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Groups > comp.lang.c > #108231
| From | David Brown <david.brown@hesbynett.no> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: How to fix warning: [-Wdate-time] |
| Date | 2017-04-17 20:00 +0200 |
| Organization | A noiseless patient Spider |
| Message-ID | <od2vlm$n77$1@dont-email.me> (permalink) |
| References | (3 earlier) <ln4lxrugws.fsf@kst-u.example.com> <ocr1he$744$2@dont-email.me> <ocr42a$i2o$1@dont-email.me> <od2j51$b8r$1@dont-email.me> <a4acb94e-d478-f453-fc6d-0b6f8683cb69@verizon.net> |
On 17/04/17 16:52, James R. Kuyper wrote: > On 04/17/2017 10:26 AM, David Brown wrote: >> On 14/04/17 20:26, James Kuyper wrote: >>> On 04/14/2017 01:42 PM, Ken Brody wrote: > ... >>>> Why force an entire project to be compiled with "-Wno-date-time" >>>> for one >>>> macro? >>> >>> Because the entire project is one for which the motivations for that >>> warning don't apply? It is really a rather obscure issue to be warning >>> about. >>> >> >> IMHO, it is a very good thing to be warning about. If your program >> contains the macros __DATA__ or __TIME__, then your builds are not >> reproducible. I cannot think of any other way to make a build >> non-deterministic, at least on compilers I have used. >> >> That means that as long as you avoid these macros, you can use the >> generated binary file as a way to check that you have exactly the same >> build as on a previous occasion. > > That's not a particularly useful thing to test with most of the software > I work on. As a general rule, if I'm compiling the code, something has > changed: the source code, one of the libraries it's connected to, the > compiler itself, or the operating system. The normal expectation is that > the generated binary file is NOT the same as any previously created. > In fact, in the past, we've used a version control system which included > a specialized variant of "make" which automatically checked whether all > files opened during a previous build of an object file (including all > #include files (recursively) and the compiler itself) still have the > same version they had during that build, and that all environment > variables have the same values they had during the previous build. If > so, it would restore a copy of the object file created by that previous > build, rather than rebuilding it. The object files themselves had > versions, and the same logic was used when linking them together in an > executable. We're not using that system anymore, but not because of that > feature - we found it rather convenient > > One of the first things several of my programs do when executed is put a > message in the status log containing the version number of the file that > contains the code which caused that message to be printed, along with > the current values of __DATE__ and __TIME__. I've found that information > to be fairly useful; more useful than knowing whether the object files > were identical to those created by a previous build. The requirements for this sort of thing vary greatly - for some kinds of development work, __DATE__ and __TIME__ are /exactly/ what you need. For others, they are exactly what you /don't/ need. So it is good for a compiler to have such a warning - and good that the warning is entirely optional!
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How to fix warning: [-Wdate-time] MehdiAmini <atorrses@gmail.com> - 2017-04-13 14:44 +0430
Re: How to fix warning: [-Wdate-time] Barry Schwarz <schwarzb@dqel.com> - 2017-04-13 05:28 -0700
Re: How to fix warning: [-Wdate-time] MehdiAmini <atorrses@gmail.com> - 2017-04-14 12:55 +0430
Re: How to fix warning: [-Wdate-time] Keith Thompson <kst-u@mib.org> - 2017-04-14 08:50 -0700
Re: How to fix warning: [-Wdate-time] Ken Brody <kenbrody@spamcop.net> - 2017-04-14 13:42 -0400
Re: How to fix warning: [-Wdate-time] James Kuyper <jameskuyper@verizon.net> - 2017-04-14 14:26 -0400
Re: How to fix warning: [-Wdate-time] David Brown <david.brown@hesbynett.no> - 2017-04-17 16:26 +0200
Re: How to fix warning: [-Wdate-time] "James R. Kuyper" <jameskuyper@verizon.net> - 2017-04-17 10:52 -0400
Re: How to fix warning: [-Wdate-time] David Brown <david.brown@hesbynett.no> - 2017-04-17 20:00 +0200
Re: How to fix warning: [-Wdate-time] Keith Thompson <kst-u@mib.org> - 2017-04-17 08:08 -0700
Re: How to fix warning: [-Wdate-time] David Brown <david.brown@hesbynett.no> - 2017-04-17 20:04 +0200
Re: How to fix warning: [-Wdate-time] Mehdi Amini <atorrses@gmail.com> - 2017-04-15 07:50 +0430
Re: How to fix warning: [-Wdate-time] Keith Thompson <kst-u@mib.org> - 2017-04-15 15:05 -0700
Re: How to fix warning: [-Wdate-time] Ken Brody <kenbrody@spamcop.net> - 2017-04-17 11:42 -0400
Re: How to fix warning: [-Wdate-time] supercat@casperkitty.com - 2017-04-17 08:55 -0700
Re: How to fix warning: [-Wdate-time] "James R. Kuyper" <jameskuyper@verizon.net> - 2017-04-17 11:57 -0400
Re: How to fix warning: [-Wdate-time] gazelle@shell.xmission.com (Kenny McCormack) - 2017-04-13 13:09 +0000
Re: How to fix warning: [-Wdate-time] jadill33@gmail.com - 2017-04-13 06:27 -0700
Re: How to fix warning: [-Wdate-time] supercat@casperkitty.com - 2017-04-15 08:56 -0700
Re: How to fix warning: [-Wdate-time] Keith Thompson <kst-u@mib.org> - 2017-04-15 15:01 -0700
Re: How to fix warning: [-Wdate-time] supercat@casperkitty.com - 2017-04-16 11:44 -0700
Re: How to fix warning: [-Wdate-time] Keith Thompson <kst-u@mib.org> - 2017-04-16 13:45 -0700
Re: How to fix warning: [-Wdate-time] Ken Brody <kenbrody@spamcop.net> - 2017-04-17 12:14 -0400
Re: How to fix warning: [-Wdate-time] Ken Brody <kenbrody@spamcop.net> - 2017-04-17 12:06 -0400
Re: How to fix warning: [-Wdate-time] Keith Thompson <kst-u@mib.org> - 2017-04-17 09:25 -0700
Re: How to fix warning: [-Wdate-time] "James R. Kuyper" <jameskuyper@verizon.net> - 2017-04-17 12:45 -0400
Re: How to fix warning: [-Wdate-time] Keith Thompson <kst-u@mib.org> - 2017-04-17 12:02 -0700
Re: How to fix warning: [-Wdate-time] "James R. Kuyper" <jameskuyper@verizon.net> - 2017-04-17 15:23 -0400
Re: How to fix warning: [-Wdate-time] Lowell Gilbert <lgusenet@be-well.ilk.org> - 2017-04-18 13:27 -0400
Re: How to fix warning: [-Wdate-time] Ken Brody <kenbrody@spamcop.net> - 2017-04-18 14:23 -0400
Re: How to fix warning: [-Wdate-time] Keith Thompson <kst-u@mib.org> - 2017-04-18 12:10 -0700
Re: How to fix warning: [-Wdate-time] raltbos@xs4all.nl (Richard Bos) - 2017-04-22 21:20 +0000
Re: How to fix warning: [-Wdate-time] James Kuyper <jameskuyper@verizon.net> - 2017-04-22 22:45 -0400
Re: How to fix warning: [-Wdate-time] Tim Rentsch <txr@alumni.caltech.edu> - 2017-04-17 11:30 -0700
Re: How to fix warning: [-Wdate-time] Keith Thompson <kst-u@mib.org> - 2017-04-17 12:30 -0700
Re: How to fix warning: [-Wdate-time] raltbos@xs4all.nl (Richard Bos) - 2017-04-22 21:24 +0000
Re: How to fix warning: [-Wdate-time] Tim Rentsch <txr@alumni.caltech.edu> - 2017-04-27 13:33 -0700
Re: How to fix warning: [-Wdate-time] Tim Rentsch <txr@alumni.caltech.edu> - 2017-04-27 13:26 -0700
Re: How to fix warning: [-Wdate-time] gordonb.5zr1e@burditt.org (Gordon Burditt) - 2017-04-14 13:35 -0500
Re: How to fix warning: [-Wdate-time] supercat@casperkitty.com - 2017-04-14 12:17 -0700
Re: How to fix warning: [-Wdate-time] gordonb.k4gmo@burditt.org (Gordon Burditt) - 2017-04-16 00:04 -0500
Re: How to fix warning: [-Wdate-time] Noob <root@127.0.0.1> - 2017-04-16 11:04 +0200
Re: How to fix warning: [-Wdate-time] supercat@casperkitty.com - 2017-04-16 11:52 -0700
Re: How to fix warning: [-Wdate-time] raltbos@xs4all.nl (Richard Bos) - 2017-04-22 21:28 +0000
Re: How to fix warning: [-Wdate-time] Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-04-18 21:34 -0600
Re: How to fix warning: [-Wdate-time] Keith Thompson <kst-u@mib.org> - 2017-04-17 08:09 -0700
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