[clang][initlist] handle incomplete array type in Constant Expr Calculation (#155080)

fix: #151716

In #65918, support of incomplete array type is added in
TryReferenceListInitialization. It causes the crash in Constant Expr
Calculation since it only considers the case where it is
ConstantArrayType.

This patch wants to add support for incomplete array type also.

1 files changed, 8 insertions, 5 deletions

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 66362d4..f0592b0 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -4030,10 +4030,12 @@ findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
     LastField = nullptr;
     if (ObjType->isArrayType()) {
       // Next subobject is an array element.
-      const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
-      assert(CAT && "vla in literal type?");
+      const ArrayType *AT = Info.Ctx.getAsArrayType(ObjType);
+      assert((isa<ConstantArrayType>(AT) || isa<IncompleteArrayType>(AT)) &&
+             "vla in literal type?");
       uint64_t Index = Sub.Entries[I].getAsArrayIndex();
-      if (CAT->getSize().ule(Index)) {
+      if (const auto *CAT = dyn_cast<ConstantArrayType>(AT);
+          CAT && CAT->getSize().ule(Index)) {
         // Note, it should not be possible to form a pointer with a valid
         // designator which points more than one past the end of the array.
         if (Info.getLangOpts().CPlusPlus11)
@@ -4044,12 +4046,13 @@ findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
         return handler.failed();
       }
 
-      ObjType = CAT->getElementType();
+      ObjType = AT->getElementType();
 
       if (O->getArrayInitializedElts() > Index)
         O = &O->getArrayInitializedElt(Index);
       else if (!isRead(handler.AccessKind)) {
-        if (!CheckArraySize(Info, CAT, E->getExprLoc()))
+        if (const auto *CAT = dyn_cast<ConstantArrayType>(AT);
+            CAT && !CheckArraySize(Info, CAT, E->getExprLoc()))
           return handler.failed();
 
         expandArray(*O, Index);