.mips operator function not supported Texture2D

[chaoticbob]

The shader below fails to compile using slangc (52b5bb4):

$ slangc -target spirv -emit-spirv-directly -lang slang -profile cs_6_0 -entry csmain texture2d_mips.slang
texture2d_mips.slang(19): error 30027: 'mips' is not a member of 'Texture2D<float>'.
    Dst[0] = Src.mips[2][g_PixelReadback.pixelPosition.xy];

Shader source

struct PixelReadbackConstants
{
    int2    pixelPosition;
    int2    dummy;
};

cbuffer c_PixelReadback : register(b0)
{
    PixelReadbackConstants g_PixelReadback;
};

Texture2D<float> Src : register(t1);
RWBuffer<float>  Dst : register(u2);

[shader("compute")]
[numthreads(1, 1, 1)]
void csmain()
{
    Dst[0] = Src.mips[2][g_PixelReadback.pixelPosition.xy];
}

DXC emits the below SPIR-V for the above shader when targeting Vulkan 1.3:

; SPIR-V
; Version: 1.6
; Generator: Google spiregg; 0
; Bound: 32
; Schema: 0
               OpCapability Shader
               OpCapability SampledBuffer
               OpCapability ImageBuffer
               OpCapability StorageImageReadWithoutFormat
               OpMemoryModel Logical GLSL450
               OpEntryPoint GLCompute %csmain "csmain" %c_PixelReadback %Src %Dst
               OpExecutionMode %csmain LocalSize 1 1 1
               OpSource HLSL 600
               OpName %type_c_PixelReadback "type.c_PixelReadback"
               OpMemberName %type_c_PixelReadback 0 "g_PixelReadback"
               OpName %PixelReadbackConstants "PixelReadbackConstants"
               OpMemberName %PixelReadbackConstants 0 "pixelPosition"
               OpMemberName %PixelReadbackConstants 1 "dummy"
               OpName %c_PixelReadback "c_PixelReadback"
               OpName %type_2d_image "type.2d.image"
               OpName %Src "Src"
               OpName %type_buffer_image "type.buffer.image"
               OpName %Dst "Dst"
               OpName %csmain "csmain"
               OpDecorate %c_PixelReadback DescriptorSet 0
               OpDecorate %c_PixelReadback Binding 0
               OpDecorate %Src DescriptorSet 0
               OpDecorate %Src Binding 1
               OpDecorate %Dst DescriptorSet 0
               OpDecorate %Dst Binding 2
               OpMemberDecorate %PixelReadbackConstants 0 Offset 0
               OpMemberDecorate %PixelReadbackConstants 1 Offset 8
               OpMemberDecorate %type_c_PixelReadback 0 Offset 0
               OpDecorate %type_c_PixelReadback Block
       %uint = OpTypeInt 32 0
     %uint_2 = OpConstant %uint 2
        %int = OpTypeInt 32 1
      %int_0 = OpConstant %int 0
     %uint_0 = OpConstant %uint 0
      %v2int = OpTypeVector %int 2
%PixelReadbackConstants = OpTypeStruct %v2int %v2int
%type_c_PixelReadback = OpTypeStruct %PixelReadbackConstants
%_ptr_Uniform_type_c_PixelReadback = OpTypePointer Uniform %type_c_PixelReadback
      %float = OpTypeFloat 32
%type_2d_image = OpTypeImage %float 2D 2 0 0 1 Unknown
%_ptr_UniformConstant_type_2d_image = OpTypePointer UniformConstant %type_2d_image
%type_buffer_image = OpTypeImage %float Buffer 2 0 0 2 R32f
%_ptr_UniformConstant_type_buffer_image = OpTypePointer UniformConstant %type_buffer_image
       %void = OpTypeVoid
         %20 = OpTypeFunction %void
%_ptr_Uniform_v2int = OpTypePointer Uniform %v2int
     %v2uint = OpTypeVector %uint 2
    %v4float = OpTypeVector %float 4
%c_PixelReadback = OpVariable %_ptr_Uniform_type_c_PixelReadback Uniform
        %Src = OpVariable %_ptr_UniformConstant_type_2d_image UniformConstant
        %Dst = OpVariable %_ptr_UniformConstant_type_buffer_image UniformConstant
     %csmain = OpFunction %void None %20
         %24 = OpLabel
         %25 = OpAccessChain %_ptr_Uniform_v2int %c_PixelReadback %int_0 %int_0
         %26 = OpLoad %v2int %25
         %27 = OpBitcast %v2uint %26
         %28 = OpLoad %type_2d_image %Src
         %29 = OpImageFetch %v4float %28 %27 Lod %uint_2
         %30 = OpCompositeExtract %float %29 0
         %31 = OpLoad %type_buffer_image %Dst
               OpImageWrite %31 %uint_0 %30 None
               OpReturn
               OpFunctionEnd

[ArielG-NV]

Note: requires deciding how we want to implement subscript operators on property like type's (new getter, embedding __subscript in a property, etc.)