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

[Bill Deegan]

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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