Documentation: gprbuild --build-script

[briot]

README should document that the list of commands can be generated from

 `gprbuild --build-script=smkfile.txt -Pproject.gpr`

That will need two initial compilations: one via gprbuild to get the list of gcc commands, then one via smk so that it detects dependencies.

Another issue with the above is that gprbuilxd passes -gnatem and -gnatec, using temporary files which will no longer exist the next time smk is run. This likely should be reported to AdaCore since I believe the goal of that switch is to produce reproducible builds, which we can't do if they don't explain what they put in those temporary files (mapping and configuration pragmas). If they explain, smk would be able to reproduce that presumably.

[LionelDraghi]

Hello Emmanuel,
I'm not sure to understand why would you use smk instead of gprbuild for rebuild.
Are you sure it would better any performance?
Sound's more complex to me, I'm not sure the balance is in favor of this!

[briot]

You are probably right. I have been fighting with gprbuild a lot lately because it sometimes doesn't recompile as it should, so I was looking around for other application builder tools. Some provide very nice approaches, but they are all missing gprbuild's convenience when it comes to describing a project.
Still, showing --build-script might get people to experiment a bit with smk more easily

[mgrojo]

The same could be said for make -B -n. For simple Makefiles it could work, and it would make sense if one wants to give up with a broken make build.