13 @@ fn item_path(item: @ast::item) -> [str] { ret [item.ident]; }
 fn collect_native_item(ccx: @crate_ctxt, i: @ast::native_item, &&pt: [str],
                        _v: vt<[str]>) {
     alt i.node {
-      ast::native_item_fn(link_name, _, _) {
+      ast::native_item_fn(_, _) {
         if !ccx.obj_methods.contains_key(i.id) {
-            let name =
-              if option::is_some(link_name) {
-                option::get(link_name)
-              } else {
-                i.ident
-              };
+            let name = i.ident;
+            alt attr::get_meta_item_value_str_by_name(i.attrs, "link_name") {
+              none. { }
+              option::some(ln) { name = ln; }
+            }
             register_native_fn(ccx, i.span, pt, name, i.id);
         }
       }

src/comp/middle/typeck.rs

@@ -668,7 +668,7 @@ mod collect {
                          abi: ast::native_abi) -> ty::ty_param_kinds_and_ty {
         let no_kinds: [ast::kind] = [];
         alt it.node {
-          ast::native_item_fn(_, fn_decl, params) {
+          ast::native_item_fn(fn_decl, params) {
             let get = bind getter(cx, _);
             let convert = bind ast_ty_to_ty(cx.tcx, get, _);
             let f = bind ty_of_arg(cx, _);
@@ -819,7 +819,7 @@ mod collect {
           ast::native_item_ty. {
             // FIXME: Native types have no annotation. Should they? --pcw
           }
-          ast::native_item_fn(_, _, _) {
+          ast::native_item_fn(_, _) {
             write::ty_only(cx.tcx, i.id, tpt.ty);
           }
         }

src/comp/syntax/ast.rs

@@ -501,7 +501,7 @@ type native_item =
 
 tag native_item_ {
     native_item_ty;
-    native_item_fn(option::t<str>, fn_decl, [ty_param]);
+    native_item_fn(fn_decl, [ty_param]);
 }
 
 //

src/comp/syntax/fold.rs

@@ -187,9 +187,8 @@ fn noop_fold_native_item(&&ni: @native_item, fld: ast_fold) -> @native_item {
           node:
               alt ni.node {
                 native_item_ty. { native_item_ty }
-                native_item_fn(st, fdec, typms) {
-                  native_item_fn(st,
-                                 {inputs: vec::map(fold_arg, fdec.inputs),
+                native_item_fn(fdec, typms) {
+                  native_item_fn({inputs: vec::map(fold_arg, fdec.inputs),
                                   output: fld.fold_ty(fdec.output),
                                   purity: fdec.purity,
                                   il: fdec.il,

src/comp/syntax/parse/parser.rs

@@ -1956,13 +1956,11 @@ fn parse_item_native_fn(p: parser, attrs: [ast::attribute],
     let lo = p.get_last_lo_pos();
     let t = parse_fn_header(p);
     let decl = parse_fn_decl(p, purity, ast::il_normal);
-    let link_name = none;
-    if p.peek() == token::EQ { p.bump(); link_name = some(parse_str(p)); }
     let hi = p.get_hi_pos();
     expect(p, token::SEMI);
     ret @{ident: t.ident,
           attrs: attrs,
-          node: ast::native_item_fn(link_name, decl, t.tps),
+          node: ast::native_item_fn(decl, t.tps),
           id: p.get_id(),
           span: ast_util::mk_sp(lo, hi)};
 }

src/comp/syntax/print/pprust.rs

@@ -350,13 +350,9 @@ fn print_native_item(s: ps, item: @ast::native_item) {
 
 
 
-      ast::native_item_fn(lname, decl, typarams) {
+      ast::native_item_fn(decl, typarams) {
         print_fn(s, decl, ast::proto_bare, item.ident, typarams,
                  decl.constraints);
-        alt lname {
-          none. { }
-          some(ss) { space(s.s); word_space(s, "="); print_string(s, ss); }
-        }
         end(s); // end head-ibox
         word(s.s, ";");
         end(s); // end the outer fn box

src/comp/syntax/visit.rs

@@ -179,7 +179,7 @@ fn visit_pat<E>(p: @pat, e: E, v: vt<E>) {
 
 fn visit_native_item<E>(ni: @native_item, e: E, v: vt<E>) {
     alt ni.node {
-      native_item_fn(_, fd, _) { visit_fn_decl(fd, e, v); }
+      native_item_fn(fd, _) { visit_fn_decl(fd, e, v); }
       native_item_ty. { }
     }
 }

src/lib/win32_os.rs

@@ -4,8 +4,10 @@ native "cdecl" mod libc = "" {
     fn write(fd: int, buf: *u8, count: uint) -> int;
     fn fread(buf: *u8, size: uint, n: uint, f: libc::FILE) -> uint;
     fn fwrite(buf: *u8, size: uint, n: uint, f: libc::FILE) -> uint;
-    fn open(s: str::sbuf, flags: int, mode: uint) -> int = "_open";
-    fn close(fd: int) -> int = "_close";
+    #[link_name = "_open"]
+    fn open(s: str::sbuf, flags: int, mode: uint) -> int;
+    #[link_name = "_close"]
+    fn close(fd: int) -> int;
     type FILE;
     fn fopen(path: str::sbuf, mode: str::sbuf) -> FILE;
     fn _fdopen(fd: int, mode: str::sbuf) -> FILE;

src/test/run-pass/native-fn-linkname.rs

@@ -4,7 +4,8 @@ import std::vec;
 import std::str;
 
 native "cdecl" mod libc = "" {
-    fn my_strlen(str: *u8) -> uint = "strlen";
+    #[link_name = "strlen"]
+    fn my_strlen(str: *u8) -> uint;
 }
 
 fn strlen(str: str) -> uint unsafe {