[Sema] Make an assertion stricter.

We now check for the exact range of IdealIndex.

llvm-svn: 242652
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index c28b9ce..f20ece5 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -4138,7 +4138,7 @@
         if (InitKey == IdealInitKeys[IdealIndex])
           break;
 
-      assert(IdealIndex != NumIdealInits &&
+      assert(IdealIndex >= 0 && IdealIndex < NumIdealInits &&
              "initializer not found in initializer list");
     }