Fix error recovery with in-class initializer.

Previously, for a field with an invalid in-class initializer, we
would create a CXXDefaultInitExpr referring to a null Expr*.
This is not a good idea.

llvm-svn: 185216

clang/lib/Sema/SemaDeclCXX.cpp

@@ -919,6 +919,9 @@ static void CheckConstexprCtorInitializer(Sema &SemaRef,
                                           FieldDecl *Field,
                                           llvm::SmallSet<Decl*, 16> &Inits,
                                           bool &Diagnosed) {
+  if (Field->isInvalidDecl())
+    return;
+
   if (Field->isUnnamedBitfield())
     return;
 
@@ -3236,6 +3239,8 @@ static bool isIncompleteOrZeroLengthArrayType(ASTContext &Context, QualType T) {
 static bool CollectFieldInitializer(Sema &SemaRef, BaseAndFieldInfo &Info,
                                     FieldDecl *Field, 
                                     IndirectFieldDecl *Indirect = 0) {
+  if (Field->isInvalidDecl())
+    return false;
 
   // Overwhelmingly common case: we have a direct initializer for this field.
   if (CXXCtorInitializer *Init = Info.AllBaseFields.lookup(Field))
@@ -3274,7 +3279,7 @@ static bool CollectFieldInitializer(Sema &SemaRef, BaseAndFieldInfo &Info,
   // Don't try to build an implicit initializer if there were semantic
   // errors in any of the initializers (and therefore we might be
   // missing some that the user actually wrote).
-  if (Info.AnyErrorsInInits || Field->isInvalidDecl())
+  if (Info.AnyErrorsInInits)
     return false;
 
   CXXCtorInitializer *Init = 0;

clang/test/SemaCXX/constant-expression-cxx11.cpp

@@ -1694,3 +1694,18 @@ namespace VirtualFromBase {
   constexpr X<S2> *q = const_cast<X<X<S2>>*>(&xxs2);
   static_assert(q->f() == sizeof(S2), "");
 }
+
+namespace ConstexprConstructorRecovery {
+  class X { 
+  public: 
+      enum E : short { 
+          headers = 0x1, 
+          middlefile = 0x2, 
+          choices = 0x4 
+      }; 
+      constexpr X() noexcept {}; 
+  protected: 
+      E val{0}; // expected-error {{cannot initialize a member subobject of type 'ConstexprConstructorRecovery::X::E' with an rvalue of type 'int'}}
+  }; 
+  constexpr X x{};
+}