[Clang] Minimal support for availability attributes on partial specializations

clang/docs/ReleaseNotes.rst

@@ -586,6 +586,9 @@ Bug Fixes to Attribute Support
   ``__attribute__((unused))`` are still ignored after the definition, though
   this behavior may be relaxed in the future). (#GH135481)
 
+- Clang will warn if a completete type specializes a deprecated partial specialization.
+  (#GH44496)
+
 Bug Fixes to C++ Support
 ^^^^^^^^^^^^^^^^^^^^^^^^
 

clang/include/clang/Sema/Sema.h

@@ -2385,12 +2385,16 @@ class Sema final : public SemaBase {
   /// potential availability violations.
   sema::FunctionScopeInfo *getCurFunctionAvailabilityContext();
 
-  void DiagnoseAvailabilityOfDecl(NamedDecl *D, ArrayRef<SourceLocation> Locs,
-                                  const ObjCInterfaceDecl *UnknownObjCClass,
-                                  bool ObjCPropertyAccess,
-                                  bool AvoidPartialAvailabilityChecks = false,
-                                  ObjCInterfaceDecl *ClassReceiver = nullptr);
-
+  void DiagnoseAvailabilityOfDecl(
+      NamedDecl *D, ArrayRef<SourceLocation> Locs,
+      const ObjCInterfaceDecl *UnknownObjCClass = nullptr,
+      bool ObjCPropertyAccess = false,
+      bool AvoidPartialAvailabilityChecks = false,
+      ObjCInterfaceDecl *ClassReceiver = nullptr);
+
+  std::pair<AvailabilityResult, const NamedDecl *>
+  ShouldDiagnoseAvailabilityOfDecl(const NamedDecl *D, std::string *Message,
+                                   ObjCInterfaceDecl *ClassReceiver);
   ///@}
 
   //

clang/lib/Sema/SemaAvailability.cpp

@@ -90,10 +90,9 @@ static const AvailabilityAttr *getAttrForPlatform(ASTContext &Context,
 /// the availability attribute that is selected.
 /// \param ClassReceiver If we're checking the method of a class message
 /// send, the class. Otherwise nullptr.
-static std::pair<AvailabilityResult, const NamedDecl *>
-ShouldDiagnoseAvailabilityOfDecl(Sema &S, const NamedDecl *D,
-                                 std::string *Message,
-                                 ObjCInterfaceDecl *ClassReceiver) {
+std::pair<AvailabilityResult, const NamedDecl *>
+Sema::ShouldDiagnoseAvailabilityOfDecl(const NamedDecl *D, std::string *Message,
+                                       ObjCInterfaceDecl *ClassReceiver) {
   AvailabilityResult Result = D->getAvailability(Message);
 
   // For typedefs, if the typedef declaration appears available look
@@ -147,12 +146,12 @@ ShouldDiagnoseAvailabilityOfDecl(Sema &S, const NamedDecl *D,
 
   // For +new, infer availability from -init.
   if (const auto *MD = dyn_cast<ObjCMethodDecl>(D)) {
-    if (S.ObjC().NSAPIObj && ClassReceiver) {
+    if (ObjC().NSAPIObj && ClassReceiver) {
       ObjCMethodDecl *Init = ClassReceiver->lookupInstanceMethod(
-          S.ObjC().NSAPIObj->getInitSelector());
+          ObjC().NSAPIObj->getInitSelector());
       if (Init && Result == AR_Available && MD->isClassMethod() &&
-          MD->getSelector() == S.ObjC().NSAPIObj->getNewSelector() &&
-          MD->definedInNSObject(S.getASTContext())) {
+          MD->getSelector() == ObjC().NSAPIObj->getNewSelector() &&
+          MD->definedInNSObject(getASTContext())) {
         Result = Init->getAvailability(Message);
         D = Init;
       }
@@ -162,7 +161,6 @@ ShouldDiagnoseAvailabilityOfDecl(Sema &S, const NamedDecl *D,
   return {Result, D};
 }
 
-
 /// whether we should emit a diagnostic for \c K and \c DeclVersion in
 /// the context of \c Ctx. For example, we should emit an unavailable diagnostic
 /// in a deprecated context, but not the other way around.
@@ -876,7 +874,7 @@ void DiagnoseUnguardedAvailability::DiagnoseDeclAvailability(
   AvailabilityResult Result;
   const NamedDecl *OffendingDecl;
   std::tie(Result, OffendingDecl) =
-      ShouldDiagnoseAvailabilityOfDecl(SemaRef, D, nullptr, ReceiverClass);
+      SemaRef.ShouldDiagnoseAvailabilityOfDecl(D, nullptr, ReceiverClass);
   if (Result != AR_Available) {
     // All other diagnostic kinds have already been handled in
     // DiagnoseAvailabilityOfDecl.
@@ -1112,12 +1110,13 @@ void Sema::DiagnoseAvailabilityOfDecl(NamedDecl *D,
                                       bool ObjCPropertyAccess,
                                       bool AvoidPartialAvailabilityChecks,
                                       ObjCInterfaceDecl *ClassReceiver) {
+
   std::string Message;
   AvailabilityResult Result;
   const NamedDecl* OffendingDecl;
   // See if this declaration is unavailable, deprecated, or partial.
   std::tie(Result, OffendingDecl) =
-      ShouldDiagnoseAvailabilityOfDecl(*this, D, &Message, ClassReceiver);
+      ShouldDiagnoseAvailabilityOfDecl(D, &Message, ClassReceiver);
   if (Result == AR_Available)
     return;
 

clang/lib/Sema/SemaTemplateInstantiate.cpp

@@ -4094,16 +4094,32 @@ bool Sema::InstantiateClassTemplateSpecialization(
   if (ClassTemplateSpec->isInvalidDecl())
     return true;
 
+  bool HadAvaibilityWarning =
+      ShouldDiagnoseAvailabilityOfDecl(ClassTemplateSpec, nullptr, nullptr)
+          .first != AR_Available;
+
   ActionResult<CXXRecordDecl *> Pattern =
       getPatternForClassTemplateSpecialization(*this, PointOfInstantiation,
                                                ClassTemplateSpec, TSK,
                                                PrimaryStrictPackMatch);
+
   if (!Pattern.isUsable())
     return Pattern.isInvalid();
 
-  return InstantiateClass(
+  bool Err = InstantiateClass(
       PointOfInstantiation, ClassTemplateSpec, Pattern.get(),
       getTemplateInstantiationArgs(ClassTemplateSpec), TSK, Complain);
+
+  // If we haven't already warn on avaibility, consider the avaibility
+  // attributes of the partial specialization.
+  // Note that - because we need to have deduced the partial specialization -
+  // We can only emit these warnings when the specialization is instantiated.
+  if (!Err && !HadAvaibilityWarning) {
+    assert(ClassTemplateSpec->getTemplateSpecializationKind() !=
+           TSK_Undeclared);
+    DiagnoseAvailabilityOfDecl(ClassTemplateSpec, PointOfInstantiation);
+  }
+  return Err;
 }
 
 void

clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.deprecated/p1.cpp

@@ -45,7 +45,7 @@ template <typename T> struct [[deprecated]] B;//expected-note {{'B<int>' has bee
 B<int> *q2; // expected-warning {{'B<int>' is deprecated}}
 B<float> *r2; // expected-warning {{'B<float>' is deprecated}}
 
-template <typename T> 
+template <typename T>
 T some_func(T t) {
   struct [[deprecated]] FunS{}; // expected-note {{'FunS' has been explicitly marked deprecated here}}
   FunS f;// expected-warning {{'FunS' is deprecated}}
@@ -72,3 +72,58 @@ template <class B1> struct B {
 
 template struct B<A>; // expected-note {{requested here}}
 } // namespace GH58547
+
+
+namespace GH44496 {
+  template <class> struct my_template {
+    using type = void;
+};
+
+template <class T>
+struct [[deprecated("primary")]] deprecated { // #deprecated-primary-marked-here
+    using type = T;
+};
+
+template <class T>
+struct my_template<volatile T> : deprecated<T> {}; // #deprecated-primary-base
+
+template <class T>
+struct [[deprecated("specialization")]] my_template<const T> : deprecated<const T> {}; // #my_template-explicit-here
+
+
+template <class T> using my_template_t = typename my_template<T>::type; // #deprecated-my-template-alias
+
+// We cannot warn on X because no instantiation has taken place yet
+using X  = my_template<volatile int>;
+
+// Because we already warn on the attribute on the plimary template, we ignore the attribute on the specialization
+using Y  = my_template_t<const int>;
+// expected-warning@#deprecated-primary-base {{'deprecated<int>' is deprecated: primary}} \
+// expected-note@-1 {{in instantiation of template type alias}} \
+// expected-note@#deprecated-primary-marked-here {{has been explicitly marked deprecated here}}
+
+using Z  = my_template_t<volatile int>;
+// expected-warning@#deprecated-my-template-alias {{'my_template<const int>' is deprecated: specialization}} \
+// expected-note@#my_template-explicit-here {{'my_template<const int>' has been explicitly marked deprecated here}} \
+// expected-note@#deprecated-my-template-alias {{in instantiation of template class 'GH44496::my_template<volatile int>' requested here}} \
+// expected-note@-1 {{in instantiation of template type alias 'my_template_t' requested here}}
+
+template <class T>
+struct primary_not_deprecated {
+    using type = T;
+};
+template <class T>
+struct [[deprecated("specialization")]] primary_not_deprecated<volatile T> : deprecated<T> {};
+// expected-note@-1 {{'primary_not_deprecated<volatile int>' has been explicitly marked deprecated here}}
+
+// We cannot warn on S1 because no instantiation has taken place yet
+using S1 = primary_not_deprecated<volatile int>;
+
+
+using S2 = primary_not_deprecated<volatile int>;
+
+X x;
+Z z;
+S2 s2;
+// expected-warning@-1 {{'primary_not_deprecated<volatile int>' is deprecated: specialization}}
+}