Fix predefine for __NSConstantString struct type

Per review feedback the name was wrong and it can be used outside
Objective-C.

Unfortunately, making the internal struct visible broke some ASTMatchers
tests that assumed that the first record decl would be from user code,
rather than a builtin type.  I'm worried that this will also affect
users' code.  So this patch adds a typedef to wrap the internal struct
and only makes the typedef visible to namelookup.  This is sufficient to
allow the ASTReader to merge the decls we need without making the struct
itself visible.

rdar://problem/24425801

llvm-svn: 259734

1 files changed, 34 insertions, 18 deletions

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index fc5ff8668e9..06fb46e2f7f 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -738,12 +738,13 @@ ASTContext::ASTContext(LangOptions &LOpts, SourceManager &SM,
       BuiltinVaListDecl(nullptr), BuiltinMSVaListDecl(nullptr),
       ObjCIdDecl(nullptr), ObjCSelDecl(nullptr), ObjCClassDecl(nullptr),
       ObjCProtocolClassDecl(nullptr), BOOLDecl(nullptr),
-      CFConstantStringTypeDecl(nullptr), ObjCInstanceTypeDecl(nullptr),
-      FILEDecl(nullptr), jmp_bufDecl(nullptr), sigjmp_bufDecl(nullptr),
-      ucontext_tDecl(nullptr), BlockDescriptorType(nullptr),
-      BlockDescriptorExtendedType(nullptr), cudaConfigureCallDecl(nullptr),
-      FirstLocalImport(), LastLocalImport(), ExternCContext(nullptr),
-      MakeIntegerSeqDecl(nullptr), SourceMgr(SM), LangOpts(LOpts),
+      CFConstantStringTagDecl(nullptr), CFConstantStringTypeDecl(nullptr),
+      ObjCInstanceTypeDecl(nullptr), FILEDecl(nullptr), jmp_bufDecl(nullptr),
+      sigjmp_bufDecl(nullptr), ucontext_tDecl(nullptr),
+      BlockDescriptorType(nullptr), BlockDescriptorExtendedType(nullptr),
+      cudaConfigureCallDecl(nullptr), FirstLocalImport(), LastLocalImport(),
+      ExternCContext(nullptr), MakeIntegerSeqDecl(nullptr), SourceMgr(SM),
+      LangOpts(LOpts),
       SanitizerBL(new SanitizerBlacklist(LangOpts.SanitizerBlacklistFiles, SM)),
       AddrSpaceMap(nullptr), Target(nullptr), AuxTarget(nullptr),
       PrintingPolicy(LOpts), Idents(idents), Selectors(sels),
@@ -4868,12 +4869,12 @@ int ASTContext::getIntegerTypeOrder(QualType LHS, QualType RHS) const {
   return 1;
 }
 
-TagDecl *ASTContext::getCFConstantStringDecl() const {
+TypedefDecl *ASTContext::getCFConstantStringDecl() const {
   if (!CFConstantStringTypeDecl) {
-    // This type is designed to be compatible with NSConstantString, but cannot
-    // use the same name, since NSConstantString is an interface.
-    CFConstantStringTypeDecl = buildImplicitRecord("__NSConstantString");
-    CFConstantStringTypeDecl->startDefinition();
+    assert(!CFConstantStringTagDecl &&
+           "tag and typedef should be initialized together");
+    CFConstantStringTagDecl = buildImplicitRecord("__NSConstantString_tag");
+    CFConstantStringTagDecl->startDefinition();
 
     QualType FieldTypes[4];
 
@@ -4888,7 +4889,7 @@ TagDecl *ASTContext::getCFConstantStringDecl() const {
 
     // Create fields
     for (unsigned i = 0; i < 4; ++i) {
-      FieldDecl *Field = FieldDecl::Create(*this, CFConstantStringTypeDecl,
+      FieldDecl *Field = FieldDecl::Create(*this, CFConstantStringTagDecl,
                                            SourceLocation(),
                                            SourceLocation(), nullptr,
                                            FieldTypes[i], /*TInfo=*/nullptr,
@@ -4896,18 +4897,29 @@ TagDecl *ASTContext::getCFConstantStringDecl() const {
                                            /*Mutable=*/false,
                                            ICIS_NoInit);
       Field->setAccess(AS_public);
-      CFConstantStringTypeDecl->addDecl(Field);
+      CFConstantStringTagDecl->addDecl(Field);
     }
 
-    CFConstantStringTypeDecl->completeDefinition();
+    CFConstantStringTagDecl->completeDefinition();
+    // This type is designed to be compatible with NSConstantString, but cannot
+    // use the same name, since NSConstantString is an interface.
+    auto tagType = getTagDeclType(CFConstantStringTagDecl);
+    CFConstantStringTypeDecl =
+        buildImplicitTypedef(tagType, "__NSConstantString");
   }
 
   return CFConstantStringTypeDecl;
 }
 
+RecordDecl *ASTContext::getCFConstantStringTagDecl() const {
+  if (!CFConstantStringTagDecl)
+    getCFConstantStringDecl(); // Build the tag and the typedef.
+  return CFConstantStringTagDecl;
+}
+
 // getCFConstantStringType - Return the type used for constant CFStrings.
 QualType ASTContext::getCFConstantStringType() const {
-  return getTagDeclType(getCFConstantStringDecl());
+  return getTypedefType(getCFConstantStringDecl());
 }
 
 QualType ASTContext::getObjCSuperType() const {
@@ -4920,9 +4932,13 @@ QualType ASTContext::getObjCSuperType() const {
 }
 
 void ASTContext::setCFConstantStringType(QualType T) {
-  const RecordType *Rec = T->getAs<RecordType>();
-  assert(Rec && "Invalid CFConstantStringType");
-  CFConstantStringTypeDecl = Rec->getDecl();
+  const TypedefType *TD = T->getAs<TypedefType>();
+  assert(TD && "Invalid CFConstantStringType");
+  CFConstantStringTypeDecl = cast<TypedefDecl>(TD->getDecl());
+  auto TagType =
+      CFConstantStringTypeDecl->getUnderlyingType()->getAs<RecordType>();
+  assert(TagType && "Invalid CFConstantStringType");
+  CFConstantStringTagDecl = TagType->getDecl();
 }
 
 QualType ASTContext::getBlockDescriptorType() const {