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

6 files changed, 149 insertions, 46 deletions

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index cac97ce05fa..fa1a6ff8fc5 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2410,15 +2410,19 @@ def warn_availability_version_ordering : Warning<
 def warn_mismatched_availability: Warning<
   "availability does not match previous declaration">, InGroup<Availability>;
 def warn_mismatched_availability_override : Warning<
-  "overriding method %select{introduced after|"
-  "deprecated before|obsoleted before}0 overridden method on %1 (%2 vs. %3)">, 
-  InGroup<Availability>;
+  "%select{|overriding }4method %select{introduced after|"
+  "deprecated before|obsoleted before}0 "
+  "%select{the protocol method it implements|overridden method}4 "
+  "on %1 (%2 vs. %3)">, InGroup<Availability>;
 def warn_mismatched_availability_override_unavail : Warning<
-  "overriding method cannot be unavailable on %0 when its overridden method is "
+  "%select{|overriding }1method cannot be unavailable on %0 when "
+  "%select{the protocol method it implements|its overridden method}1 is "
   "available">,
   InGroup<Availability>;
 def note_overridden_method : Note<
   "overridden method is here">;
+def note_protocol_method : Note<
+  "protocol method is here">;
 
 // Thread Safety Attributes
 def warn_invalid_capability_name : Warning<
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 09b46ce77b6..1cf57ca36de 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -2062,6 +2062,22 @@ public:
                                 TypeSourceInfo *TInfo);
   bool isIncompatibleTypedef(TypeDecl *Old, TypedefNameDecl *New);
 
+  /// \brief Describes the kind of merge to perform for availability
+  /// attributes (including "deprecated", "unavailable", and "availability").
+  enum AvailabilityMergeKind {
+    /// \brief Don't merge availability attributes at all.
+    AMK_None,
+    /// \brief Merge availability attributes for a redeclaration, which requires
+    /// an exact match.
+    AMK_Redeclaration,
+    /// \brief Merge availability attributes for an override, which requires
+    /// an exact match or a weakening of constraints.
+    AMK_Override,
+    /// \brief Merge availability attributes for an implementation of
+    /// a protocol requirement.
+    AMK_ProtocolImplementation,
+  };
+
   /// Attribute merging methods. Return true if a new attribute was added.
   AvailabilityAttr *mergeAvailabilityAttr(NamedDecl *D, SourceRange Range,
                                           IdentifierInfo *Platform,
@@ -2070,7 +2086,7 @@ public:
                                           VersionTuple Obsoleted,
                                           bool IsUnavailable,
                                           StringRef Message,
-                                          bool Override,
+                                          AvailabilityMergeKind AMK,
                                           unsigned AttrSpellingListIndex);
   TypeVisibilityAttr *mergeTypeVisibilityAttr(Decl *D, SourceRange Range,
                                        TypeVisibilityAttr::VisibilityType Vis,
@@ -2099,19 +2115,6 @@ public:
   OptimizeNoneAttr *mergeOptimizeNoneAttr(Decl *D, SourceRange Range,
                                           unsigned AttrSpellingListIndex);
 
-  /// \brief Describes the kind of merge to perform for availability
-  /// attributes (including "deprecated", "unavailable", and "availability").
-  enum AvailabilityMergeKind {
-    /// \brief Don't merge availability attributes at all.
-    AMK_None,
-    /// \brief Merge availability attributes for a redeclaration, which requires
-    /// an exact match.
-    AMK_Redeclaration,
-    /// \brief Merge availability attributes for an override, which requires
-    /// an exact match or a weakening of constraints.
-    AMK_Override
-  };
-
   void mergeDeclAttributes(NamedDecl *New, Decl *Old,
                            AvailabilityMergeKind AMK = AMK_Redeclaration);
   void MergeTypedefNameDecl(TypedefNameDecl *New, LookupResult &OldDecls);
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.
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 8218c20696d..3cf9567889f 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -1821,12 +1821,24 @@ AvailabilityAttr *Sema::mergeAvailabilityAttr(NamedDecl *D, SourceRange Range,
                                               VersionTuple Obsoleted,
                                               bool IsUnavailable,
                                               StringRef Message,
-                                              bool Override,
+                                              AvailabilityMergeKind AMK,
                                               unsigned AttrSpellingListIndex) {
   VersionTuple MergedIntroduced = Introduced;
   VersionTuple MergedDeprecated = Deprecated;
   VersionTuple MergedObsoleted = Obsoleted;
   bool FoundAny = false;
+  bool OverrideOrImpl = false;
+  switch (AMK) {
+  case AMK_None:
+  case AMK_Redeclaration:
+    OverrideOrImpl = false;
+    break;
+
+  case AMK_Override:
+  case AMK_ProtocolImplementation:
+    OverrideOrImpl = true;
+    break;
+  }
 
   if (D->hasAttrs()) {
     AttrVec &Attrs = D->getAttrs();
@@ -1849,24 +1861,24 @@ AvailabilityAttr *Sema::mergeAvailabilityAttr(NamedDecl *D, SourceRange Range,
       VersionTuple OldObsoleted = OldAA->getObsoleted();
       bool OldIsUnavailable = OldAA->getUnavailable();
 
-      if (!versionsMatch(OldIntroduced, Introduced, Override) ||
-          !versionsMatch(Deprecated, OldDeprecated, Override) ||
-          !versionsMatch(Obsoleted, OldObsoleted, Override) ||
+      if (!versionsMatch(OldIntroduced, Introduced, OverrideOrImpl) ||
+          !versionsMatch(Deprecated, OldDeprecated, OverrideOrImpl) ||
+          !versionsMatch(Obsoleted, OldObsoleted, OverrideOrImpl) ||
           !(OldIsUnavailable == IsUnavailable ||
-            (Override && !OldIsUnavailable && IsUnavailable))) {
-        if (Override) {
+            (OverrideOrImpl && !OldIsUnavailable && IsUnavailable))) {
+        if (OverrideOrImpl) {
           int Which = -1;
           VersionTuple FirstVersion;
           VersionTuple SecondVersion;
-          if (!versionsMatch(OldIntroduced, Introduced, Override)) {
+          if (!versionsMatch(OldIntroduced, Introduced, OverrideOrImpl)) {
             Which = 0;
             FirstVersion = OldIntroduced;
             SecondVersion = Introduced;
-          } else if (!versionsMatch(Deprecated, OldDeprecated, Override)) {
+          } else if (!versionsMatch(Deprecated, OldDeprecated, OverrideOrImpl)) {
             Which = 1;
             FirstVersion = Deprecated;
             SecondVersion = OldDeprecated;
-          } else if (!versionsMatch(Obsoleted, OldObsoleted, Override)) {
+          } else if (!versionsMatch(Obsoleted, OldObsoleted, OverrideOrImpl)) {
             Which = 2;
             FirstVersion = Obsoleted;
             SecondVersion = OldObsoleted;
@@ -1875,15 +1887,20 @@ AvailabilityAttr *Sema::mergeAvailabilityAttr(NamedDecl *D, SourceRange Range,
           if (Which == -1) {
             Diag(OldAA->getLocation(),
                  diag::warn_mismatched_availability_override_unavail)
-              << AvailabilityAttr::getPrettyPlatformName(Platform->getName());
+              << AvailabilityAttr::getPrettyPlatformName(Platform->getName())
+              << (AMK == AMK_Override);
           } else {
             Diag(OldAA->getLocation(),
                  diag::warn_mismatched_availability_override)
               << Which
               << AvailabilityAttr::getPrettyPlatformName(Platform->getName())
-              << FirstVersion.getAsString() << SecondVersion.getAsString();
+              << FirstVersion.getAsString() << SecondVersion.getAsString()
+              << (AMK == AMK_Override);
           }
-          Diag(Range.getBegin(), diag::note_overridden_method);
+          if (AMK == AMK_Override)
+            Diag(Range.getBegin(), diag::note_overridden_method);
+          else
+            Diag(Range.getBegin(), diag::note_protocol_method);
         } else {
           Diag(OldAA->getLocation(), diag::warn_mismatched_availability);
           Diag(Range.getBegin(), diag::note_previous_attribute);
@@ -1926,11 +1943,11 @@ AvailabilityAttr *Sema::mergeAvailabilityAttr(NamedDecl *D, SourceRange Range,
       MergedObsoleted == Obsoleted)
     return nullptr;
 
-  // Only create a new attribute if !Override, but we want to do
+  // Only create a new attribute if !OverrideOrImpl, but we want to do
   // the checking.
   if (!checkAvailabilityAttr(*this, Range, Platform, MergedIntroduced,
                              MergedDeprecated, MergedObsoleted) &&
-      !Override) {
+      !OverrideOrImpl) {
     return ::new (Context) AvailabilityAttr(Range, Context, Platform,
                                             Introduced, Deprecated,
                                             Obsoleted, IsUnavailable, Message,
@@ -1971,7 +1988,7 @@ static void handleAvailabilityAttr(Sema &S, Decl *D,
                                                       Deprecated.Version,
                                                       Obsoleted.Version,
                                                       IsUnavailable, Str,
-                                                      /*Override=*/false,
+                                                      Sema::AMK_None,
                                                       Index);
   if (NewAttr)
     D->addAttr(NewAttr);
diff --git a/clang/test/ARCMT/checking.m b/clang/test/ARCMT/checking.m
index 6a7cf76c386..11a57538d73 100644
--- a/clang/test/ARCMT/checking.m
+++ b/clang/test/ARCMT/checking.m
@@ -44,9 +44,9 @@ struct UnsafeS {
 };
 
 @interface A : NSObject
-- (id)retain; // expected-note {{'retain' has been explicitly marked unavailable here}}
-- (id)retainCount; // expected-note {{'retainCount' has been explicitly marked unavailable here}}
-- (id)autorelease; // expected-note 2 {{'autorelease' has been explicitly marked unavailable here}}
+- (id)retain __attribute__((unavailable)); // expected-note {{'retain' has been explicitly marked unavailable here}}
+- (id)retainCount __attribute__((unavailable)); // expected-note {{'retainCount' has been explicitly marked unavailable here}}
+- (id)autorelease __attribute__((unavailable)); // expected-note 2 {{'autorelease' has been explicitly marked unavailable here}}
 - (id)init;
 - (oneway void)release;
 - (void)dealloc;
diff --git a/clang/test/SemaObjC/attr-availability.m b/clang/test/SemaObjC/attr-availability.m
index ea97e0e472d..8323139e590 100644
--- a/clang/test/SemaObjC/attr-availability.m
+++ b/clang/test/SemaObjC/attr-availability.m
@@ -23,6 +23,7 @@
 - (void)overridden4 __attribute__((availability(macosx,deprecated=10.3))); // expected-note{{overridden method is here}}
 - (void)overridden5 __attribute__((availability(macosx,unavailable)));
 - (void)overridden6 __attribute__((availability(macosx,introduced=10.3))); // expected-note{{overridden method is here}}
+- (void)unavailableMethod __attribute__((unavailable));
 @end
 
 // rdar://11475360
@@ -35,6 +36,7 @@
 - (void)overridden4 __attribute__((availability(macosx,deprecated=10.2))); // expected-warning{{overriding method deprecated before overridden method on OS X (10.3 vs. 10.2)}}
 - (void)overridden5 __attribute__((availability(macosx,introduced=10.3)));
 - (void)overridden6 __attribute__((availability(macosx,unavailable))); // expected-warning{{overriding method cannot be unavailable on OS X when its overridden method is available}}
+- (void)unavailableMethod; // does *not* inherit unavailability
 @end
 
 void f(A *a, B *b) {
@@ -206,3 +208,73 @@ void use_myEnum() {
   // expected-error@+1 {{MyEnum_Blah' is unavailable: not available}}
   MyEnum e = MyEnum_Blah; 
 }
+
+// Test that the availability of (optional) protocol methods is not
+// inherited be implementations of those protocol methods.
+@protocol AvailabilityP2
+@optional
+-(void)methodA __attribute__((availability(macosx,introduced=10.1,deprecated=10.2))); // expected-note 4{{'methodA' has been explicitly marked deprecated here}} \
+// expected-note 2{{protocol method is here}}
+-(void)methodB __attribute__((unavailable)); // expected-note 4{{'methodB' has been explicitly marked unavailable here}}
+-(void)methodC;
+@end
+
+void testAvailabilityP2(id<AvailabilityP2> obj) {
+  [obj methodA]; // expected-warning{{'methodA' is deprecated: first deprecated in OS X 10.2}}
+  [obj methodB]; // expected-error{{'methodB' is unavailable}}
+}
+
+@interface ImplementsAvailabilityP2a <AvailabilityP2>
+-(void)methodA;
+-(void)methodB;
+@end
+
+void testImplementsAvailabilityP2a(ImplementsAvailabilityP2a *obj) {
+  [obj methodA]; // okay: availability not inherited
+  [obj methodB]; // okay: unavailability not inherited
+}
+
+__attribute__((objc_root_class))
+@interface ImplementsAvailabilityP2b <AvailabilityP2>
+@end
+
+@implementation ImplementsAvailabilityP2b
+-(void)methodA {
+  // Make sure we're not inheriting availability.
+  id<AvailabilityP2> obj = self;
+  [obj methodA]; // expected-warning{{'methodA' is deprecated: first deprecated in OS X 10.2}}
+  [obj methodB]; // expected-error{{'methodB' is unavailable}}
+}
+-(void)methodB {
+  // Make sure we're not inheriting unavailability.
+  id<AvailabilityP2> obj = self;
+  [obj methodA]; // expected-warning{{'methodA' is deprecated: first deprecated in OS X 10.2}}
+  [obj methodB]; // expected-error{{'methodB' is unavailable}}
+}
+
+@end
+
+void testImplementsAvailabilityP2b(ImplementsAvailabilityP2b *obj) {
+  // still get warnings/errors because we see the protocol version.
+
+  [obj methodA]; // expected-warning{{'methodA' is deprecated: first deprecated in OS X 10.2}}
+  [obj methodB]; // expected-error{{'methodB' is unavailable}}
+}
+
+__attribute__((objc_root_class))
+@interface ImplementsAvailabilityP2c <AvailabilityP2>
+-(void)methodA __attribute__((availability(macosx,introduced=10.2))); // expected-warning{{method introduced after the protocol method it implements on OS X (10.2 vs. 10.1)}}
+-(void)methodB __attribute__((unavailable));
+@end
+
+__attribute__((objc_root_class))
+@interface ImplementsAvailabilityP2d <AvailabilityP2>
+@end
+
+@implementation ImplementsAvailabilityP2d
+-(void)methodA __attribute__((availability(macosx,introduced=10.2))) // expected-warning{{method introduced after the protocol method it implements on OS X (10.2 vs. 10.1)}}
+{
+}
+-(void)methodB __attribute__((unavailable)) {
+}
+@end