ObjectiveC Generics: Start using ObjCTypeParamType.

For ObjC type parameter, we used to have TypedefType that is canonicalized to
id or the bound type. We can't represent "T <protocol>" and thus will lose
the type information in the following example:
@interface MyMutableDictionary<KeyType, ObjectType> : NSObject
- (void)setObject:(ObjectType)obj forKeyedSubscript:(KeyType <NSCopying>)key;
@end
MyMutableDictionary<NSString *, NSString *> *stringsByString;
NSNumber *n1, *n2;
stringsByString[n1] = n2;
--> no warning on type mismatch of the key.

To fix the problem, we introduce a new type ObjCTypeParamType that supports
a list of protocol qualifiers.

We create ObjCTypeParamType for ObjCTypeParamDecl when we create
ObjCTypeParamDecl. We also substitute ObjCTypeParamType instead of TypedefType
on an ObjCTypeParamDecl.

rdar://24619481
rdar://25060179

Differential Revision: http://reviews.llvm.org/D23080


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@281358 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 15 insertions, 4 deletions

diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index 556d225612..4aa07568dc 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -1081,13 +1081,24 @@ QualType QualType::substObjCTypeArgs(
 
     // Replace an Objective-C type parameter reference with the corresponding
     // type argument.
-    if (const auto *typedefTy = dyn_cast<TypedefType>(splitType.Ty)) {
-      if (auto *typeParam = dyn_cast<ObjCTypeParamDecl>(typedefTy->getDecl())) {
+    if (const auto *OTPTy = dyn_cast<ObjCTypeParamType>(splitType.Ty)) {
+      if (auto *typeParam = dyn_cast<ObjCTypeParamDecl>(OTPTy->getDecl())) {
         // If we have type arguments, use them.
         if (!typeArgs.empty()) {
-          // FIXME: Introduce SubstObjCTypeParamType ?
           QualType argType = typeArgs[typeParam->getIndex()];
-          return ctx.getQualifiedType(argType, splitType.Quals);
+          if (OTPTy->qual_empty())
+            return ctx.getQualifiedType(argType, splitType.Quals);
+
+          // Apply protocol lists if exists.
+          bool hasError;
+          SmallVector<ObjCProtocolDecl*, 8> protocolsVec;
+          protocolsVec.append(OTPTy->qual_begin(),
+                              OTPTy->qual_end());
+          ArrayRef<ObjCProtocolDecl *> protocolsToApply = protocolsVec;
+          QualType resultTy = ctx.applyObjCProtocolQualifiers(argType,
+              protocolsToApply, hasError, true/*allowOnPointerType*/);
+
+          return ctx.getQualifiedType(resultTy, splitType.Quals);
         }
 
         switch (context) {