2 files changed, 55 insertions, 16 deletions

diff --git a/clang/lib/Sema/SemaCast.cpp b/clang/lib/Sema/SemaCast.cpp
index 21a4d107ba2..0958943f9ef 100644
--- a/clang/lib/Sema/SemaCast.cpp
+++ b/clang/lib/Sema/SemaCast.cpp
@@ -2323,19 +2323,41 @@ void CastOperation::checkAddressSpaceCast(QualType SrcType, QualType DestType) {
   // In OpenCL only conversions between pointers to objects in overlapping
   // addr spaces are allowed. v2.0 s6.5.5 - Generic addr space overlaps
   // with any named one, except for constant.
+
+  // Converting the top level pointee addrspace is permitted for compatible
+  // addrspaces (such as 'generic int *' to 'local int *' or vice versa), but
+  // if any of the nested pointee addrspaces differ, we emit a warning
+  // regardless of addrspace compatibility. This makes
+  //   local int ** p;
+  //   return (generic int **) p;
+  // warn even though local -> generic is permitted.
   if (Self.getLangOpts().OpenCL) {
-    auto SrcPtrType = SrcType->getAs<PointerType>();
-    if (!SrcPtrType)
-      return;
-    auto DestPtrType = DestType->getAs<PointerType>();
-    if (!DestPtrType)
-      return;
-    if (!DestPtrType->isAddressSpaceOverlapping(*SrcPtrType)) {
-      Self.Diag(OpRange.getBegin(),
-                diag::err_typecheck_incompatible_address_space)
-          << SrcType << DestType << Sema::AA_Casting
-          << SrcExpr.get()->getSourceRange();
-      SrcExpr = ExprError();
+    const Type *DestPtr, *SrcPtr;
+    bool Nested = false;
+    unsigned DiagID = diag::err_typecheck_incompatible_address_space;
+    DestPtr = Self.getASTContext().getCanonicalType(DestType.getTypePtr()),
+    SrcPtr  = Self.getASTContext().getCanonicalType(SrcType.getTypePtr());
+
+    while (isa<PointerType>(DestPtr) && isa<PointerType>(SrcPtr)) {
+      const PointerType *DestPPtr = cast<PointerType>(DestPtr);
+      const PointerType *SrcPPtr = cast<PointerType>(SrcPtr);
+      QualType DestPPointee = DestPPtr->getPointeeType();
+      QualType SrcPPointee = SrcPPtr->getPointeeType();
+      if (Nested ? DestPPointee.getAddressSpace() !=
+                   SrcPPointee.getAddressSpace()
+                 : !DestPPtr->isAddressSpaceOverlapping(*SrcPPtr)) {
+        Self.Diag(OpRange.getBegin(), DiagID)
+            << SrcType << DestType << Sema::AA_Casting
+            << SrcExpr.get()->getSourceRange();
+        if (!Nested)
+          SrcExpr = ExprError();
+        return;
+      }
+
+      DestPtr = DestPPtr->getPointeeType().getTypePtr();
+      SrcPtr = SrcPPtr->getPointeeType().getTypePtr();
+      Nested = true;
+      DiagID = diag::ext_nested_pointer_qualifier_mismatch;
     }
   }
 }
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index d8c08961471..8bb306e66d6 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -7724,9 +7724,9 @@ checkPointerTypesForAssignment(Sema &S, QualType LHSType, QualType RHSType) {
   }
 
   if (!lhq.compatiblyIncludes(rhq)) {
-    // Treat address-space mismatches as fatal.  TODO: address subspaces
+    // Treat address-space mismatches as fatal.
     if (!lhq.isAddressSpaceSupersetOf(rhq))
-      ConvTy = Sema::IncompatiblePointerDiscardsQualifiers;
+      return Sema::IncompatiblePointerDiscardsQualifiers;
 
     // It's okay to add or remove GC or lifetime qualifiers when converting to
     // and from void*.
@@ -7799,8 +7799,22 @@ checkPointerTypesForAssignment(Sema &S, QualType LHSType, QualType RHSType) {
     // level of indirection, this must be the issue.
     if (isa<PointerType>(lhptee) && isa<PointerType>(rhptee)) {
       do {
-        lhptee = cast<PointerType>(lhptee)->getPointeeType().getTypePtr();
-        rhptee = cast<PointerType>(rhptee)->getPointeeType().getTypePtr();
+        std::tie(lhptee, lhq) =
+          cast<PointerType>(lhptee)->getPointeeType().split().asPair();
+        std::tie(rhptee, rhq) =
+          cast<PointerType>(rhptee)->getPointeeType().split().asPair();
+
+        // Inconsistent address spaces at this point is invalid, even if the
+        // address spaces would be compatible.
+        // FIXME: This doesn't catch address space mismatches for pointers of
+        // different nesting levels, like:
+        //   __local int *** a;
+        //   int ** b = a;
+        // It's not clear how to actually determine when such pointers are
+        // invalidly incompatible.
+        if (lhq.getAddressSpace() != rhq.getAddressSpace())
+          return Sema::IncompatibleNestedPointerAddressSpaceMismatch;
+
       } while (isa<PointerType>(lhptee) && isa<PointerType>(rhptee));
 
       if (lhptee == rhptee)
@@ -14213,6 +14227,9 @@ bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
   case IncompatibleNestedPointerQualifiers:
     DiagKind = diag::ext_nested_pointer_qualifier_mismatch;
     break;
+  case IncompatibleNestedPointerAddressSpaceMismatch:
+    DiagKind = diag::err_typecheck_incompatible_nested_address_space;
+    break;
   case IntToBlockPointer:
     DiagKind = diag::err_int_to_block_pointer;
     break;