Careful with that example. The parentheses here don't just remove the warning. T... | Hacker News

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loup-vaillant on Aug 20, 2014 | parent | context | favorite | on: fork() can fail

Careful with that example. The parentheses here don't just remove the warning. They remove a bug. This code:

  if (buf = malloc(buflen) == NULL)
      goto outofmemory;

is actually equivalent to that code:

  if (buf = (malloc(buflen) == NULL))
      goto outofmemory;

So, malloc gives you a pointer, which is compared to the null pointer, giving you either 0 or 1. And that is assigned to buf. Hopefully your compiler will warn you about the type error that spawns from such dark magic.

cperciva on Aug 20, 2014 | [–]

Oops, quite right. I was originally thinking of

    if ((rc = pthread_mutex_lock(mtx)))
        err("mutex_lock failed: %s", strerror(rc));

but decided to switch to a better-known function at the last minute and completely lost the point.

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