move async unsafe fn into #![feature(async_unsafe)]

[delan]

This is my first PR to the project, so please let me know if anything’s amiss!

• tracking issue Tracking issue for #!feature(async_unsafe)] (RFC 2394) #62501
• closes move async unsafe fn to distinct feature gate #62500

r? @Centril

[rust-highfive]

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[Centril]

@delan Thank you for the PR! ❤️

After some discussion, I was convinced not to feature gate this after all (see #62149 (comment)) so I don't think we can merge this PR. I hope this hasn't soured your taste for contributing to rustc and hopefully you got to learn about how to contribute to the compiler.

One thing that is however sorely lacking is tests for async unsafe fn. Would you like to file another PR for that so that we:

• Check that an async unsafe fn requires unsafe { ... } to be called.
  • Including async unsafe fn implementations...
• Tangentially also test the behavior of unsafe { async { $stuff } } wrt. allowing unsafe operations in $stuff.

If you would like, there are some other tests needed that we could use some help with. :)

Thanks again for the PR, and sorry about the noise!

[delan]

After some discussion, I was convinced not to feature gate this after all (see #62149 (comment)) so I don't think we can merge this PR. I hope this hasn't soured your taste for contributing to rustc and hopefully you got to learn about how to contribute to the compiler.

Not at all, these things happen!

One thing that is however sorely lacking is tests for async unsafe fn. Would you like to file another PR for that so that we:

• Check that an async unsafe fn requires unsafe { ... } to be called.
  • Including async unsafe fn implementations...
• Tangentially also test the behavior of unsafe { async { $stuff } } wrt. allowing unsafe operations in $stuff.

I’ll see what I can do about those later today.

Thanks again for the PR, and sorry about the noise!

Happy to help!