[clang] [HLSL] Add validation for the -enable-16bit-types option (PR #85340)

[Natalie Chouinard via cfe-commits]

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@@ -4284,11 +4284,25 @@ bool CompilerInvocation::ParseLangArgs(LangOptions &Opts, ArgList &Args,
           Diags.Report(diag::err_drv_hlsl_bad_shader_unsupported)
               << ShaderModel << T.getOSName() << T.str();
         }
+        // validate that if fnative-half-type is given, that
+        // the language standard is at least hlsl2021, and that
+        // the target shader model is at least 6.2
+        if (Args.getLastArg(OPT_fnative_half_type)) {
+          if (!(Opts.LangStd >= LangStandard::lang_hlsl2021 &&
+                T.getOSVersion() >= VersionTuple(6, 2)))
+            Diags.Report(diag::err_drv_dxc_enable_16bit_types_option_invalid);
+        }
       } else if (T.isSPIRVLogical()) {
         if (!T.isVulkanOS() || T.getVulkanVersion() == VersionTuple(0)) {
           Diags.Report(diag::err_drv_hlsl_bad_shader_unsupported)
               << VulkanEnv << T.getOSName() << T.str();
         }
+        if (Args.getLastArg(OPT_fnative_half_type)) {
+          if (!(Opts.LangStd >= LangStandard::lang_hlsl2021))
+            Diags.Report(
+                diag::err_drv_cc1_hlsl_spirv_fnative_half_type_option_invalid)
+                << VulkanEnv << T.getOSName() << T.str();
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sudonatalie wrote:

Were these extra params left in by mistake?

https://github.com/llvm/llvm-project/pull/85340