Don't ICE if an archive isn't actually an archive

src/librustc_trans/back/archive.rs

@@ -145,10 +145,13 @@ impl<'a> ArchiveBuilder<'a> {
 
     /// Adds all of the contents of a native library to this archive. This will
     /// search in the relevant locations for a library named `name`.
-    pub fn add_native_library(&mut self, name: &str) -> io::Result<()> {
+    pub fn add_native_library(&mut self, name: &str) {
         let location = find_library(name, &self.config.lib_search_paths,
                                     self.config.sess);
-        self.add_archive(&location, name, |_| false)
+        self.add_archive(&location, name, |_| false).unwrap_or_else(|e| {
+            self.config.sess.fatal(&format!("failed to add native library {}: {}",
+                                            location.to_string_lossy(), e));
+        });
     }
 
     /// Adds all of the contents of the rlib at the specified path to this

src/librustc_trans/back/link.rs

@@ -616,7 +616,7 @@ fn link_rlib<'a>(sess: &'a Session,
 
     for &(ref l, kind) in sess.cstore.get_used_libraries().borrow().iter() {
         match kind {
-            cstore::NativeStatic => ab.add_native_library(&l).unwrap(),
+            cstore::NativeStatic => ab.add_native_library(&l),
             cstore::NativeFramework | cstore::NativeUnknown => {}
         }
     }
@@ -792,7 +792,7 @@ fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
         ab.build();
     }
     if !sess.target.target.options.no_compiler_rt {
-        ab.add_native_library("compiler-rt").unwrap();
+        ab.add_native_library("compiler-rt");
     }
 
     let mut all_native_libs = vec![];

src/test/run-make/invalid-staticlib/Makefile

@@ -0,0 +1,5 @@
+-include ../tools.mk
+
+all:
+	touch $(TMPDIR)/libfoo.a
+	echo | $(RUSTC) - --crate-type=rlib -lstatic=foo 2>&1 | grep "failed to add native library"