[Scons-users] Using CheckFunc() and CheckLib() breaks dependencies and makes scons ignore file changes

[Bill Deegan]

Also see:
http://scons.org/doc/production/HTML/scons-user/ch23s09.html

with regards to ignoring configure checks when running scons -c

-Bill

On Tue, Feb 14, 2017 at 12:36 PM, Bill Deegan <bill at baddogconsulting.com>
wrote:

> There's the config.log which is where the output from the check* calls is
> recorded.
> (This is also the case with autoconfig whose functionality is being
> (incompletely in that not all autoconfig checks are implemented, but the
> output of the builds to config.log is correctly) mimicked)
>
> That is where you go to determine why your configure context checks fail.
> And is also the same for autoconfig.
>
> So the cause of this issue was that you were mistakenly linking a library
> against all libraries and programs being built, and that caused your
> CheckFunction() to yield the wrong result?
>
> -Bill
>
> On Tue, Feb 14, 2017 at 12:25 PM, Pawel Winogrodzki <pawelwi at microsoft.com
> > wrote:
>
>> No, we’re in the middle of a clean-up and stumbled upon this issue.
>>
>>
>>
>> Regardless of ones needs I think the Check* calls should not hide
>> building issues from the developers and make scons assume the build was
>> successful. In addition this also prevents scons from picking up files
>> changes and performing a proper cleanup, when ran with the “-c” option.
>>
>>
>>
>> Thanks,
>>
>> Pawel
>>
>>
>>
>> *From:* Bill Deegan [mailto:bill at baddogconsulting.com]
>> *Sent:* Tuesday, February 14, 2017 09:17
>> *To:* SCons users mailing list <scons-users at scons.org>
>> *Cc:* Pawel Winogrodzki <pawelwi at microsoft.com>
>> *Subject:* Re: [Scons-users] Using CheckFunc() and CheckLib() breaks
>> dependencies and makes scons ignore file changes
>>
>>
>>
>> Any reason you want to have library foo linked against everything you
>> build with your Environment()?
>>
>> -Bill
>>
>>
>>
>> On Tue, Feb 14, 2017 at 2:05 AM, Pawel Winogrodzki via Scons-users <
>> scons-users at scons.org> wrote:
>>
>> Hi all,
>>
>>
>>
>> I think I found a bug in scons and would like to know, if this is already
>> a known issue, and if so, when could a fix be expected. So far I’ve tried
>> scons 2.5.1 and 2.4.1, and got a repro on both.
>>
>>
>>
>> Repro steps for Windows, but this also happens on Linux:
>>
>>    1. Create a simple Environment object “env”.
>>    2. Make it build some library “foo”.
>>    3. Call env.Append(LIBS = [‘foo’]).
>>    4. Create a Configure object “conf” from “env”.
>>    5. Call conf.CheckFunc(‘malloc’) (for instance) and conf.Finish()
>>    (unnecessary for the sake of this example).
>>    6. Use “env” to build an executable “bar”.
>>
>>
>>
>> This will make the CheckFunc() call build “foo.lib” while the script is
>> being executed. As long as the lib is built correctly the developer might
>> not notice any issues, but if the lib fails to build scons will indicate
>> that it finished successfully, even though bar.exe is never created. In
>> addition to that any changes to “foo.c” or any other source file, which was
>> compiled by CheckFunc() will not be noticed by scons. Telling scons to
>> explicitly build “foo.lib” will make scons finish successfully without
>> performing any actions, as long as the lib was already built/failed to
>> build in one of the previous runs of scons.
>>
>>
>>
>> Another side effect is that CheckFunc() will return False, even if the
>> function is available, but the lib failed to build.
>>
>>
>>
>> In the attachment is a sample scons project showing this behavior.
>> Currently it should build “bar.exe” correctly, but in the output scons will
>> not show any indication, that “foo.lib” has been created. You can find that
>> information inside config.log. If you change anything inside “foo.c”, what
>> would prevent it from compiling correctly, you should see the behavior I’ve
>> described above. Of course make sure to clean up between every build.
>> Calling “scons -c” is not enough – you have to delete all other files
>> generated by scons or at least prevent it from using the cache to determine
>> if a function is present on not.
>>
>>
>>
>> Again, please let me know, if this is a known issue and how can I handle
>> it (except for removing all CheckFunc() calls).
>>
>>
>>
>> Thanks,
>>
>> Pawel Winogrodzki
>>
>>
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>>
>>
>>
>
>
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