add test and comment in response to feedback

Author: spall

clang/include/clang/Driver/Options.td

@@ -8630,6 +8630,7 @@ def vtordisp_mode_EQ : Joined<["-"], "vtordisp-mode=">,
   MarshallingInfoInt<LangOpts<"VtorDispMode">, "1">;
 def fnative_int16_type : Flag<["-"], "fnative-int16-type">,
   HelpText<"Use 16 bit integer types">,
+  // This option is implied unless we are in HLSL lang mode
   ImpliedByAnyOf<[!strconcat("!", hlsl.KeyPath)]>,
   MarshallingInfoFlag<LangOpts<"NativeInt16Type">>;
 def fnative_half_type: Flag<["-"], "fnative-half-type">,

clang/test/Options/enable_16bit_types_validation_spirv.hlsl

@@ -1,7 +1,9 @@
-// RUN: not %clang_cc1 -internal-isystem D:\llvm-project\build\x64-Release\lib\clang\19\include -nostdsysteminc -triple spirv-vulkan-library -x hlsl -std=hlsl2016 -fnative-half-type -emit-llvm -disable-llvm-passes  -o - %s 2>&1 | FileCheck %s --check-prefix=SPIRV
-// RUN: %clang_cc1 -internal-isystem D:\llvm-project\build\x64-Release\lib\clang\19\include -nostdsysteminc -triple spirv-vulkan-library -x hlsl -std=hlsl2021 -fnative-half-type -emit-llvm -disable-llvm-passes  -o - %s 2>&1 | FileCheck %s --check-prefix=valid
+// RUN: not %clang_cc1 -internal-isystem D:\llvm-project\build\x64-Release\lib\clang\19\include -nostdsysteminc -triple spirv-vulkan-library -x hlsl -std=hlsl2016 -fnative-half-type -emit-llvm -disable-llvm-passes  -o - %s 2>&1 | FileCheck %s --check-prefix=SPIRV-HALF
+// RUN: not %clang_cc1 -internal-isystem D:\llvm-project\build\x64-Release\lib\clang\19\include -nostdsysteminc -triple spirv-vulkan-library -x hlsl -std=hlsl2016 -fnative-int16-type -emit-llvm -disable-llvm-passes  -o - %s 2>&1 | FileCheck %s --check-prefix=SPIRV-INT
+// RUN: %clang_cc1 -internal-isystem D:\llvm-project\build\x64-Release\lib\clang\19\include -nostdsysteminc -triple spirv-vulkan-library -x hlsl -std=hlsl2021 -fnative-half-type -fnative-int16-type -emit-llvm -disable-llvm-passes  -o - %s 2>&1 | FileCheck %s --check-prefix=valid
 
-// SPIRV: error: '-fnative-half-type' option requires target HLSL Version >= 2018, but HLSL Version is 'hlsl2016'
+// SPIRV-HALF: error: '-fnative-half-type' option requires target HLSL Version >= 2018, but HLSL Version is 'hlsl2016'
+// SPIRV-INT: error: '-fnative-int16-type' option requires target HLSL Version >= 2018, but HLSL Version is 'hlsl2016'
 
 // valid: "spirv-unknown-vulkan-library"
 // valid: define hidden spir_func void @{{.*main.*}}() #0 {