Proposed fix for PR113152

Author: atrosinenko

clang/lib/Driver/ToolChains/Clang.cpp

@@ -1406,17 +1406,18 @@ static void CollectARMPACBTIOptions(const ToolChain &TC, const ArgList &Args,
     GuardedControlStack = PBP.GuardedControlStack;
   }
 
-  bool HasPtrauthReturns = llvm::any_of(CmdArgs, [](const char *Arg) {
-    return StringRef(Arg) == "-fptrauth-returns";
-  });
+  Arg *PtrauthReturnsArg = Args.getLastArg(options::OPT_fptrauth_returns,
+                                           options::OPT_fno_ptrauth_returns);
+  bool HasPtrauthReturns =
+      PtrauthReturnsArg &&
+      PtrauthReturnsArg->getOption().matches(options::OPT_fptrauth_returns);
   // GCS is currently untested with ptrauth-returns, but enabling this could be
   // allowed in future after testing with a suitable system.
-  if (HasPtrauthReturns &&
-      (Scope != "none" || BranchProtectionPAuthLR || GuardedControlStack)) {
+  if (Scope != "none" || BranchProtectionPAuthLR || GuardedControlStack) {
     if (Triple.getEnvironment() == llvm::Triple::PAuthTest)
       D.Diag(diag::err_drv_unsupported_opt_for_target)
           << A->getAsString(Args) << Triple.getTriple();
-    else
+    else if (HasPtrauthReturns)
       D.Diag(diag::err_drv_incompatible_options)
           << A->getAsString(Args) << "-fptrauth-returns";
   }

clang/test/Frontend/aarch64-ignore-branch-protection-attribute.c

@@ -1,7 +1,11 @@
 // REQUIRES: aarch64-registered-target
 
-// RUN: %clang -target aarch64-linux-pauthtest   %s -S -emit-llvm -o - 2>&1 | FileCheck --implicit-check-not=warning: %s
-// RUN: %clang -target aarch64 -fptrauth-returns %s -S -emit-llvm -o - 2>&1 | FileCheck --implicit-check-not=warning: %s
+// RUN:     %clang -target aarch64-linux-pauthtest   %s -S -emit-llvm -o - 2>&1 | FileCheck --implicit-check-not=warning: %s
+// RUN: not %clang -target aarch64 -fptrauth-returns %s -S -emit-llvm -o - 2>&1 | FileCheck --implicit-check-not=warning: --check-prefix=PTRAUTH-RETURNS %s
+
+// Clang fails early, no LLVM IR output produced.
+// PTRAUTH-RETURNS: clang: error: unsupported option '-fptrauth-returns' for target 'aarch64'
+// PTRAUTH-RETURNS-NOT: attributes
 
 /// Unsupported with pauthtest, warning emitted
 __attribute__((target("branch-protection=pac-ret"))) void f1() {}