Re: Fixing the warning about warning(""); was: Re: [PATCH] difftool.c: mark a file-local symbol with static

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Hannes,

On Thu, 26 Jan 2017, Johannes Sixt wrote:

> Am 25.01.2017 um 23:01 schrieb Jeff King:
> > +#pragma GCC diagnostic ignored "-Wformat-zero-length"
> 
> Last time I used #pragma GCC in a cross-platform project, it triggered
> an "unknown pragma" warning for MSVC.

It is starting to become a little funny how many ways we can discuss the
resolution of the GCC compiler warning.

And it starts to show: we try to solve the thing in so many ways, just to
avoid the obviously most-trivial patch to change warning(""); to
warning("%s", "") (the change to warning(" "); would change behavior, but
I would be fine with that, too).

I am not really interested in any of these complicated workarounds. If you
gentle people decide they are better in Git's source code, go ahead. I do
not have to like what you are doing, I just have to work with it.

> (It was the C++ compiler, I don't know if the C compiler would also
> warn.) It would have to be spelled like this:
> 
> #pragma warning(disable: 4068)   /* MSVC: unknown pragma */
> #pragma GCC diagnostic ignored "-Wformat-zero-length"
> 
> Dscho mentioned that he's compiling with MSVC. It would do him a favor.

I am compiling with MSVC, and the idea is to tap into that large number of
Windows developers who Git traditionally has had a really bad time
attracting. From that perspective, I would say it would not only do me a
favor, but anybody who builds Git for Windows using Visual Studio.

But we also have to consider whether it would do anybody a "dis-favor".
#pragma statements are by definition highly dependent on the compiler. I
have no idea whether there are developers out there building Git with
C compilers other than GCC, clang or MSVC (as I did back in the days on
IRIX and HP/UX), but there is quite the potential for problems here [*1*].

To keep Git's source code truly portable, the #pragma would have to be
guarded by a GCC-specific #ifdef ... #endif.

Ciao,
Dscho

Footnote *1*: This is just another instance where a discussion on the Git
mailing list reminds me of
http://thedailywtf.com/articles/The_Complicator_0x27_s_Gloves, as it tries
to avoid an obvious solution by trying to come up with a different
solution that in turn requires additional solutions to additional problems
caused by the alternative solution.