Add 'nopartial' qualifier for availability attributes.

An optional nopartial can be placed after the platform name.
int bar() __attribute__((availability(macosx,nopartial,introduced=10.12))

When deploying back to a platform version prior to when the declaration was
introduced, with 'nopartial', Clang emits an error specifying that the function
is not introduced yet; without 'nopartial', the behavior stays the same: the
declaration is `weakly linked`.

A member is added to the end of AttributeList to save the location of the
'nopartial' keyword. A bool member is added to AvailabilityAttr.

The diagnostics for 'nopartial' not-yet-introduced is handled in the same way as
we handle unavailable cases.

Reviewed by Doug Gregor and Jordan Rose.

rdar://23791325

llvm-svn: 261163

1 files changed, 11 insertions, 2 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 5976c2c9f34..cbac36b7bff 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -137,7 +137,7 @@ DiagnoseAvailabilityOfDecl(Sema &S, NamedDecl *D, SourceLocation Loc,
 
   const ObjCPropertyDecl *ObjCPDecl = nullptr;
   if (Result == AR_Deprecated || Result == AR_Unavailable ||
-      AR_NotYetIntroduced) {
+      Result == AR_NotYetIntroduced) {
     if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
       if (const ObjCPropertyDecl *PD = MD->findPropertyDecl()) {
         AvailabilityResult PDeclResult = PD->getAvailability(nullptr);
@@ -159,11 +159,20 @@ DiagnoseAvailabilityOfDecl(Sema &S, NamedDecl *D, SourceLocation Loc,
       break;
 
     case AR_NotYetIntroduced: {
+      // With nopartial, the compiler will emit delayed error just like how
+      // "deprecated, unavailable" are handled.
+      AvailabilityAttr *AA = D->getAttr<AvailabilityAttr>();
+      if (AA && AA->getNopartial() &&
+          S.getCurContextAvailability() != AR_NotYetIntroduced)
+        S.EmitAvailabilityWarning(Sema::AD_NotYetIntroduced,
+                                  D, Message, Loc, UnknownObjCClass, ObjCPDecl,
+                                  ObjCPropertyAccess);
+
       // Don't do this for enums, they can't be redeclared.
       if (isa<EnumConstantDecl>(D) || isa<EnumDecl>(D))
         break;
  
-      bool Warn = !D->getAttr<AvailabilityAttr>()->isInherited();
+      bool Warn = !AA->isInherited();
       // Objective-C method declarations in categories are not modelled as
       // redeclarations, so manually look for a redeclaration in a category
       // if necessary.