"found unregistered decl" when compiling partial template specialization for SPIR-V

Description
Got message with request for new bug report during development for SPIR-V using HLSL 2021 features. Reduced reproduction to a small snippet with partial template specialization.

Steps to Reproduce
Shader Playground link: https://shader-playground.timjones.io/d89cc1395544165f3afe124c26429752
Compiling with -spirv -HV 2021

template <
   bool PARAM1,
   bool PARAM2>
struct TEST_STRUCT{};


template <bool PARAM1>
struct TEST_STRUCT<PARAM1, true> {
   static const bool FIELD = PARAM1;
};

struct PSInput
{
	float4 color : COLOR;
};

float4 PSMain(PSInput input) : SV_TARGET
{
	bool test = TEST_STRUCT<true, true>::FIELD;
	return input.color;
}

Actual Behavior

C:\local\Temp\3c0b2c72-ea2c-4f3d-b4fe-87dad7782596.hlsl:7:16: fatal error: found unregistered decl
template
^
note: please file a bug report on https://github.com/Microsoft/DirectXShaderCompiler/issues with source code if possible

Environment

• DXC version: 1.7 - 1.7.0.3939 (5e080a772)
• Host Operating System: Windows 10/Shader Playground