[AST] Fix a crash on invalid bitwidth exprs when preserving the recoveryexprs.

[hokein]

Summary

If the bitwith expr contains errors, we mark the field decl invalid.

This patch also tweaks the behavior of ObjCInterfaceDecl to be consistent with
existing RecordDecl -- getObjCLayout method is only called with valid decls.

[sammccall]

clang/lib/AST/ASTContext.cpp

2165

these numbers are arbitrary AFAICT, this seems fine.

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

2

you might consider merging both tests into this file

[hokein]

address comments.

clang/lib/AST/ASTContext.cpp

#include "clang/Basic/AArch64SVEACLETypes.def"
   }
   case Type::ObjCObject:
     return getTypeInfo(cast<ObjCObjectType>(T)->getBaseType().getTypePtr());
   case Type::Adjusted:
   case Type::Decayed:
     return getTypeInfo(cast<AdjustedType>(T)->getAdjustedType().getTypePtr());
   case Type::ObjCInterface: {
     const auto *ObjCI = cast<ObjCInterfaceType>(T);
+    if (ObjCI->getDecl()->isInvalidDecl()) {
+      Width = 8;
+      Align = 8;
+      break;
+    }
     const ASTRecordLayout &Layout = getASTObjCInterfaceLayout(ObjCI->getDecl());
     Width = toBits(Layout.getSize());
     Align = toBits(Layout.getAlignment());
     break;
   }
   case Type::Record:
   case Type::Enum: {
     const auto *TT = cast<TagType>(T);

clang/lib/AST/RecordLayoutBuilder.cpp

 /// implementation. This may differ by including synthesized ivars.
 const ASTRecordLayout &
 ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
                           const ObjCImplementationDecl *Impl) const {
   // Retrieve the definition
   if (D->hasExternalLexicalStorage() && !D->getDefinition())
     getExternalSource()->CompleteType(const_cast<ObjCInterfaceDecl*>(D));
   D = D->getDefinition();
-  assert(D && D->isThisDeclarationADefinition() && "Invalid interface decl!");
+  assert(D && !D->isInvalidDecl() && D->isThisDeclarationADefinition() &&
+         "Invalid interface decl!");
 
   // Look up this layout, if already laid out, return what we have.
   const ObjCContainerDecl *Key =
     Impl ? (const ObjCContainerDecl*) Impl : (const ObjCContainerDecl*) D;
   if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
     return *Entry;
 
   // Add in synthesized ivar count if laying out an implementation.

clang/lib/Sema/SemaDecl.cpp

void Sema::ActOnTagDefinitionError(Scope *S, Decl *TagD) {
   PopDeclContext();
 }
 
 // Note that FieldName may be null for anonymous bitfields.
 ExprResult Sema::VerifyBitField(SourceLocation FieldLoc,
                                 IdentifierInfo *FieldName,
                                 QualType FieldTy, bool IsMsStruct,
                                 Expr *BitWidth, bool *ZeroWidth) {
+  assert(BitWidth);
+  if (BitWidth->containsErrors())
+    return ExprError();
+
   // Default to true; that shouldn't confuse checks for emptiness
   if (ZeroWidth)
     *ZeroWidth = true;
 
   // C99 6.7.2.1p4 - verify the field type.
   // C++ 9.6p3: A bit-field shall have integral or enumeration type.
   if (!FieldTy->isDependentType() && !FieldTy->isIntegralOrEnumerationType()) {
     // Handle incomplete and sizeless types with a specific error.

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

+// RUN: %clang_cc1 -fobjc-runtime=gcc -frecovery-ast -verify %s
+// RUN: %clang_cc1 -fobjc-runtime=gcc -fno-recovery-ast -verify %s
+
+@interface Ivar
+{
+  int Foo : foo(); // expected-error {{use of undeclared identifier}}
+};
+@end
+
+struct X { int Y: foo(); }; // expected-error {{use of undeclared identifier}}
+
+constexpr int s = sizeof(Ivar);
+constexpr int ss = sizeof(X);