[NFC] [clang] simplify isDesignatorAtObjectEnd (llvm#126658)

IsLastOrInvalidFieldDecl would always return true if `Invalid=true`, so
we know that !IsLastOrInvalidFieldDecl(...) means !Invalid.

Author: fmayer

clang/lib/AST/ExprConstant.cpp

@@ -12536,10 +12536,9 @@ static const Expr *ignorePointerCastsAndParens(const Expr *E) {
 static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) {
   assert(!LVal.Designator.Invalid);
 
-  auto IsLastOrInvalidFieldDecl = [&Ctx](const FieldDecl *FD, bool &Invalid) {
+  auto IsLastOrInvalidFieldDecl = [&Ctx](const FieldDecl *FD) {
     const RecordDecl *Parent = FD->getParent();
-    Invalid = Parent->isInvalidDecl();
-    if (Invalid || Parent->isUnion())
+    if (Parent->isInvalidDecl() || Parent->isUnion())
       return true;
     const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(Parent);
     return FD->getFieldIndex() + 1 == Layout.getFieldCount();
@@ -12548,14 +12547,12 @@ static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) {
   auto &Base = LVal.getLValueBase();
   if (auto *ME = dyn_cast_or_null<MemberExpr>(Base.dyn_cast<const Expr *>())) {
     if (auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl())) {
-      bool Invalid;
-      if (!IsLastOrInvalidFieldDecl(FD, Invalid))
-        return Invalid;
+      if (!IsLastOrInvalidFieldDecl(FD))
+        return false;
     } else if (auto *IFD = dyn_cast<IndirectFieldDecl>(ME->getMemberDecl())) {
       for (auto *FD : IFD->chain()) {
-        bool Invalid;
-        if (!IsLastOrInvalidFieldDecl(cast<FieldDecl>(FD), Invalid))
-          return Invalid;
+        if (!IsLastOrInvalidFieldDecl(cast<FieldDecl>(FD)))
+          return false;
       }
     }
   }
@@ -12591,9 +12588,8 @@ static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) {
         return false;
       BaseType = CT->getElementType();
     } else if (auto *FD = getAsField(Entry)) {
-      bool Invalid;
-      if (!IsLastOrInvalidFieldDecl(FD, Invalid))
-        return Invalid;
+      if (!IsLastOrInvalidFieldDecl(FD))
+        return false;
       BaseType = FD->getType();
     } else {
       assert(getAsBaseClass(Entry) && "Expecting cast to a base class");