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

[Natalie Chouinard via cfe-commits]

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@@ -753,7 +753,10 @@ def err_drv_hlsl_unsupported_target : Error<
   "HLSL code generation is unsupported for target '%0'">;
 def err_drv_hlsl_bad_shader_required_in_target : Error<
   "%select{shader model|Vulkan environment|shader stage}0 is required as %select{OS|environment}1 in target '%2' for HLSL code generation">;
-
+def err_drv_dxc_enable_16bit_types_option_invalid: Error<
+  "enable-16bit-types option only valid when target shader model [-T] is >= 6.2 and HLSL Version [-HV] is >= 2021">;
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sudonatalie wrote:

DXC documentation says `-enable-16bit-types` is allowed in `-HV 2018` (https://github.com/microsoft/DirectXShaderCompiler/wiki/16-Bit-Scalar-Types#dxil-scalar-type). Is this change to 2021 in clang intentional?

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