HLSL, you little fucker

The bug I was searching for, for a few days now turns out to be a packed uint accidentally stored into a float variable

Not a single peep from the compiler, nothing

It doesn't even have warning flags like -Wconversion

What the fuck. Why microsoft. WHYYY

Hmmm, weird it didn't ring even with conversion warnings enabled.

I've seen such warnings before.

Two things come to mind.

One) you are doing this through some other pipeline, say, ue5, or whatever, that is swallowing the warning.

Two) Microsoft has a (deliberate) bug in saying "if you pack, it's up to you", which is not entirely unreasonable because C compilers are allowed to add arbitrary padding, and I'd bet that would be their excuse.