Don't inherit availability information when implementing a protocol requirement.

When an Objective-C method implements a protocol requirement, do not
inherit any availability information from the protocol
requirement. Rather, check that the implementation is not less
available than the protocol requirement, as we do when overriding a
method that has availability. Fixes rdar://problem/22734745.

llvm-svn: 248949

1 files changed, 17 insertions, 10 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 571c9baa048..a359ef49311 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -2175,14 +2175,15 @@ static bool mergeAlignedAttrs(Sema &S, NamedDecl *New, Decl *Old) {
 }
 
 static bool mergeDeclAttribute(Sema &S, NamedDecl *D,
-                               const InheritableAttr *Attr, bool Override) {
+                               const InheritableAttr *Attr,
+                               Sema::AvailabilityMergeKind AMK) {
   InheritableAttr *NewAttr = nullptr;
   unsigned AttrSpellingListIndex = Attr->getSpellingListIndex();
   if (const auto *AA = dyn_cast<AvailabilityAttr>(Attr))
     NewAttr = S.mergeAvailabilityAttr(D, AA->getRange(), AA->getPlatform(),
                                       AA->getIntroduced(), AA->getDeprecated(),
                                       AA->getObsoleted(), AA->getUnavailable(),
-                                      AA->getMessage(), Override,
+                                      AA->getMessage(), AMK,
                                       AttrSpellingListIndex);
   else if (const auto *VA = dyn_cast<VisibilityAttr>(Attr))
     NewAttr = S.mergeVisibilityAttr(D, VA->getRange(), VA->getVisibility(),
@@ -2219,7 +2220,11 @@ static bool mergeDeclAttribute(Sema &S, NamedDecl *D,
     // AlignedAttrs are handled separately, because we need to handle all
     // such attributes on a declaration at the same time.
     NewAttr = nullptr;
-  else if (isa<DeprecatedAttr>(Attr) && Override)
+  else if (isa<DeprecatedAttr>(Attr)  &&
+           (AMK == Sema::AMK_Override ||
+            AMK == Sema::AMK_ProtocolImplementation))
+    NewAttr = nullptr;
+  else if (isa<UnavailableAttr>(Attr) && AMK == Sema::AMK_ProtocolImplementation)
     NewAttr = nullptr;
   else if (Attr->duplicatesAllowed() || !DeclHasAttr(D, Attr))
     NewAttr = cast<InheritableAttr>(Attr->clone(S.Context));
@@ -2366,8 +2371,8 @@ void Sema::mergeDeclAttributes(NamedDecl *New, Decl *Old,
   if (!foundAny) New->setAttrs(AttrVec());
 
   for (auto *I : Old->specific_attrs<InheritableAttr>()) {
-    bool Override = false;
     // Ignore deprecated/unavailable/availability attributes if requested.
+    AvailabilityMergeKind LocalAMK = AMK_None;
     if (isa<DeprecatedAttr>(I) ||
         isa<UnavailableAttr>(I) ||
         isa<AvailabilityAttr>(I)) {
@@ -2376,10 +2381,9 @@ void Sema::mergeDeclAttributes(NamedDecl *New, Decl *Old,
         continue;
 
       case AMK_Redeclaration:
-        break;
-
       case AMK_Override:
-        Override = true;
+      case AMK_ProtocolImplementation:
+        LocalAMK = AMK;
         break;
       }
     }
@@ -2388,7 +2392,7 @@ void Sema::mergeDeclAttributes(NamedDecl *New, Decl *Old,
     if (isa<UsedAttr>(I))
       continue;
 
-    if (mergeDeclAttribute(*this, New, I, Override))
+    if (mergeDeclAttribute(*this, New, I, LocalAMK))
       foundAny = true;
   }
 
@@ -3156,8 +3160,11 @@ void Sema::mergeObjCMethodDecls(ObjCMethodDecl *newMethod,
 
   // Merge the attributes, including deprecated/unavailable
   AvailabilityMergeKind MergeKind =
-    isa<ObjCImplDecl>(newMethod->getDeclContext()) ? AMK_Redeclaration
-                                                   : AMK_Override;
+    isa<ObjCProtocolDecl>(oldMethod->getDeclContext())
+      ? AMK_ProtocolImplementation
+      : isa<ObjCImplDecl>(newMethod->getDeclContext()) ? AMK_Redeclaration
+                                                       : AMK_Override;
+
   mergeDeclAttributes(newMethod, oldMethod, MergeKind);
 
   // Merge attributes from the parameters.