[CMake] How to deal with generated source files (w/ dependency tracking) for globs

[Nicholas Braden]

I haven't tested this myself, but instead of using a glob, you could
have a build step that generates a CMake script file with the list of
generated files in it (e.g. via execute_process to run another CMake
script whose only job is to generate the CMake script inception-style)
and just include the generated file - CMake will see that the CMake
file has been modified during every build but will still handle source
file changes correctly. Worth a shot.

On Mon, Apr 4, 2016 at 6:36 PM, Eric Wing <ewmailing at gmail.com> wrote:
> Hi, this is kind of a side problem that was asked of me. I'm not sure
> how many hoops I actually want to jump through to solve this. But,
> here's the situation.
>
> I have a really nice, traditional C based project in CMake. All my
> dependency tracking works really well for cross-platform and IDE
> integration and even have resources/bundling/codesigning working
> nicely in the single build step.
>
> Now somebody throws me a curve ball and wants to use the Nim language.
> The specifics of the Nim language itself is not that important to this
> topic, but the key piece of information is that the Nim compiler can
> generate C files as output.
>
> So the question is, how can I invoke Nim to compile a list of
> pre-known Nim source files, and then slurp in the generated output C
> files and build them as part of my normal CMake build process.
>
> The curve ball is this: I don't know all the names or how many files
> the Nim compiler generates. If I know all the names beforehand, I
> think I know how to deal with this situation. But instead, I get a
> directory of C files. The names seem to be dependent on which library
> features were used and also what the user's source files were named. I
> suspect the standard library could theoretically change too so future
> versions of Nim may have different files.
>
> I know file globs with CMake don't auto-track changes and I think the
> problem gets more trickier because of the indirection to invoke Nim.
> (i.e. When I first glob the files, the directory is empty, then the
> Nim compiler is invoked later and the files appear, but it is too late
> for CMake to see without a regeneration).
>
> Anyway, I was wondering what the best approach is.
>
> Thanks,
> Eric
> --
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