Dynamically loading libjulia with `SIGCHLD` ignored causes error `waitpid: No child processes`

[topolarity]

#include <dlfcn.h>
#include <stdio.h>
#include <signal.h>

int main(int argc, char *argv[])
{
    signal(SIGCHLD, SIG_IGN);
    void *handle = dlopen(LIBJULIA_PATH, RTLD_LAZY);
    return 0;
}

$ gcc -fPIC testjulia.c -DLIBJULIA_PATH="`pwd`/usr/lib/libjulia.so"
$ ./a.out
Error during libstdcxxprobe in parent process:
waitpid: No child processes

[vtjnash]

Ignoring SIGCHLD makes it invalid to spawn child processes. This is a unix feature and not something julia can change.

[topolarity]

Ignoring SIGCHLD makes it invalid to spawn child processes. This is a unix feature and not something julia can change.

Julia should support running basic programs without needing to spawn child processes then.

[topolarity]

Or notice that SIGCHLD is ignored and back off from probing libstdc++ incorrectly

[vtjnash]

Or just don't block SIGCHLD? There are a lot of ways to set up an invalid configuration which we will not support.

[topolarity]

Or just don't block SIGCHLD? There are a lot of ways to set up an invalid configuration which we will not support.

We at least need a better error message IMO, since this is a report from a real situation in the wild.

We're trying to provide a good experience for using Julia-compiled versions of "simple" libraries whose C equivalents do not have so many of these "poorly composing" constraints around signals, thread lifetimes, etc. and trying to minimize that surface area (or else document/guard where it cannot be shrunk) is important, I think .