Changes after @ojhunt's review on 2025-09-09 (#157779)

Author: martinuy

clang/include/clang/AST/ASTContext.h

@@ -659,6 +659,11 @@ class ASTContext : public RefCountedBase<ASTContext> {
     return findPointerAuthContent(T) != PointerAuthContent::None;
   }
 
+  // A simple helper function to short circuit pointer auth checks.
+  bool isPointerAuthenticationAvailable() const {
+    return LangOpts.PointerAuthCalls || LangOpts.PointerAuthIntrinsics;
+  }
+
 private:
   llvm::DenseMap<const CXXRecordDecl *, CXXRecordDeclRelocationInfo>
       RelocatableClasses;
@@ -670,10 +675,6 @@ class ASTContext : public RefCountedBase<ASTContext> {
     AddressDiscriminatedData
   };
 
-  // A simple helper function to short circuit pointer auth checks.
-  bool isPointerAuthenticationAvailable() const {
-    return LangOpts.PointerAuthCalls || LangOpts.PointerAuthIntrinsics;
-  }
   PointerAuthContent findPointerAuthContent(QualType T) const;
   mutable llvm::DenseMap<const RecordDecl *, PointerAuthContent>
       RecordContainsAddressDiscriminatedPointerAuth;

clang/include/clang/Basic/DiagnosticGroups.td

@@ -1072,7 +1072,6 @@ def GNUZeroLineDirective : DiagGroup<"gnu-zero-line-directive">;
 def GNUZeroVariadicMacroArguments : DiagGroup<"gnu-zero-variadic-macro-arguments", [VariadicMacroArgumentsOmitted]>;
 def MisleadingIndentation : DiagGroup<"misleading-indentation">;
 def PtrAuthNullPointers : DiagGroup<"ptrauth-null-pointers">;
-def PtrAuthWeakSchema : DiagGroup<"ptrauth-weak-schema">;
 
 // This covers both the deprecated case (in C++98)
 // and the extension case (in C++11 onwards).

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -1047,9 +1047,10 @@ def err_ptrauth_extra_discriminator_invalid : Error<
   "invalid extra discriminator flag '%0'; '__ptrauth' requires a value between "
   "'0' and '%1'">;
 def warn_ptrauth_weak_schema
-    : Warning<"internal variable %0 is using a weak signing schema for pointer "
-              "authentication">,
-      InGroup<PtrAuthWeakSchema>;
+    : Warning<"%0 has internal linkage with a %select{|default }1"
+              "pointer authentication schema that should be overridden by "
+              "%select{a|an explicit}1 schema with unique diversifiers">,
+      InGroup<DiagGroup<"ptrauth-weak-schema">>;
 
 /// main()
 // static main() is not an error in C, just in C++.

clang/lib/Sema/SemaDecl.cpp

@@ -8359,11 +8359,13 @@ NamedDecl *Sema::ActOnVariableDeclarator(
 
   // Warn about the use of a weak pointer authentication schema on a variable
   // with internal linkage.
-  if (getLangOpts().PointerAuthCalls && NewVD->isFunctionPointerType() &&
-      !isExternallyVisible(NewVD->getLinkageInternal())) {
+  if (Context.isPointerAuthenticationAvailable() &&
+      NewVD->isFunctionPointerType() && !NewVD->isExternallyVisible()) {
     PointerAuthQualifier Q = NewVD->getType().getQualifiers().getPointerAuth();
-    if (!Q || (!Q.isAddressDiscriminated() && Q.getExtraDiscriminator() == 0))
-      Diag(NewVD->getLocation(), diag::warn_ptrauth_weak_schema) << NewVD;
+    if (!Q || (!Q.isAddressDiscriminated() && Q.getExtraDiscriminator() == 0)) {
+      Diag(NewVD->getLocation(), diag::warn_ptrauth_weak_schema)
+          << NewVD << (Q ? 0 : 1);
+    }
   }
 
   if (NewTemplate) {

clang/test/Sema/ptrauth-weak-schema.c

@@ -1,23 +1,16 @@
-// RUN: %clang_cc1 -triple arm64e-apple-ios -fptrauth-calls -fptrauth-intrinsics -fsyntax-only -verify %s
-// RUN: %clang_cc1 -triple arm64e-apple-ios -DNO_PTRAUTH -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple arm64e-apple-ios -fptrauth-calls -fptrauth-intrinsics -fsyntax-only -Wno-unused-variable -verify %s
+// RUN: %clang_cc1 -triple arm64e-apple-ios -DNO_PTRAUTH -fsyntax-only -Wno-unused-variable -verify=noptrauth %s
 
-#if defined(NO_PTRAUTH)
-
-#define FN_PTR_AUTH(address_diversity, constant_discriminator)
-// expected-no-diagnostics
-
-#else // !defined(NO_PTRAUTH)
-
-#if !__has_extension(ptrauth_qualifier)
-#error __ptrauth qualifier not enabled
-#endif
+// noptrauth-no-diagnostics
 
 #include <ptrauth.h>
 
+#if defined(NO_PTRAUTH)
+#define FN_PTR_AUTH(address_diversity, constant_discriminator)
+#else
 #define FN_PTR_AUTH(address_diversity, constant_discriminator) \
   __ptrauth(ptrauth_key_function_pointer, address_diversity, constant_discriminator)
-
-#endif // defined(NO_PTRAUTH)
+#endif
 
 // Global variables with external linkage and weak pointer authentication should
 // not raise any warning.
@@ -34,9 +27,9 @@ static void(* FN_PTR_AUTH(1, 0) g3_internal_strong)(void);
 // Global variables with internal linkage and weak pointer authentication should
 // raise a warning.
 static void(* g1_internal_weak)(void);
-// expected-warning@-1 {{internal variable 'g1_internal_weak' is using a weak signing schema for pointer authentication}}
+// expected-warning@-1 {{'g1_internal_weak' has internal linkage with a default pointer authentication schema that should be overridden by an explicit schema with unique diversifiers}}
 static void(* FN_PTR_AUTH(0, 0) g2_internal_weak)(void);
-// expected-warning@-1 {{internal variable 'g2_internal_weak' is using a weak signing schema for pointer authentication}}
+// expected-warning@-1 {{'g2_internal_weak' has internal linkage with a pointer authentication schema that should be overridden by a schema with unique diversifiers}}
 
 // Assert that -Wptrauth-weak-schema silences warnings.
 #pragma clang diagnostic push
@@ -46,23 +39,18 @@ static void(* g3_internal_weak)(void);
 #endif
 
 void test_local_variables(void) {
-    #pragma clang diagnostic push
-    #pragma clang diagnostic ignored "-Wunused-variable"
-
     #if !defined(NO_PTRAUTH)
     // Local variables (internal linkage) with weak pointer authentication
     // should raise a warning.
     static void(* l1_internal_weak)(void);
-    // expected-warning@-1 {{internal variable 'l1_internal_weak' is using a weak signing schema for pointer authentication}}
+    // expected-warning@-1 {{'l1_internal_weak' has internal linkage with a default pointer authentication schema that should be overridden by an explicit schema with unique diversifiers}}
     static void(* FN_PTR_AUTH(0, 0) l2_internal_weak)(void);
-    // expected-warning@-1 {{internal variable 'l2_internal_weak' is using a weak signing schema for pointer authentication}}
+    // expected-warning@-1 {{'l2_internal_weak' has internal linkage with a pointer authentication schema that should be overridden by a schema with unique diversifiers}}
     #endif
 
     // Local variables (internal linkage) with strong pointer authentication
     // should not raise any warning.
     void(* FN_PTR_AUTH(1, 65535) l1_internal_strong)(void);
     void(* FN_PTR_AUTH(0, 65535) l2_internal_strong)(void);
     void(* FN_PTR_AUTH(1, 0) l3_internal_strong)(void);
-
-    #pragma clang diagnostic pop
 }