Naga 0.20

[Elabajaba]

Pipeline override constants will be fully implemented in a followup PR.

They're theoretically working, but they need tests and also need a function to map the unmangled names to the mangled names.

Otherwise this appears to work. I've tested it with bevy and everything seemed to work.

[Elabajaba]

Discussed this with robtfm on discord, and there seems to be 2 ways forwards for supporting pipeline overridable constants.

1. Mangle them in the shaders, and provide a function that you'd have to use to get the same mangling for them in the rust side code when you pass them into your pipeline descriptors. (seemed to be robtfm's preferred way). This should still let you refer to them by their ids without having to use the mangle function.
2. Don't mangle them, require that they're globally unique (which is what naga_oil's current shader defs require), and add a bunch of checks in the compose module to opt out of mangling them.

[robtfm]

just a couple of minor nits on derive.

i also wanted to keep the prune support so i've done that. i made a pr to your branch with the comment changes and the prune code

[robtfm]

also note - the function to map pipeline const names is already there - Composer::decorated_name does the job.

thanks very much for taking this on.

[Elabajaba]

also note - the function to map pipeline const names is already there - Composer::decorated_name does the job.

thanks very much for taking this on.

🤦

[JMS55]

Haven't actually tested subgroups/pipeline overrides, but approving it conditional on it working. I'll have to hook this up to bevy and try it out when I'm next free.

[IceSentry]

I haven't seen anything obviously wrong in the code and I tested it with almost all 2d and 3d examples with no issues. So LGTM