[pixel shader]

float2 max(float2 a, float2 b)
{
    return a + b;
}

float4 main() : sv_target
{
    return float4(max(0.1, 0.2), max(float2(0.1, 0.2), float2(0.3, 0.4)));
}

[test]
draw quad
probe all rgba (0.3, 0.3, 0.4, 0.6)

[pixel shader]

float2 max(float2 a, float3 b)
{
    return a + b.xy;
}

float4 main() : sv_target
{
    return float4(max(0.1, 0.2), max(float2(0.1, 0.2), float2(0.3, 0.4)));
}

[test]
draw quad
probe all rgba (0.3, 0.3, 0.3, 0.4)