Re: Minor portability issues + fixes

From: Jeff King <peff@peff.net>
Date: May 19, 2020, 02:49 UTC
Message-ID: <20200519024945.GB70483@coredump.intra.peff.net>
In-Reply-To: <7422404e-7fc8-4961-aae4-3f0adb71bb3a@www.fastmail.com>

On Mon, May 18, 2020 at 09:15:58PM -0400, Daniel Richard G. wrote:

Show 13 quoted lines

> I am building Git 2.26.2 on AIX. A few compilation errors arose, but
> they are resolvable with a few minor changes that will improve overall
> portability.
> 
> There were a few errors of this form:
> 
>     sha1-file.c: In function 'mmap_limit_check':
>     sha1-file.c:940:12: error: 'SIZE_MAX' undeclared (first use in this function)
>     sha1-file.c:940:12: note: each undeclared identifier is reported only once for each function it appears in
> 
> SIZE_MAX is defined in stdint.h, and adding that #include fixes this. It
> is likely that this header is being pulled in on other platforms due to
> transitive dependencies, but that does not occur on AIX.

All system defines in Git should be pulled in via git-compat-util.h. That does include stdint.h, but only if NO_INTTYPES_H is defined (otherwise we prefer inttypes.h). And POSIX (2004) says:

  The <inttypes.h> header shall include the <stdint.h> header.

But perhaps that is not so on AIX (it wouldn't be the first time we've seen a platform that does not strictly follow POSIX).

Does building with:

  make NO_INTTYPES_H=YesPlease

work?

If so, then perhaps it should be added to the AIX defines in config.mak.uname.

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> The problem is, in this case, CC_LD_DYNPATH is set to an empty value---
> which is incorrect, in light of how it is used in the Makefile. Here is
> a typical example:
> 
>     ifdef ZLIB_PATH
>             BASIC_CFLAGS += -I$(ZLIB_PATH)/include
>             EXTLIBS += -L$(ZLIB_PATH)/$(lib) $(CC_LD_DYNPATH)$(ZLIB_PATH)/$(lib)
>     endif
>     EXTLIBS += -lz
> 
> Setting that variable to an empty value causes a bare directory to be
> passed to the linker, which of course then errors out. I would suggest
> setting it to "-L" instead.

That would just be redundant with the earlier argument. That might be the easiest way to turn it into a noop, but we can probably do better with $(if) or similar, which would allow somebody to build with:

  make CC_LD_DYNPATH=

even without using the autoconf script.

I do wonder, though, if configure.ac could be extended for AIX to support whatever syntax the system linker uses for setting the run-path. I understand that you don't care either way about this feature, but this might be a good opportunity to fix it.

-Peff