SKIP: FAILED

[numthreads(1, 1, 1)]
void f() {
  float2x4 a = float2x4(float4(1.0f, 2.0f, 3.0f, 4.0f), float4(5.0f, 6.0f, 7.0f, 8.0f));
  float4x2 b = float4x2(float2(-1.0f, -2.0f), float2(-3.0f, -4.0f), float2(-5.0f, -6.0f), float2(-7.0f, -8.0f));
  float4x4 r = (a * b);
}

DXC validation failure:
hlsl.hlsl:5:21: error: cannot convert from 'float4x2' to 'float2x4'
  float4x4 r = (a * b);
                    ^