auto merge of #11073 : klutzy/rust/issue-10978, r=alexcrichton

This patchset fixes small glitches which caused #10978.

src/etc/mklldeps.py

@@ -7,6 +7,7 @@ import subprocess
 f = open(sys.argv[1], 'wb')
 
 components = sys.argv[2].split(' ')
+components = [i for i in components if i]  # ignore extra whitespaces
 
 f.write("""// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
@@ -51,6 +52,10 @@ for llconfig in sys.argv[3:]:
     proc = subprocess.Popen(args, stdout = subprocess.PIPE)
     out, err = proc.communicate()
 
+    if err:
+        print("failed to run llconfig: args = `{}`".format(args))
+        sys.exit(1)
+
     for lib in out.strip().split(' '):
         lib = lib[2:] # chop of the leading '-l'
         f.write("#[link(name = \"" + lib + "\", kind = \"static\")]\n")

src/librustc/metadata/creader.rs

@@ -219,7 +219,11 @@ fn visit_item(e: &Env, i: @ast::item) {
                                 @"foo"
                             }
                         };
-                        cstore::add_used_library(cstore, n.to_owned(), kind);
+                        if n.is_empty() {
+                            e.sess.span_err(m.span, "#[link(name = \"\")] given with empty name");
+                        } else {
+                            cstore::add_used_library(cstore, n.to_owned(), kind);
+                        }
                     }
                     None => {}
                 }

src/test/compile-fail/bad-extern-link-attrs.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 
 #[link()] //~ ERROR: specified without `name =
+#[link(name = "")] //~ ERROR: with empty name
 #[link(name = "foo")]
 #[link(name = "foo", kind = "bar")] //~ ERROR: unknown kind
 extern {}