头文件编译时错误求助：sigset_t类型不兼容参数传递问题

The error you're hitting stems from a small but critical mistake in how you're using the sigismember() function. Let's break this down clearly:

The Root Cause #

The sigismember() function requires its first argument to be a pointer to a sigset_t (const sigset_t *), but in your code, you're passing the sigset_t variable old directly (by value) instead of its memory address. This mismatch is why the compiler complains about passing a sigset_t to a parameter expecting const sigset_t *.

Corrected Code #

Here's the fixed version of your function, with the problematic line adjusted:

static int pthread_setcancelstate(int state, int *oldstate) { 
    sigset_t new, old; 
    int ret; 

    sigemptyset(&new); 
    sigaddset(&new, SIG_CANCEL_SIGNAL); 

    ret = pthread_sigmask(
        state == PTHREAD_CANCEL_ENABLE ? SIG_BLOCK : SIG_UNBLOCK, 
        &new, 
        &old
    ); 

    if(oldstate != NULL) { 
        // Fixed: pass &old instead of old to sigismember()
        *oldstate = sigismember(&old, SIG_CANCEL_SIGNAL) == 0 ? 
            PTHREAD_CANCEL_DISABLE : 
            PTHREAD_CANCEL_ENABLE; 
    } 

    return ret; 
}

Why This Works #

• sigismember(const sigset_t *set, int signo) checks if a signal exists in the set pointed to by set. By passing &old, you're providing the pointer it needs to access the sigset_t variable you populated with pthread_sigmask().
• The rest of your code was already correct: you’re using &new and &old with pthread_sigmask() (which also expects pointers to sigset_t), so that part never caused the error.

内容的提问来源于stack exchange，提问作者Golu