Iterator variables shouldn't "leak" out of for-loops

[Jasper-Bekkers]

http://shader-playground.timjones.io/9ec140c1a4f17799769abb8a333f4986

void stuff(out float3 b) {
    for(int i = 0; i < 10; i++) {
    }
    
    b = i;
}

I think these are legacy HLSL rules, but in any modern programming language with reasonable scoping rules this shouldn't compile. I think we shouldn't expect DXC to accept this code.

[jaebaek]

@pow2clk Oops .. this is an interesting bug. I am curious the for-loop is the only case or it can happen in other cases as well.

[pow2clk]

Hi @Jasper-Bekkers,

We have to blame the gravity of legacy for this one. This is how HLSL has behaved since its inception. We considered this change for HLSL 2021, but decided it was a more impactful change than we were willing to make at this time. We will likely consider it again for the next HLSL version.

It is a known issue. In fact, a much older bug #584 is already tracking this. As such, I'm closing this as a duplicate.