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It's a C99 feature, and clang's the only compiler I know of that produces the diagnostic (and only in later versions) btw; I wrote this talk.

• gjulianm 14y ago
  I didn't know that. To answer my previous question, clang doesn't fire a warning when passing pointers of any size to the function foo. And by the way, nice talk, it's great learning these dark secrets of C.
  • adsr 14y ago
    But a pointer is not the same thing as an array, a pointer does not carry the size of the allocated space which an array does in the same scope.
  • rjek 14y ago
    The compiler can't know at compile time with a naked pointer like it can with an array. [static 1] is handy to say it must not explicitly be NULL, as if it were optional, however.
    • gjulianm 14y ago
      Yes, but I expected some kind of "You're passing a pointer as an array of size n. I can't check the size, but you should make sure you've checked it".
      • ori_b 14y ago
        I can't imagine that would be anything but noise. 99% of my function calls have pointers passed through, not arrays.
• tobiasu 14y ago
  Good, because I was missing a slide: = Bitfields = Not even once. ;)
  • rjek 14y ago
    Everybody knows about bitfields :)
    • JoshTriplett 14y ago
      Bitfields have some crazy fun dark corners, though. For instance, which values can this bitfield hold: int b:1; Signed two's-complement n-bit integers can hold values from 2^(n-1)-1 to -2^(n-1), so in theory it can hold 0 and -1, but many compilers get that one wrong. Always declare one-bit bitfields as unsigned. (The Sparse static analyzer will warn you about that one.)