Remember the library files we used in rustc and pass them to the "linker".

This avoid the hardcoded -lstd, allows programs to use other crates and avoids
any differences that may exist in the rustc and ld search logic.

Author: cixtor

src/comp/driver/rustc.rs

@@ -271,7 +271,7 @@ fn build_session(@session::options sopts) -> session::session {
     auto crate_cache = common::new_int_hash[session::crate_metadata]();
     auto target_crate_num = 0;
     auto sess =
-        session::session(target_crate_num, target_cfg, sopts, crate_cache,
+        session::session(target_crate_num, target_cfg, sopts, crate_cache, [],
                          front::codemap::new_codemap(), 0u);
     ret sess;
 }
@@ -417,10 +417,13 @@ fn main(vec[str] args) {
                 gcc_args = common_args;
             }
         }
+
+        gcc_args += sess.get_used_libraries();
+
         if (sopts.shared) {
             gcc_args += [shared_cmd];
         } else {
-            gcc_args += ["-Lrustllvm", "-lrustllvm", "-lstd", "-lm", main];
+            gcc_args += ["-Lrustllvm", "-lrustllvm", "-lm", main];
         }
         // We run 'gcc' here
 

src/comp/driver/session.rs

@@ -66,6 +66,7 @@ obj session(ast::crate_num cnum,
             @config targ_cfg,
             @options opts,
             map::hashmap[int, crate_metadata] crates,
+            mutable vec[str] used_libraries,
             codemap::codemap cm,
             mutable uint err_count) {
     fn get_targ_cfg() -> @config { ret targ_cfg; }
@@ -122,6 +123,19 @@ obj session(ast::crate_num cnum,
         crates.insert(num, metadata);
     }
     fn has_external_crate(int num) -> bool { ret crates.contains_key(num); }
+    fn add_used_library(&str lib) {
+        // A program has a small number of libraries, so a vector is probably a
+        // good data structure in here.
+        for (str l in used_libraries) {
+            if (l == lib) {
+                ret;
+            }
+        }
+        used_libraries += [lib];
+    }
+    fn get_used_libraries() -> vec[str] {
+       ret used_libraries;
+    }
     fn get_codemap() -> codemap::codemap { ret cm; }
     fn lookup_pos(uint pos) -> codemap::loc {
         ret codemap::lookup_pos(cm, pos);

src/comp/front/creader.rs

@@ -582,12 +582,13 @@ fn find_library_crate(&session::session sess, &ast::ident ident,
     ret none;
 }
 
-fn load_library_crate(&session::session sess, &int cnum, &ast::ident ident,
+fn load_library_crate(&session::session sess, int cnum, &ast::ident ident,
                       &vec[@ast::meta_item] metas,
                       &vec[str] library_search_paths) {
     alt (find_library_crate(sess, ident, metas, library_search_paths)) {
         case (some(?t)) {
             sess.set_external_crate(cnum, rec(name=ident, data=t._1));
+            sess.add_used_library(t._0);
             ret;
         }
         case (_) { }