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Comment by rjek | Hacker News Reader

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.

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.

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.

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".

I can't imagine that would be anything but noise. 99% of my function calls have pointers passed through, not arrays.

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.

Good, because I was missing a slide:

= Bitfields =

Not even once.

;)

Everybody knows about bitfields :)

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.)

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