rustc 1.100

[Firestar99]

• @nazar-pc specifically requested nightly-2026-09-05 in spirv-std-nightly crate to enable adt_const_params use #636 (comment), so we have one commit doing exactly that
• our compiletest infra broke, no idea if this commit even works

[nazar-pc]

nightly-2026-09-06 is the first broken version (#project-const-generics > nightly-2026-09-06 generic const regression), nightly-2026-09-05 is the last one that works

[Firestar99]

Moved it back by a day.

If you're curious how I update toolchains:

• cargo xtask set-toolchain [2026-09-05] (omitting the date will choose today' nightly)
• fix compile errors in cargo b -p rustc_codegen_spirv, most of the time it's small API changes that don't really affect rust-gpu, like in this PR
• cargo compiletest to see if any emission changed. AI is surprisingly good at finding the rustc commit that broke us.

[Firestar99]

Blocker for merge: Not sure if we want to release 1.99 on it's own or merge this and then release.
(and I can't block my own PR from getting merged, cause github doesn't allow you to request changes when you've opened the PR...)

[nazar-pc]

I hope you release 1.99.0 separately. I'll not be able to upgrade to anything newer for now, so having a choice would be nice. I can use it from Git too, but release is cleaner.