Require an opt-in for enabling `min_specialization` rustc feature about ahash HOT 4 OPEN

Are you saying that you have a build of the compiler where: version_check::supports_feature("specialize") returns true, but where the feature is not actually supported? Is that a bug in the compiler, in version_check, or an oddity due to running with a custom build of the compiler? Is there a different way to detect this that would not give incorrect results?

Longer term, I am planning a 1.0 release of the crate which will remove all specialization. The current design of the feature makes code using it way too complex and verbose to be practically maintainable. My plan to avoid the performance hit is just to require the application to invoke different methods to instantiate the Builder because in general the type of the key of a map is almost always known at the instantiation site.

Obviously a new version won't affect exiting packages which depend on existing versions of the crate. Do you need a work around for existing package versions?

from ahash.

More-or-less that's the situation yeah. When the build script is invoked in the Rust build system the RUSTFLAGS setting doesn't 100% reflect the flags the crate is going to build with. The build script thinks it has access to all nightly features but the crate itself is compiled with an extra -Zallow-features flag which doesn't actually list the feature. This is due to build-system-of-rust-itself shenanigans and I believe is difficult to change.

As for the time being no workaround is urgent as things have already landed in rust-lang/rust#126967 where extra features were allowed for specialization here. Due to the tool not actually needing specialization or performance wins it would ideally be best to remove the need for specialization to avoid unnecessary dependencies.

from ahash.

Would this fix the detection issue? SergioBenitez/version_check#22

from ahash.

Unfortunately I think not, not because that PR doesn't work though. It's that the compiler flags the build scripts sees are different than the crate itself due to the way the bootstrap build works

from ahash.