[driver] Add a warning for when -mcpu= is specified without an argument.  There
are likely many other OPT_xxxx_EQ options that could/should be added here.
rdar://10704648

llvm-svn: 151174
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index f9e5d82..0695317 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -113,6 +113,12 @@
       Diag(clang::diag::err_drv_unsupported_opt) << A->getAsString(*Args);
       continue;
     }
+
+    // Warn about -mcpu= without an argument.
+    if (A->getOption().matches(options::OPT_mcpu_EQ) && 
+        A->containsValue("")) {
+      Diag(clang::diag::warn_drv_empty_joined_argument) << A->getAsString(*Args);
+    }
   }
 
   return Args;