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Re: How can Autoconf help with the transition to stricter compilation de

From: Paul Eggert
Subject: Re: How can Autoconf help with the transition to stricter compilation defaults?
Date: Fri, 11 Nov 2022 01:02:20 -0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2

On 2022-11-10 19:33, Zack Weinberg wrote:

It would be relatively easy for me to take a couple hours this weekend and put 
out a 2.72 release with everything that's already in trunk and nothing else.  
Anyone have reasons I _shouldn't_ do that?

I don't have anything other than some doc updates, which I just now installed (see attached).

Note that in autoconf git, we've also got
which is going to affect time_t efforts too

I have not been following the y2038 work closely.  Is it going to affect things 
in a good way or a bad way??


This matters only on 32-bit glibc platforms running atop Linux (and maybe Hurd; I haven't checked). On these platforms, time_t defaults to 32 bits which means programs stop working in the year 2038. But you can change time_t to be 64-bits if you compile with -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64. On other platforms, you don't need to worry about this stuff.

The good news is that if an app uses AC_SYS_LARGEFILE (which most sane apps do), or uses the new macro AC_YEAR2038, it will keep working after the year 2038 on these platforms.

The bad news is that if a library uses AC_SYS_LARGEFILE and/or AC_YEAR2038, and the library code is built without using configure's --disable-largefile option and is linked with a program that doesn't use AC_SYS_LARGEFILE or AC_YEAR2038 or equivalent, and if the library's ABI depends on time_t width, the program might not work.

This is the same issue that AC_SYS_LARGEFILE has had with 32-bit off_t for years (as well as for a few more obscure times like ino_t); what's new is that the problem now occurs with time_t too.

Attachment: 0001-Modernize-and-regularize-doc-for-C89-etc.patch
Description: Text Data

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