[clang] Fix the incorrect dependence bits for DependentExtIntType.

[hokein]

Summary

The error-bit was missing, and the unexpandedpack bit seemed to be
set incorrectly.

[sammccall]

Existing logic is odd. Error propagation change is definitely correct, and I suspect the other change is too, but let's ask just in case.

(The whole DependentIntExtType landed after the dependence refactoring, so this wasn't something we mangled in the refactoring)

clang/lib/AST/Type.cpp

356

@erichkeane was there any intent behind translating "num bits contains unexpanded pack" into "extint is variably modified", or was this an oversight? (My guess is the latter, just want to double check)

[erichkeane]

clang/lib/AST/Type.cpp

356

Ah, I think this was a result of a messy/not completely understood rebase. The 'toTypeDependence' parts appeared in the middle of my review, so I must have just merged the change incorrectly.

This patch seems like the right thing. Thanks!

clang/lib/AST/Type.cpp

 
 ExtIntType::ExtIntType(bool IsUnsigned, unsigned NumBits)
     : Type(ExtInt, QualType{}, TypeDependence::None), IsUnsigned(IsUnsigned),
       NumBits(NumBits) {}
 
 DependentExtIntType::DependentExtIntType(const ASTContext &Context,
                                          bool IsUnsigned, Expr *NumBitsExpr)
     : Type(DependentExtInt, QualType{},
-           ((NumBitsExpr->isValueDependent() || NumBitsExpr->isTypeDependent())
-                ? TypeDependence::Dependent
-                : TypeDependence::None) |
-               (NumBitsExpr->isInstantiationDependent()
-                    ? TypeDependence::Instantiation
-                    : TypeDependence::None) |
-               (NumBitsExpr->containsUnexpandedParameterPack()
-                    ? TypeDependence::VariablyModified
-                    : TypeDependence::None)),
+           toTypeDependence(NumBitsExpr->getDependence())),
       Context(Context), ExprAndUnsigned(NumBitsExpr, IsUnsigned) {}
 
 bool DependentExtIntType::isUnsigned() const {
   return ExprAndUnsigned.getInt();
 }
 
 clang::Expr *DependentExtIntType::getNumBitsExpr() const {
   return ExprAndUnsigned.getPointer();

clang/test/Sema/invalid-bitwidth-expr.mm

auto func() {
   // error-bit should be propagated from TemplateArgument to NestNameSpecifier.
   class Base<decltype(Foo(T()))>::type C; // expected-error {{no matching function for call to 'Foo'}}
   return C;
 }
 struct Z {
   int X : func<int>(); // expected-note {{in instantiation of function template}}
 };
 constexpr int ssss = sizeof(Z);
+
+struct Z2 {
+  int X : sizeof(_ExtInt(invalid())); // expected-error {{use of undeclared identifier}}
+};
+constexpr int sssss = sizeof(Z2);