Substitute type arguments into uses of Objective-C interface members.

When messaging a method that was defined in an Objective-C class (or
category or extension thereof) that has type parameters, substitute
the type arguments for those type parameters. Similarly, substitute
into property accesses, instance variables, and other references.

This includes general infrastructure for substituting the type
arguments associated with an ObjCObject(Pointer)Type into a type
referenced within a particular context, handling all of the
substitutions required to deal with (e.g.) inheritance involving
parameterized classes. In cases where no type arguments are available
(e.g., because we're messaging via some unspecialized type, id, etc.),
we substitute in the type bounds for the type parameters instead.

Example:

  @interface NSSet<T : id<NSCopying>> : NSObject <NSCopying>
  - (T)firstObject;
  @end

  void f(NSSet<NSString *> *stringSet, NSSet *anySet) {
    [stringSet firstObject]; // produces NSString*
    [anySet firstObject]; // produces id<NSCopying> (the bound)
  }

When substituting for the type parameters given an unspecialized
context (i.e., no specific type arguments were given), substituting
the type bounds unconditionally produces type signatures that are too
strong compared to the pre-generics signatures. Instead, use the
following rule:

  - In covariant positions, such as method return types, replace type
    parameters with “id” or “Class” (the latter only when the type
    parameter bound is “Class” or qualified class, e.g,
    “Class<NSCopying>”)
  - In other positions (e.g., parameter types), replace type
    parameters with their type bounds.
  - When a specialized Objective-C object or object pointer type
    contains a type parameter in its type arguments (e.g.,
    NSArray<T>*, but not NSArray<NSString *> *), replace the entire
    object/object pointer type with its unspecialized version (e.g.,
    NSArray *).

llvm-svn: 241543

1 files changed, 9 insertions, 12 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index c6b53d03890..afc9279cba1 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -2466,8 +2466,8 @@ Sema::LookupInObjCMethod(LookupResult &Lookup, Scope *S,
         Diag(Loc, diag::warn_direct_ivar_access) << IV->getDeclName();
 
       ObjCIvarRefExpr *Result = new (Context)
-          ObjCIvarRefExpr(IV, IV->getType(), Loc, IV->getLocation(),
-                          SelfExpr.get(), true, true);
+          ObjCIvarRefExpr(IV, IV->getUsageType(SelfExpr.get()->getType()), Loc,
+                          IV->getLocation(), SelfExpr.get(), true, true);
 
       if (getLangOpts().ObjCAutoRefCount) {
         if (IV->getType().getObjCLifetime() == Qualifiers::OCL_Weak) {
@@ -5185,17 +5185,17 @@ Sema::ActOnInitList(SourceLocation LBraceLoc, MultiExprArg InitArgList,
 }
 
 /// Do an explicit extend of the given block pointer if we're in ARC.
-static void maybeExtendBlockObject(Sema &S, ExprResult &E) {
+void Sema::maybeExtendBlockObject(ExprResult &E) {
   assert(E.get()->getType()->isBlockPointerType());
   assert(E.get()->isRValue());
 
   // Only do this in an r-value context.
-  if (!S.getLangOpts().ObjCAutoRefCount) return;
+  if (!getLangOpts().ObjCAutoRefCount) return;
 
-  E = ImplicitCastExpr::Create(S.Context, E.get()->getType(),
+  E = ImplicitCastExpr::Create(Context, E.get()->getType(),
                                CK_ARCExtendBlockObject, E.get(),
                                /*base path*/ nullptr, VK_RValue);
-  S.ExprNeedsCleanups = true;
+  ExprNeedsCleanups = true;
 }
 
 /// Prepare a conversion of the given expression to an ObjC object
@@ -5205,7 +5205,7 @@ CastKind Sema::PrepareCastToObjCObjectPointer(ExprResult &E) {
   if (type->isObjCObjectPointerType()) {
     return CK_BitCast;
   } else if (type->isBlockPointerType()) {
-    maybeExtendBlockObject(*this, E);
+    maybeExtendBlockObject(E);
     return CK_BlockPointerToObjCPointerCast;
   } else {
     assert(type->isPointerType());
@@ -5247,7 +5247,7 @@ CastKind Sema::PrepareScalarCast(ExprResult &Src, QualType DestTy) {
         return CK_BitCast;
       if (SrcKind == Type::STK_CPointer)
         return CK_CPointerToObjCPointerCast;
-      maybeExtendBlockObject(*this, Src);
+      maybeExtendBlockObject(Src);
       return CK_BlockPointerToObjCPointerCast;
     case Type::STK_Bool:
       return CK_PointerToBoolean;
@@ -6980,7 +6980,7 @@ Sema::CheckAssignmentConstraints(QualType LHSType, ExprResult &RHS,
     // Only under strict condition T^ is compatible with an Objective-C pointer.
     if (RHSType->isBlockPointerType() && 
         LHSType->isBlockCompatibleObjCPointerType(Context)) {
-      maybeExtendBlockObject(*this, RHS);
+      maybeExtendBlockObject(RHS);
       Kind = CK_BlockPointerToObjCPointerCast;
       return Compatible;
     }
@@ -8189,9 +8189,6 @@ static bool hasIsEqualMethod(Sema &S, const Expr *LHS, const Expr *RHS) {
 
   // Get the LHS object's interface type.
   QualType InterfaceType = Type->getPointeeType();
-  if (const ObjCObjectType *iQFaceTy =
-      InterfaceType->getAsObjCQualifiedInterfaceType())
-    InterfaceType = iQFaceTy->getBaseType();
 
   // If the RHS isn't an Objective-C object, bail out.
   if (!RHS->getType()->isObjCObjectPointerType())