Add support for alternative QNX Neutrino network stack `io-sock`

[flba-eb]

Description

QNX 7.1 supports two network stacks:

1. io-pkt, which is default
2. io-sock, which is optional and should be default in QNX 8.0

As one can see in the io-sock migration notes, this changes the libc API in a way similar to e.g. linux-gnu vs. linux-musl.

This change uses a new target which has a different value for target_env, so that e.g. libc can distinguish between both APIs. New target pull request for rustc: https://github.com/rust-lang/rust/pull/133631

CC: @jonathanpallant @japaric @gh-tr @AkhilTThomas

Sources

• Relevant tests in libc-test/semver have been updated ⚠️ QNX is unfortunately not ABI compatible between versions, hence semver checks are not possible.
• [x] No placeholder or unstable values like *LAST or *MAX are included (see #3131)
• [x] Tested locally (cd libc-test && cargo test --target mytarget); especially relevant for platforms that may not be checked in CI

[rustbot]

r? @JohnTitor

rustbot has assigned @JohnTitor. They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

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[bors]

:umbrella: The latest upstream changes (presumably #4198) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

:umbrella: The latest upstream changes (presumably #4202) made this pull request unmergeable. Please resolve the merge conflicts.

[flba-eb]

@tgross35 would it make sense to take over from @JohnTitor ? Asking because of 65d0ffbd90fe8d79a16f4cb006db8ce985d28793.

[tgross35]

Also, looks like the first two commits could be squashed

[flba-eb]

Also, looks like the first two commits could be squashed

Done. The test failures of freebsd tests seem to be unrelated.

[jonathanpallant]

Building libc_test also failed (I didn't expect it to run, because this host is not running QNX, but I expected it to build):

bash -c "source ~/qnx710/qnxsdp-env.sh && criticalup run cargo test --target=aarch64-unknown-nto-qnx710"
QNX_HOST=/Users/jonathan/qnx710/host/darwin/x86_64
QNX_TARGET=/Users/jonathan/qnx710/target/qnx7
MAKEFLAGS=-I/Users/jonathan/qnx710/target/qnx7/usr/include
   Compiling proc-macro2 v1.0.93
   Compiling unicode-ident v1.0.14
   Compiling libc v0.2.169
   Compiling serde v1.0.217
   Compiling memchr v2.7.4
   Compiling cfg-if v0.1.10
   Compiling serde_json v1.0.135
   Compiling semver v1.0.24
   Compiling unicode-xid v0.2.6
   Compiling itoa v1.0.14
   Compiling ryu v1.0.18
   Compiling shlex v1.3.0
   Compiling bitflags v1.3.2
   Compiling log v0.4.22
   Compiling regex-syntax v0.8.5
   Compiling cc v1.2.9
   Compiling libc v1.0.0-alpha.1 (/Users/jonathan/Documents/open-source/libc_testing/libc)
   Compiling unicode-width v0.2.0
   Compiling anstyle v1.0.10
   Compiling aho-corasick v1.1.3
   Compiling rustc_version v0.4.1
   Compiling annotate-snippets v0.11.5
   Compiling glob v0.3.2
   Compiling quote v1.0.38
   Compiling dirs-sys v0.3.7
   Compiling syn v2.0.96
   Compiling dirs v2.0.2
   Compiling term v0.6.1
warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:128:15
    |
128 |     #[cfg(not(target_env = "nto71_iosock"))]
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:137:11
    |
137 |     #[cfg(target_env = "nto71_iosock")]
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:248:15
    |
248 |     #[cfg(not(target_env = "nto71_iosock"))]
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:279:15
    |
279 |     #[cfg(not(target_env = "nto71_iosock"))]
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:285:11
    |
285 |     #[cfg(target_env = "nto71_iosock")]
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:614:15
    |
614 |     #[cfg(not(target_env = "nto71_iosock"))]
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:622:11
    |
622 |     #[cfg(target_env = "nto71_iosock")]
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:653:15
    |
653 |     #[cfg(not(target_env = "nto71_iosock"))]
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:754:15
    |
754 |     #[cfg(not(target_env = "nto71_iosock"))]
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:766:11
    |
766 |     #[cfg(target_env = "nto71_iosock")]
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
    --> src/unix/nto/mod.rs:1277:18
     |
1277 |     if #[cfg(not(target_env = "nto71_iosock"))] {
     |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
     = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
     = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
    --> src/unix/nto/mod.rs:2938:18
     |
2938 |     if #[cfg(not(target_env = "nto71_iosock"))] {
     |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
     = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
     = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: `libc` (lib) generated 12 warnings
   Compiling regex-automata v0.4.9
   Compiling serde_derive v1.0.217
   Compiling regex v1.11.1
   Compiling garando_pos v0.1.0
   Compiling garando_errors v0.1.0
   Compiling garando_syntax v0.1.1
   Compiling ctest2 v0.4.9
   Compiling libc-test v0.1.0 (/Users/jonathan/Documents/open-source/libc_testing/libc/libc-test)
warning: [email protected]: warning: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: archive library: /Users/jonathan/Documents/open-source/libc_testing/libc/target/aarch64-unknown-nto-qnx710/debug/build/libc-test-93769fdecc84d0de/out/libcmsg.a the table of contents is empty (no object file members in the library define global symbols)
warning: [email protected]: warning: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: archive library: /Users/jonathan/Documents/open-source/libc_testing/libc/target/aarch64-unknown-nto-qnx710/debug/build/libc-test-93769fdecc84d0de/out/libmain.a the table of contents is empty (no object file members in the library define global symbols)
error[E0432]: unresolved imports `libc::B230400`, `libc::DT_BLK`, `libc::DT_CHR`, `libc::DT_DIR`, `libc::DT_FIFO`, `libc::DT_LNK`, `libc::DT_REG`, `libc::DT_SOCK`, `libc::GRPQUOTA`, `libc::PRIO_MAX`, `libc::PRIO_MIN`, `libc::SA_ONSTACK`, `libc::SA_RESTART`, `libc::USRQUOTA`, `libc::cfmakeraw`, `libc::cfsetspeed`
   --> /Users/jonathan/Documents/open-source/libc_testing/libc/target/aarch64-unknown-nto-qnx710/debug/build/libc-test-93769fdecc84d0de/out/semver.rs:16:5
    |
16  |     B230400,
    |     ^^^^^^^
    |     |
    |     no `B230400` in the root
    |     help: a similar name exists in the module: `B2400`
...
38  |     DT_BLK,
    |     ^^^^^^ no `DT_BLK` in the root
39  |     DT_CHR,
    |     ^^^^^^ no `DT_CHR` in the root
40  |     DT_DIR,
    |     ^^^^^^ no `DT_DIR` in the root
41  |     DT_FIFO,
    |     ^^^^^^^ no `DT_FIFO` in the root
42  |     DT_LNK,
    |     ^^^^^^ no `DT_LNK` in the root
43  |     DT_REG,
    |     ^^^^^^ no `DT_REG` in the root
44  |     DT_SOCK,
    |     ^^^^^^^ no `DT_SOCK` in the root
...
152 |     GRPQUOTA,
    |     ^^^^^^^^ no `GRPQUOTA` in the root
...
276 |     PRIO_MAX,
    |     ^^^^^^^^ no `PRIO_MAX` in the root
277 |     PRIO_MIN,
    |     ^^^^^^^^
...
299 |     SA_ONSTACK,
    |     ^^^^^^^^^^
300 |     SA_RESETHAND,
301 |     SA_RESTART,
    |     ^^^^^^^^^^
...
404 |     USRQUOTA,
    |     ^^^^^^^^
...
485 |     cfmakeraw,
    |     ^^^^^^^^^
...
488 |     cfsetspeed,
    |     ^^^^^^^^^^

For more information about this error, try `rustc --explain E0432`.

[jonathanpallant]

I'm seeing build warnings that should probably be addressed?

manifest-version = 1

[products.ferrocene]
release = "stable-25.02.0"
packages = [
    "rustc-${rustc-host}",
    "rust-std-${rustc-host}",
    "cargo-${rustc-host}",
    "llvm-tools-${rustc-host}",
    "rust-src",
    "rust-std-aarch64-unknown-nto-qnx710",
]

$ bash -c "source ~/qnx710/qnxsdp-env.sh && criticalup run cargo build --target=aarch64-unknown-nto-qnx710"
QNX_HOST=/Users/jonathan/qnx710/host/darwin/x86_64
QNX_TARGET=/Users/jonathan/qnx710/target/qnx7
MAKEFLAGS=-I/Users/jonathan/qnx710/target/qnx7/usr/include
warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:128:15
    |
128 |     #[cfg(not(target_env = "nto71_iosock"))]
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:137:11
    |
137 |     #[cfg(target_env = "nto71_iosock")]
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:248:15
    |
248 |     #[cfg(not(target_env = "nto71_iosock"))]
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:279:15
    |
279 |     #[cfg(not(target_env = "nto71_iosock"))]
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:285:11
    |
285 |     #[cfg(target_env = "nto71_iosock")]
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:614:15
    |
614 |     #[cfg(not(target_env = "nto71_iosock"))]
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:622:11
    |
622 |     #[cfg(target_env = "nto71_iosock")]
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:653:15
    |
653 |     #[cfg(not(target_env = "nto71_iosock"))]
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:754:15
    |
754 |     #[cfg(not(target_env = "nto71_iosock"))]
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
   --> src/unix/nto/mod.rs:766:11
    |
766 |     #[cfg(target_env = "nto71_iosock")]
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
    --> src/unix/nto/mod.rs:1277:18
     |
1277 |     if #[cfg(not(target_env = "nto71_iosock"))] {
     |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
     = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
     = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: unexpected `cfg` condition value: `nto71_iosock`
    --> src/unix/nto/mod.rs:2938:18
     |
2938 |     if #[cfg(not(target_env = "nto71_iosock"))] {
     |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
     = note: expected values for `target_env` are: ``, `aix`, `gnu`, `illumos`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `p1`, `p2`, `psx`, `relibc`, `sgx`, `uclibc`, and `wasi`
     = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration

warning: `libc` (lib) generated 12 warnings
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.01s

[flba-eb]

Most of the warnings are coming from a compiler which does not understand or know the selected target. The unresolved imports should also be caused by the compiler not understanding the target. Can you try with a nightly? On the other hand, you've already verified some of the new values. Maybe it is sufficient to review that the structure of the change is okay; I don't see too much value in (manually) verifying all values.

[jonathanpallant]

Oh, I see! Is this going to raise the MSRV on the libc crate, even for people who aren't using the new target? I was still building it with the old non-io-sock target.

Building with nightly shows that the warnings have gone.

[tgross35]

Oh, I see! Is this going to raise the MSRV on the libc crate, even for people who aren't using the new target? I was still building it with the old non-io-sock target.

It's not actually a problem since the warning will be quiet if you're not building the crate directly, but it would probably be good to add the environment to https://github.com/rust-lang/libc/blob/b550c6b59d2a7f031a965e61b6d1326d9c74a9f3/build.rs#L32 for anyone working on libc+qnx.

Usually CI denies warnings and tests with the MSRV, but the relevant target_env uses are all gated within the nto module.

[tgross35]

@rustbot author

Could you add the check config mentioned above? After that I'm happy to merge.

This also needs a rebase.

[flba-eb]

@rustbot ready

[flba-eb]

@tgross35 anything left for me to do?