rustc: Deterministically link upstream C libraries

src/librustc/back/link.rs

@@ -1487,15 +1487,24 @@ fn add_upstream_rust_crates(args: &mut Vec<~str>, sess: &Session,
 //    crate as well.
 //
 // The use case for this is a little subtle. In theory the native
-// dependencies of a crate a purely an implementation detail of the crate
+// dependencies of a crate are purely an implementation detail of the crate
 // itself, but the problem arises with generic and inlined functions. If a
 // generic function calls a native function, then the generic function must
 // be instantiated in the target crate, meaning that the native symbol must
 // also be resolved in the target crate.
 fn add_upstream_native_libraries(args: &mut Vec<~str>, sess: &Session) {
-    let cstore = &sess.cstore;
-    cstore.iter_crate_data(|cnum, _| {
-        let libs = csearch::get_native_libraries(cstore, cnum);
+    // Be sure to use a topological sorting of crates becuase there may be
+    // interdependencies between native libraries. When passing -nodefaultlibs,
+    // for example, almost all native libraries depend on libc, so we have to
+    // make sure that's all the way at the right (liblibc is near the base of
+    // the dependency chain).
+    //
+    // This passes RequireStatic, but the actual requirement doesn't matter,
+    // we're just getting an ordering of crate numbers, we're not worried about
+    // the paths.
+    let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
+    for (cnum, _) in crates.move_iter() {
+        let libs = csearch::get_native_libraries(&sess.cstore, cnum);
         for &(kind, ref lib) in libs.iter() {
             match kind {
                 cstore::NativeUnknown => args.push("-l" + *lib),
@@ -1508,5 +1517,5 @@ fn add_upstream_native_libraries(args: &mut Vec<~str>, sess: &Session) {
                 }
             }
         }
-    });
+    }
 }

src/test/run-make/interdependent-c-libraries/Makefile

@@ -0,0 +1,15 @@
+-include ../tools.mk
+
+# The rust crate foo will link to the native library foo, while the rust crate
+# bar will link to the native library bar. There is also a dependency between
+# the native library bar to the natibe library foo.
+#
+# This test ensures that the ordering of -lfoo and -lbar on the command line is
+# correct to complete the linkage. If passed as "-lfoo -lbar", then the 'foo'
+# library will be stripped out, and the linkage will fail.
+
+all: $(call STATICLIB,foo) $(call STATICLIB,bar)
+	$(RUSTC) foo.rs
+	$(RUSTC) bar.rs
+	$(RUSTC) main.rs -Z print-link-args
+

src/test/run-make/interdependent-c-libraries/bar.c

@@ -0,0 +1,3 @@
+void foo();
+
+void bar() { foo(); }

src/test/run-make/interdependent-c-libraries/bar.rs

@@ -0,0 +1,23 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![crate_type = "rlib"]
+
+extern crate foo;
+
+#[link(name = "bar")]
+extern {
+    fn bar();
+}
+
+pub fn doit() {
+    unsafe { bar(); }
+}
+

src/test/run-make/interdependent-c-libraries/foo.c

@@ -0,0 +1 @@
+void foo() {}

src/test/run-make/interdependent-c-libraries/foo.rs

@@ -0,0 +1,20 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![crate_type = "rlib"]
+
+#[link(name = "foo")]
+extern {
+    fn foo();
+}
+
+pub fn doit() {
+    unsafe { foo(); }
+}

src/test/run-make/interdependent-c-libraries/main.rs

@@ -0,0 +1,16 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+extern crate foo;
+extern crate bar;
+
+fn main() {
+    bar::doit();
+}