Re: [RFC PATCH v3 00/15] Modernize the build system

From: Ramsay Jones <ramsay@ramsayjones.plus.com>
Date: Oct 24, 2024, 01:43 UTC
Message-ID: <b1ab6c1a-54ce-4adb-8977-ef376fdb48f1@ramsayjones.plus.com>
In-Reply-To: <6883a8d4-7e2e-4988-b57f-89b7c0aacadc@gentoo.org>

On 23/10/2024 16:58, Eli Schwartz wrote:

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> On 10/23/24 10:38 AM, Ramsay Jones wrote:
>> Hmm, I could have sworn that this caused a complete rebuild for me
>> (even when having just built), hence the '--no-rebuild --print-errorlogs'
>> parameters to meson test. (Oh, maybe that was just 'meson test' - so
>> how do you run *all* tests with meson - rather than 'ninja test').
> 
> 
> "meson test" without --no-rebuild will first run "ninja" to verify that
> everything has been built, and build it if it hasn't been. When passing
> specific test names, it will filter for dependencies of that specific
> testcase, and only ensure *those* are up to date. Assuming those
> dependencies are accurate, of course. :D

Heh, yes, I just tried it tonight, and it did just as you describe:

  $ meson test
  ninja: Entering directory `/home/ramsay/new-git/build'
  ninja: no work to do.
  $

> What do you mean by "complete rebuild"? Do you mean all binaries that
> were already built and up to date get marked stale and recreated?

My bad, I was a little loose in my language. Whatever it was that I typed (and I obviously can't remember what it was!), resulted in meson going through the configuration step again followed by compilation/linking of all binaries (or at least, that's what it looked like).

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>> BTW, I have been doing:
>>
>>   $ meson setup .. -Dprefix=$HOME
>>
>> so that it matches the default prefix from the Makefile (not that I
>> have attempted to actually install yet!;) ). Can the default be set
>> in the meson.build file (with command-line override, of course)?
> 
> 
> project('git', 'c',
>   meson_version: '>=1.3.0',
>   # MSVC does not support GNU99, and C99 does not define __STDC_VERSION__
>   # on MSVC. So we instead fall back to C11 there.
>   default_options: ['c_std=gnu99,c11'],

Ah yes, this seems to work:

  $ git diff
  diff --git a/meson.build b/meson.build
  index 7c7a59d7fb..23b6f0baa2 100644
  --- a/meson.build
  +++ b/meson.build
  @@ -2,7 +2,7 @@ project('git', 'c',
     meson_version: '>=1.3.0',
     # MSVC does not support GNU99, and C99 does not define __STDC_VERSION__
     # on MSVC. So we instead fall back to C11 there.
  -  default_options: ['c_std=gnu99,c11'],
  +  default_options: ['c_std=gnu99,c11', 'prefix=$HOME'],
     version: 'v2.47.GIT',
   )
 
  $ 
  $ meson setup .. --reconfigure
  ...
    User defined options
      prefix: /home/ramsay

  Found ninja-1.12.0 at /usr/bin/ninja
  Cleaning... 0 files.
  $

Using the command-line to override also works:

  $ meson setup .. --reconfigure -Dprefix=/usr/local
  ...

    User defined options
      prefix: /usr/local

  Found ninja-1.12.0 at /usr/bin/ninja
  Cleaning... 0 files.
  $

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> You can pass any command-line options in as default_options, including
> prefix. Defaulting to $HOME is somewhat unconventional regardless of
> whether it's done in a Makefile or a configure.ac or a meson.build or a
> CMakeLists.txt, but given the Makefile does indeed do that I suppose
> it's not incredibly bizarre to do it in meson.build as well. :)

I don't have any strong feelings either way, it's just that people are used to doing a 'make install' and having the git build installed in their home directory (including me). But it is not a huge effort to add the '-Dprefix=$HOME', it simply needs to be documented.

I think I need to go away and RTFM at this point and not annoy you (and others) with such noob questions! :)

[For me ATM, meson works fine on Linux, but it simply doesn't work at all on cygwin as far as the tests are concerned (and I haven't tried installing yet). Patrick is not seeing any problems, so I would like to understand why we have such different results.]

Thanks!

ATB, Ramsay Jones