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

[Joshua Batista via cfe-commits]

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@@ -4284,11 +4284,31 @@ 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 hlsl2018, and that
+        // the target shader model is at least 6.2.
+        if (Args.getLastArg(OPT_fnative_half_type)) {
+          const LangStandard &Std =
+              LangStandard::getLangStandardForKind(Opts.LangStd);
+          if (!(Opts.LangStd >= LangStandard::lang_hlsl2018 &&
+                T.getOSVersion() >= VersionTuple(6, 2)))
+            Diags.Report(diag::err_drv_hlsl_16bit_types_unsupported)
+                << "-enable-16bit-types" << true << Std.getName()
+                << T.getOSVersion().getAsString();
+        }
       } 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)) {
+          const LangStandard &Std =
+              LangStandard::getLangStandardForKind(Opts.LangStd);
+          if (!(Opts.LangStd >= LangStandard::lang_hlsl2018))
+            Diags.Report(diag::err_drv_hlsl_16bit_types_unsupported)
+                << "-fnative-half-type" << false << Std.getName()
+                << T.getOSVersion().getAsString();
----------------
bob80905 wrote:

I need that last parameter to the report function because that supplies the shader model information. It can indicate to the user whether or not the shader model is too low or high enough. The diagnostic uses parameters %0 - %3, so I do need 4 parameters.

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