__error() not provided for x86_64-unknown-dragonfly

[tuxillo]

• Target: x86_64-unknown-dragonfly (not in the CI)
• Instructions to reproduce: just try to build in this platform

After commit 3fa021d, libc won't provide __error() for DragonFly. We've spotted this by trying to build rust-1.39, which includes a newer libc crate (0.2.62) that contains this change.

The error shows up when the build tries to make use of libc::__error():

error[E0432]: unresolved import `libc::__error`
  --> /usr/obj/dports/lang/rust.139/rustc-1.39.0-src/vendor/getrandom/src/util_libc.rs:22:13
   |
22 |         use libc::__error as errno_location;
   |             ^^^^^^-------^^^^^^^^^^^^^^^^^^
   |             |     |
   |             |     help: a similar name exists in the module: `ferror`
   |             no `__error` in the root

error: aborting due to previous error

For more information about this error, try `rustc --explain E0432`.
error: Could not compile `getrandom`.
warning: build failed, waiting for other jobs to finish...
error: build failed
command did not execute successfully: "/usr/obj/dports/lang/rust.139/rustc-1.39.0-src/build/x86_64-unknown-dragonfly/stage0/bin/cargo" "build" "-Zconfig-profile" "--target" "x86_64-unknown-dragonfly" "-Zbinary-de
p-depinfo" "-j" "24" "--release" "--frozen" "--features" "" "--manifest-path" "/usr/obj/dports/lang/rust.139/rustc-1.39.0-src/src/rustc/Cargo.toml" "--message-format" "json-render-diagnostics"
expected success, got: exit code: 101
Traceback (most recent call last):
  File "/usr/obj/dports/lang/rust.139/rustc-1.39.0-src/x.py", line 11, in <module>
    bootstrap.main()
  File "/usr/obj/dports/lang/rust.139/rustc-1.39.0-src/src/bootstrap/bootstrap.py", line 913, in main
    bootstrap(help_triggered)
  File "/usr/obj/dports/lang/rust.139/rustc-1.39.0-src/src/bootstrap/bootstrap.py", line 899, in bootstrap
    run(args, env=env, verbose=build.verbose)
  File "/usr/obj/dports/lang/rust.139/rustc-1.39.0-src/src/bootstrap/bootstrap.py", line 141, in run
    raise RuntimeError(err)
RuntimeError: failed to run: /usr/obj/dports/lang/rust.139/rustc-1.39.0-src/build/bootstrap/debug/bootstrap build --verbose --config ./config.toml --jobs 24
*** Error code 1

Stop.
make[1]: stopped in /usr/dports/lang/rust.139
*** Error code 1

Stop.

Let me know if you need additional information and I'll provide it.

[gnzlbg]

AFAICT the __error function is still available on DragonflyBSD. It was previously only provided if cfg!(libc_thread_local) is true, and that remains to be the case. cc @josephlr

[tuxillo]

As far as I can tell, even removing the conditional so that the feature is always enabled is not enough for this to build.

I changed:

#![cfg_attr(libc_thread_local, feature(thread_local))]

to

#![feature(thread_local)]

Maybe I'm missing something?

[josephlr]

Sorry about missing this, it slipped by me over the holidays. #1432 added __error for DragonflyBSD, but only when the libc crate is a dependency of libstd. The reasoning is here: #1432 (comment) Essentially, getting DragonflyBSD errno to work requires nightly, but all the crates that would use this feature don't want to require nightly.

The reason you're hitting this issue is my fault however, see rust-random/getrandom#124. This was fixed in rust-random/getrandom#129 , which was released with getrandom 0.1.14.

Regardless, I think this issue can be closed.

[tuxillo]

Thanks for the info. Please hold this off a bit, we're about to release 5.8 which has __errno_location, and in that case we can fall into the linux case, see this: https://github.com/DragonFlyBSD/DeltaPorts/blob/master/ports/games/veloren/dragonfly/patch-util_libc.rs

[tuxillo]

We have now released 5.8 which contains __errno_location

[tuxillo]

See this commit, its now provided from libc in both stable and head releases:
https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/60d311380ff2bf02a87700a0f3e6eb53e6034920

commit 60d311380ff2bf02a87700a0f3e6eb53e6034920
Author: zrj <rimvydas.jasinskas@gmail.com>
Date:   Sat Oct 5 13:04:12 2019 +0300

    libc: Add __errno_location() for language binding benefits.
    
     Some languages have restrictions when it comes to C style TLS handling
     (thread local might be feature-gated) or simply it is inconvenient to
     add various OS specific binding wrappers just to access C errno values.
    
     The __errno_location() symbol provides externally callable version of
     __error() inline function.
    
     While there, add __WANT_NO_INLINED___ERROR guard for few python parsers
     in DPorts that are unable to parse inlined __error() code yet.

It coud be exported in src/unix/bsd/freebsdlike/dragonfly/mod.rs via extern C, which is what we do for fixing Rust packages.

[JohnTitor]

Fixed by #1875.