unrecognized platform-specific intrinsic function

[Mark-Simulacrum]

A set of intrinsics are no longer present it seems (perhaps in LLVM?); see log in https://crater-reports.s3.amazonaws.com/beta-1.33-1/beta-2019-01-22/reg/basic_dsp-0.6.0/log.txt.

cc @rust-lang/libs @liebharc

[hanna-kruppe]

This is an unstable feature removed in #57416. It appears the simd crate (which basic_dsp uses) sets RUSTC_BOOTSTRAP to use unstable features on stable/beta ☹️

[liebharc]

For basic_dsp users: simd is an optional dependency of basic_dsp. So as a workaround people should still be able to compile it with --no-default-features --std.

At the time basic_dsp was created the simd crate was the only explicit SIMD support in Rust. I haven't followed SIMD development in Rust that closely in the last year, but it seems that there are alternatives to simd. So that would be a possibility for me to address this.

Please let me know how you would like to proceed with this issue.

[alexcrichton]

Looks like @rkruppe is right and I believe the bug here is not in @liebharc's basic_dsp crater but rather the dependency on simd. Setting RUSTC_BOOTSTRAP is definitely not covered by our stability policy, which I believe is already known, so I'm going to close this.

[alexcrichton]

@liebharc in the meantime if you'd like to remove the dependency on simd the recommendations are:

• Ideally use std::arch if functionality is already implemented there
• If you're willing and it's not there, add such functionality to std::arch via the stdsimd repository
• Falling back to inline assembly compiled assembly via the cc crate
• If none of that is appropriate, using simd but understanding that it's nightly only for now