Merge commit 'b95cfa401470' from llvm.org/release/21.x into stable/21.x

Author: git apple-llvm automerger

clang/lib/Basic/Targets/OSTargets.h

@@ -174,6 +174,9 @@ class LLVM_LIBRARY_VISIBILITY DragonFlyBSDTargetInfo
     DefineStd(Builder, "unix", Opts);
     if (this->HasFloat128)
       Builder.defineMacro("__FLOAT128__");
+
+    if (Opts.C11)
+      Builder.defineMacro("__STDC_NO_THREADS__");
   }
 
 public:

clang/test/Preprocessor/init.c

@@ -1622,6 +1622,14 @@
 // RUN: %clang_cc1 -x c -std=c99 -E -dM -ffreestanding -triple=amd64-unknown-openbsd < /dev/null | FileCheck -match-full-lines -check-prefix OPENBSD-STDC-N %s
 // OPENBSD-STDC-N-NOT:#define __STDC_NO_THREADS__ 1
 //
+// RUN: %clang_cc1 -x c -std=c11 -E -dM -ffreestanding -triple=x86_64-unknown-dragonfly < /dev/null | FileCheck -match-full-lines -check-prefix DRAGONFLY-STDC %s
+// RUN: %clang_cc1 -x c -std=gnu11 -E -dM -ffreestanding -triple=x86_64-unknown-dragonfly < /dev/null | FileCheck -match-full-lines -check-prefix DRAGONFLY-STDC %s
+// RUN: %clang_cc1 -x c -std=c17 -E -dM -ffreestanding -triple=x86_64-unknown-dragonfly < /dev/null | FileCheck -match-full-lines -check-prefix DRAGONFLY-STDC %s
+// DRAGONFLY-STDC:#define __STDC_NO_THREADS__ 1
+//
+// RUN: %clang_cc1 -x c -std=c99 -E -dM -ffreestanding -triple=x86_64-unknown-dragonfly < /dev/null | FileCheck -match-full-lines -check-prefix DRAGONFLY-STDC-N %s
+// DRAGONFLY-STDC-N-NOT:#define __STDC_NO_THREADS__ 1
+//
 // RUN: %clang_cc1 -triple=aarch64-unknown-managarm-mlibc -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix MANAGARM %s
 // RUN: %clang_cc1 -triple=riscv64-unknown-managarm-mlibc -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix MANAGARM %s
 // RUN: %clang_cc1 -triple=x86_64-unknown-managarm-mlibc -E -dM < /dev/null | FileCheck -match-full-lines -check-prefix MANAGARM %s