spirv-std 0.8.0 & 0.9.0 fail to compile rustc-codegen-spirv #123
Description
cargo-gpu fails to compile spirv-std 0.8.0 & 0.9.0 with this error:
error: package `indexmap v2.12.0` cannot be built because it requires rustc 1.82 or newer, while the currently active rustc version is 1.70.0-nightly
Either upgrade to rustc 1.82 or newer, or use
cargo update -p [email protected] --precise ver
where `ver` is the latest version of `indexmap` supporting rustc 1.70.0-nightly
Cause
indexmap released version 2.12.0 (which cargo update automatically updates to) with the breaking change:
MSRV: Rust 1.82.0 or later is now required.
spirv-std 0.8.0 & 0.9.0 use a too old rustc version.
$ cargo tree -i [email protected]
indexmap v2.12.0
└── elsa v1.11.2
└── spirt v0.2.0
└── rustc_codegen_spirv v0.8.0
└── rustc_codegen_spirv_dummy v0.1.0 (/home/firestar99/.cache/rust-gpu/codegen/0_8_0)
Resolution Options
Update spirv-std
Update spirv-std to 0.8.1 / 0.9.1 that fixes indexmap version to 0.11.4
Fix within cargo-gpu
We could add indexmap = "=0.11.4" to the rustc-codegen-spirv_dummy project that cargo-gpu creates to compile rustc-codegen-spirv. But that may break future rustc-codegen-spirv versions, so we need to limit it to old versions. Which is not super easy to detect, I could imagine somehow integrating it into the target_specs not detecting any target-specs being delivered, but it's kinda hacky.
Drop support for those old versions
I thought of redoing target_specs anyway to not have to distribute them as files but generate them on the fly. And potentially dropping all old versions to cleanup the cargo-gpu codebase a bit.
Lockfile support
Distribute rustc-codegen-spirv with a lockfile and use it, similarly to how cargo install --locked does it. May take more time to implement and may not be viable with older versions, haven't checked.