Add pthread_sigqueue to linux/other

[martinhath]

I'm not too sure about where to put this, as it seems to be a GNU extension, but other pthread functions that were also GNU extensions, like pthread_rwlockattr_setkind_np was in the same file, so I just put it directly above.

[rust-highfive]

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[alexcrichton]

Thanks! Looks like there's some style errors on CI though?

[martinhath]

Yeah, there's something off here.

cargo:warning=/checkout/target/x86_64-unknown-linux-gnu/debug/build/libc-test-c51dd8e7821c7fe7/out/main.c:20982:76: error: 'sigval' defined as wrong kind of tag
cargo:warning=             int (*__test_fn_pthread_sigqueue(void))(pthread_t, int, struct sigval) {
cargo:warning=                                                                            ^~~~~~
cargo:warning=/checkout/target/x86_64-unknown-linux-gnu/debug/build/libc-test-c51dd8e7821c7fe7/out/main.c:20982:76: error: 'struct sigval' declared inside parameter list will not be visible outside of this definition or declaration [-Werror]
cargo:warning=/checkout/target/x86_64-unknown-linux-gnu/debug/build/libc-test-c51dd8e7821c7fe7/out/main.c: In function '__test_fn_pthread_sigqueue':
cargo:warning=/checkout/target/x86_64-unknown-linux-gnu/debug/build/libc-test-c51dd8e7821c7fe7/out/main.c:20983:24: error: return from incompatible pointer type [-Werror=incompatible-pointer-types]
cargo:warning=                 return pthread_sigqueue;
cargo:warning=                        ^~~~~~~~~~~~~~~~
cargo:warning=cc1: all warnings being treated as errors
exit code: 1

It looks like it complaints about the sigval type, which is defined in src/unix/mod.rs:156:

pub struct sigval {
    // Actually a union of an int and a void*
    pub sival_ptr: *mut ::c_void
}

although its use seems fine in other contexts, like src/unix/notbsd/mod.rs:168

pub struct sigevent {
    pub sigev_value: ::sigval,
    pub sigev_signo: ::c_int,

According to the man pages I found online (and for sigevent), the types should be the same: union sigval (well, sigqueue uses const union sigval, but from the error message it looks like its the struct that's the problem?)

[alexcrichton]

I think that error is because in C the signature is different, maybe sigval is taken by a pointer?

[martinhath]

Both are supposed to be sigval, but in C the sigval is a

union sigval {
    int     sival_int;
    void   *sival_ptr;
};

The current sigval that we have is just the void * variant, as shown in my previous comment. It seems that enum arguments are a problem for libc in any case? rg "union" shows quite a few "Actually a union of ..."

[alexcrichton]

Looks like on CI the signature may still not match?

Especially with signals I've found that the documented standard and the actual headers tend to differ a bit...

[alexcrichton]

I'm gonna close this now due to inactivity, but it can of course be resubmitted!