Thomas Wolff via Cygwin writes: > cygwin has changed it already by defining wchar_t as 16-bit. My fix > only reverts this.
Nope. That's not a Cygwin thing and wchar_t can be anything, even less than 16bit, as far as the standards are concerned. Yes, that's messy, but it is what it is. >> The fix for your bug is easy enough > It's just not a fix because it narrows the parameter to 16 bits and > thus breaks current wcwidth functionality. It doesn't break anything that wasn't already broken before. There can be no correct Cygwin program that can use an argument to wcwidth that has more than 16 bits (and your own example doesn't use any of these anyway). The public interface always was wchar_t (nee unsigned short on Cygwin) and the extension to the win_t in the implementation function in newlib libc just wasn't working as you (still?) seem to think it does when you mismatch the types. The type extension of function arguments (via register sharing) on x86_64 is undefined, the resulting upper 16 bits in this case (wchar_t --> wint_t) can be anything: zero extension, sign extension or even random bits. This is just not something that can work reliably. I don't know what aarch64 does on that front. In your example, you use an int as argument, which is used as a function argument declared as short unsigned (via wchar_t, so it gets truncated to 16 bit, at least logically) and then used an int again inside the actual implementation of that function. This is wrong as the prototype and the implementation don't match, but the ABI only guarantees that the lower 16 bit of the original argument transfer in that case. Even if zero extension was used you'd lose any upper bits in the original argument anyway (which you say works for your example and I'd argue that there can't be any upper bits anyway on Cygwin, see aboive), which is exactly what will _definitely_ happen if the libc implementation stub is reverted to the correct signature. Regards, Achim. -- +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ SD adaptation for Waldorf rackAttack V1.04R1: http://Synth.Stromeko.net/Downloads.html#WaldorfSDada -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
