Including <cerrno> instead of <errno.h>, does it upset POSIX?

[Ahmad Samir]

Hello :)

A week or so ago I created an MR to include <cerrno> instead of <errno.h> in KIO[1].

 From /usr/include/c++/10/cerrno:
/** @file cerrno
  *  This is a Standard C++ Library file.  You should @c \#include this file
  *  in your programs, rather than any of the @a *.h implementation files.
  *
  *  This is the C++ version of the Standard C Library header @c errno.h,
  *  and its contents are (mostly) the same as that header, but are all
  *  contained in the namespace @c std (except for names which are defined
  *  as macros in C).
  */


And then I made similar commits to a lot of the other Frameworks (not all, since the build failed 
for some of them, so I left them alone).

Harald Sitter asked me to raise the point here, basically he's wondering whether this change might 
cause issues, not being 100% POSIX compliant...etc; I'll quote him because he explained it much 
better than I would:

<sitter> ahmadsamir: 
https://invent.kde.org/frameworks/kcrash/-/commit/7a20755723dc1527edb7ed5c3fdcccdbcf7fa768 was this 
ever discussed anywhere? cause there are others like this and my thinking up until now was that 
using the C .h is more appropriate since we use them for POSIX APIs and from that POV the POSIX 
specified header is errno.h

[...]

<sitter> might be worth raising for discussion on the mailing list. with c++>=14 there's a whole 
mountain of "deprecated" headers OTOH I also recall reading that the c++ standard doesn't guarantee 
compatibility
<sitter> which may or may not be a concern when we use stuff specifically with the expectation that 
they will behave as documented from a POSIX or linux POV (such as signal safety in kcrash)


[1] https://invent.kde.org/frameworks/kio/-/merge_requests/397
-- 
Ahmad Samir