Fix order of evaluation.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@60160 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Basic/Diagnostic.cpp b/lib/Basic/Diagnostic.cpp
index 8547ef4..88532a7 100644
--- a/lib/Basic/Diagnostic.cpp
+++ b/lib/Basic/Diagnostic.cpp
@@ -354,7 +354,7 @@
       if (TestPluralRange(ValMod, Start, End))
         return true;
     } else {
-      assert(C == '[' || (C >= '0' && C <= '9') &&
+      assert((C == '[' || (C >= '0' && C <= '9')) &&
              "Bad plural expression syntax: unexpected character");
       // Range expression
       if (TestPluralRange(ValNo, Start, End))