Fix build failure on nightly and the minimum version

[taiki-e]

target_has_atomic = "cas" was removed in rust-lang/rust#65214.

Fixes rust-lang/rust#65424
Fixes #412

[jeehoonkang]

Thanks!

bors r+

[bors]

Build failed

• continuous-integration/travis-ci/push

[taiki-e]

@jeehoonkang Since the build on Rust 1.26 is broken, I think we need to merge this and #429 at the same time.

[jeehoonkang]

Thanks for updating the dependency.

bors r+

[jeehoonkang]

CI fails with permission error: https://travis-ci.org/crossbeam-rs/crossbeam/jobs/598198019#L203

[jeehoonkang]

Thinking again, downgrading only for CI looks suspicious. Then CI can only tell a modified Crossbeam (with different dependency) compiles for Rust 1.26, but not Crossbeam as-is. I think it may not be what we want... Do you know how Rayon deals with such a situation?

[bors]

Build failed

• continuous-integration/travis-ci/push

[taiki-e]

Thinking again, downgrading only for CI looks suspicious. Then CI can only tell a modified Crossbeam (with different dependency) compiles for Rust 1.26, but not Crossbeam as-is. I think it may not be what we want... Do you know how Rayon deals with such a situation?

I think the following comments accurately explain the current situation (using an old Cargo.lock):

rayon-rs/rayon#586 (comment)

The state of the ecosystem is that, for better or worse, any less-than-latest Rust version is not supported in general, and in practice absolutely unusable without an old Cargo.lock. Debian's Rust is just totally useless.

Also, they recently bumped the minimum version to 1.28 (rayon-rs/rayon#675), so I think we can drop 1.26 and 1.27's support.

Edit: see rayon-rs/rfcs#3 for rayon's a minimum Rust policy

[taiki-e]

@jeehoonkang CI passed.

[jeehoonkang]

I'm fine with this change, I'd like to wait for another approval because it's changing the CI policy. @Vtec234 @stjepang Any thoughts?

[ghost]

Let's drop support for 1.26 and 1.27.

[taiki-e]

Added commit to drop support for 1.26 and 1.27. Also, since the minimum version is 1.28, we can revert #393 and fix bare_trait_objects warnings.

[taiki-e]

Oh... deprecated warnings...

error: use of deprecated item 'std::mem::uninitialized': use `mem::MaybeUninit` instead
  --> crossbeam-epoch/src/deferred.rs:39:38
   |
39 |                 let mut data: Data = mem::uninitialized();
   |                                      ^^^^^^^^^^^^^^^^^^
   |
   = note: `-D deprecated` implied by `-D warnings`

I will use #[allow(deprecated)] because the alternative requires 1.36.

[jeehoonkang]

Thanks!

bors retry

[bors]

Build failed

• continuous-integration/travis-ci/push

[jeehoonkang]

bors retry

[bors]

Build succeeded

• continuous-integration/travis-ci/push