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Libc on osx now requires rust 1.24.0+ #1232

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erickt opened this issue Jan 29, 2019 · 6 comments
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Libc on osx now requires rust 1.24.0+ #1232

erickt opened this issue Jan 29, 2019 · 6 comments

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@erickt
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erickt commented Jan 29, 2019

The rand crate tries to maintain compatibility with rust 1.22.0, but a recent release of libc now implicitly requires 1.24.0 on osx due to this patch: #1212, which uses a constant function that was stablized in 1.24. It appears that the Travis config is trying to maintain compatibility with 1.13, but this test only runs on Linux.

Now I personally don't care what is the minimum version you want to support, but given how libc is now the most actively used dependency, you drive the minimum version of a lot of the ecosystem, so would it be possible to at least document this requirement, or setup some more test targets to make sure this doesn't happen again accidentally?
@gnzlbg
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gnzlbg commented Jan 29, 2019 •
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@erickt thank you for the report and sorry for the inconvenience.

We should:

  • detect whether the Rust version is >= 1.24 in our build.rs file, and define a cfg flag that is used to white-list const fns in those cases. The functions can be exposed as non-const fn in older Rust versions (or not at all).

  • run cargo build for nightly, beta, and stable, on all build bots using Rust 1.13 as the stable Rust version

I can look into implementing both of these things.

@gnzlbg gnzlbg mentioned this issue Jan 29, 2019
Closed
gnzlbg added a commit to gnzlbg/libc that referenced this issue Feb 7, 2019
@gnzlbg
Fix build on all platforms
b5a98ca 
This PR fixes the build on all platforms and all Rust version down to the
minimum Rust version supported by libc: Rust 1.13.0.

The `build.rs` is extended with logic to detect the newer Rust features used by
`libc` since Rust 1.13.0:

* Rust 1.19.0: `untagged_unions`. APIs using untagged unions are gated on
  `cfg(libc_unions)` and not available on older Rust versions.

* Rust 1.25.0: `repr(align)`. Because `repr(align)` cannot be parsed by older
  Rust versions, all uses of `repr(align)` are split into `align.rs` and
  `no_align.rs` modules, which are gated on the `cfg(libc_align)` at the top
  level. These modules sometimes contain macros that are expanded at the top
  level to avoid privacy issues (`pub(crate)` is not available in older Rust
  versions). Closes rust-lang#1242 .

* Rust : `const` `mem::size_of`. These uses are worked around with hardcoded
  constants on older Rust versions.

Also, `repr(packed)` structs cannot automatically `derive()` some traits like
`Debug`. These have been moved into `s_no_extra_traits!` and the lint of missing
`Debug` implementations on public items is silenced for these. We can manually
implement the `extra_traits` for these in a follow up PR. This is tracked in

Since `f64::to_bits` is not available in older Rust versions, its usage
has been replaced with a `transmute` to an `u64` which is what that method
does under the hood.

Closes rust-lang#1232 .
gnzlbg added a commit to gnzlbg/libc that referenced this issue Feb 7, 2019
@gnzlbg
Fix build on all platforms
bdf4e73 
This PR fixes the build on all platforms and all Rust version down to the
minimum Rust version supported by libc: Rust 1.13.0.

The `build.rs` is extended with logic to detect the newer Rust features used by
`libc` since Rust 1.13.0:

* Rust 1.19.0: `untagged_unions`. APIs using untagged unions are gated on
  `cfg(libc_unions)` and not available on older Rust versions.

* Rust 1.25.0: `repr(align)`. Because `repr(align)` cannot be parsed by older
  Rust versions, all uses of `repr(align)` are split into `align.rs` and
  `no_align.rs` modules, which are gated on the `cfg(libc_align)` at the top
  level. These modules sometimes contain macros that are expanded at the top
  level to avoid privacy issues (`pub(crate)` is not available in older Rust
  versions). Closes rust-lang#1242 .

* Rust : `const` `mem::size_of`. These uses are worked around with hardcoded
  constants on older Rust versions.

Also, `repr(packed)` structs cannot automatically `derive()` some traits like
`Debug`. These have been moved into `s_no_extra_traits!` and the lint of missing
`Debug` implementations on public items is silenced for these. We can manually
implement the `extra_traits` for these in a follow up PR. This is tracked in

Since `f64::to_bits` is not available in older Rust versions, its usage
has been replaced with a `transmute` to an `u64` which is what that method
does under the hood.

Closes rust-lang#1232 .
gnzlbg added a commit to gnzlbg/libc that referenced this issue Feb 7, 2019
@gnzlbg
Fix build on all platforms
a406fe6 
This PR fixes the build on all platforms and all Rust version down to the
minimum Rust version supported by libc: Rust 1.13.0.

The `build.rs` is extended with logic to detect the newer Rust features used by
`libc` since Rust 1.13.0:

* Rust 1.19.0: `untagged_unions`. APIs using untagged unions are gated on
  `cfg(libc_unions)` and not available on older Rust versions.

* Rust 1.25.0: `repr(align)`. Because `repr(align)` cannot be parsed by older
  Rust versions, all uses of `repr(align)` are split into `align.rs` and
  `no_align.rs` modules, which are gated on the `cfg(libc_align)` at the top
  level. These modules sometimes contain macros that are expanded at the top
  level to avoid privacy issues (`pub(crate)` is not available in older Rust
  versions). Closes rust-lang#1242 .

* Rust : `const` `mem::size_of`. These uses are worked around with hardcoded
  constants on older Rust versions.

Also, `repr(packed)` structs cannot automatically `derive()` some traits like
`Debug`. These have been moved into `s_no_extra_traits!` and the lint of missing
`Debug` implementations on public items is silenced for these. We can manually
implement the `extra_traits` for these in a follow up PR. This is tracked
in rust-lang#1243. Also, `extra_traits` does not enable `align` manually anymore.

Since `f64::to_bits` is not available in older Rust versions, its usage
has been replaced with a `transmute` to an `u64` which is what that method
does under the hood.

Closes rust-lang#1232 .
gnzlbg added a commit to gnzlbg/libc that referenced this issue Feb 7, 2019
@gnzlbg
Fix build on all platforms
072403d 
This PR fixes the build on all platforms and all Rust version down to the
minimum Rust version supported by libc: Rust 1.13.0.

The `build.rs` is extended with logic to detect the newer Rust features used by
`libc` since Rust 1.13.0:

* Rust 1.19.0: `untagged_unions`. APIs using untagged unions are gated on
  `cfg(libc_unions)` and not available on older Rust versions.

* Rust 1.25.0: `repr(align)`. Because `repr(align)` cannot be parsed by older
  Rust versions, all uses of `repr(align)` are split into `align.rs` and
  `no_align.rs` modules, which are gated on the `cfg(libc_align)` at the top
  level. These modules sometimes contain macros that are expanded at the top
  level to avoid privacy issues (`pub(crate)` is not available in older Rust
  versions). Closes rust-lang#1242 .

* Rust : `const` `mem::size_of`. These uses are worked around with hardcoded
  constants on older Rust versions.

Also, `repr(packed)` structs cannot automatically `derive()` some traits like
`Debug`. These have been moved into `s_no_extra_traits!` and the lint of missing
`Debug` implementations on public items is silenced for these. We can manually
implement the `extra_traits` for these in a follow up PR. This is tracked
in rust-lang#1243. Also, `extra_traits` does not enable `align` manually anymore.

Since `f64::to_bits` is not available in older Rust versions, its usage
has been replaced with a `transmute` to an `u64` which is what that method
does under the hood.

Closes rust-lang#1232 .
gnzlbg added a commit to gnzlbg/libc that referenced this issue Feb 7, 2019
@gnzlbg
Fix build on all platforms
c934678 
This PR fixes the build on all platforms and all Rust version down to the
minimum Rust version supported by libc: Rust 1.13.0.

The `build.rs` is extended with logic to detect the newer Rust features used by
`libc` since Rust 1.13.0:

* Rust 1.19.0: `untagged_unions`. APIs using untagged unions are gated on
  `cfg(libc_unions)` and not available on older Rust versions.

* Rust 1.25.0: `repr(align)`. Because `repr(align)` cannot be parsed by older
  Rust versions, all uses of `repr(align)` are split into `align.rs` and
  `no_align.rs` modules, which are gated on the `cfg(libc_align)` at the top
  level. These modules sometimes contain macros that are expanded at the top
  level to avoid privacy issues (`pub(crate)` is not available in older Rust
  versions). Closes rust-lang#1242 .

* Rust : `const` `mem::size_of`. These uses are worked around with hardcoded
  constants on older Rust versions.

Also, `repr(packed)` structs cannot automatically `derive()` some traits like
`Debug`. These have been moved into `s_no_extra_traits!` and the lint of missing
`Debug` implementations on public items is silenced for these. We can manually
implement the `extra_traits` for these in a follow up PR. This is tracked
in rust-lang#1243. Also, `extra_traits` does not enable `align` manually anymore.

Since `f64::to_bits` is not available in older Rust versions, its usage
has been replaced with a `transmute` to an `u64` which is what that method
does under the hood.

Closes rust-lang#1232 .
@Stebalien Stebalien mentioned this issue Feb 8, 2019
Merged
@bors bors closed this as completed in a17a91c Feb 8, 2019
@gnzlbg
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gnzlbg commented Feb 8, 2019

cc @Stebalien @erickt libc mater builds again down to Rust 1.13. There are a couple of PRs with fixes in the queue. Once those are merged I'll do a new release.

@gnzlbg
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gnzlbg commented Feb 8, 2019

I forgot to mention what I wanted to mention. Would you be able to test if the master branch solves your issues ? (e.g. by creating a PR to your projects that use the libc master branch and letting your CI run?).

@dhardy
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dhardy commented Feb 15, 2019

We still appear to have a problem using Rustc 1.22 on OSX: https://travis-ci.org/rust-random/rand/jobs/493719761 (use of mem::size_of as a const fn). Is this because the relevant changes are not in a release yet?

I don't have a Mac platform to test with myself.
See also: rust-random/rand#719

@dhardy dhardy mentioned this issue Feb 15, 2019
Merged
@gnzlbg
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gnzlbg commented Feb 15, 2019

Is this because the relevant changes are not in a release yet?

Yes. The changes are on master, and a release is blocked on the affected parties testing that master does not have these issues.

@dhardy
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dhardy commented Feb 15, 2019 •
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Okay, I forced Travis to use libc master via a patch section. The test now succeeds on OSX with Rustc 1.22.0 where it didn't before. So seems to have fixed it.

Edit: see this PR. I will remove the extra commit later; it's just for testing.

@dhardy dhardy mentioned this issue Feb 21, 2019
Closed
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@erickt @dhardy @gnzlbg