Re: Bad interaction between signal constants and -Wsign-conversion

[Vincent Lefevre <vincent@vinc17.net>]

On 2023-03-30 16:09:12 +0200, Alejandro Colomar wrote:
> On 3/30/23 15:59, Vincent Lefevre wrote:
> > But concerning struct sigaction in particular, shouldn't this be fixed
> > in POSIX?
> 
> IMHO, POSIX, and in general, standards, should follow implementations
> rather than lead them.  I think changes should start as vendor
> extensions.

However, there could be a discussion concerning POSIX at the same time.

> For example, timespec::tv_nsec was mandated to be long by POSIX and
> C11, but glibc used 'long long' in some cases, because it was
> necessary.  I would say using 'unsigned int' here would be a nice GNU
> extension, and if it proves its value, POSIX could later pick it.
> 
> However, as Zack said, I'm not sure how we could check if any programs
> out there are using this member unreasonably.

But on the opposite, it is possible that some programs assume that
flags are positive and these programs have not been tested with a
negative flag. So they could already be buggy, and an unsigned int
could fix them.

BTW, some systems seem to have an unsigned sa_flags:

  https://github.com/github/git-msysgit/blob/master/compat/mingw.h
  https://www.google.com/search?q=%22unsigned+long+sa_flags%22
  https://www.google.com/search?q=%22unsigned+int+sa_flags%22

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)