Fix crash on invalid initialization with std::initializer_list

It is possible for CheckListElementTypes to fail without filling in any
initializer list elements.

llvm-svn: 255176

clang/lib/Sema/SemaInit.cpp

@@ -805,7 +805,8 @@ void InitListChecker::CheckImplicitInitList(const InitializedEntity &Entity,
     unsigned EndIndex = (Index == StartIndex? StartIndex : Index - 1);
     // Update the structured sub-object initializer so that it's ending
     // range corresponds with the end of the last initializer it used.
-    if (EndIndex < ParentIList->getNumInits()) {
+    if (EndIndex < ParentIList->getNumInits() &&
+        ParentIList->getInit(EndIndex)) {
       SourceLocation EndLoc
         = ParentIList->getInit(EndIndex)->getSourceRange().getEnd();
       StructuredSubobjectInitList->setRBraceLoc(EndLoc);