[CMake] Generate sources

[Layus]

Hi,

I am looking for a way to share an archive of a partially compiled 
project to speedup compilation time and configuration hassle for the users.

I have a project that works in two steps.
First a source generator is built (based on clang) and generates some 
extra source files based on the existing source files.
Then the normal compilation process takes places, building the 
application from both original and generated sources.

Here is a pseudo-Makefile.

     application: $GENERATED_SOURCES $SOURCES
         cc $^ -o $@

     $GENERATED_SOURCES: generator $SOURCES
         # generate more sources
         generator $SOURCES

     generate: $GENERATED_SOURCES

     generator: generator.cc clang(external) llvm(external)
         cc $< -o $@ -lclang -lllvm

Of course, all the project is using CMake.

Now, is it possible to distribute a source archive with the generated 
sources, in such a way that any user unpacking the archive and running 
cmake would not have to generate the extra sources ?

This would be useful because
i) the project is tricky to configure and
ii) the generated sources are not dependent on the user config, so 
building the generator is just useless computation time on the user.

The ideal scheme would be something like

     [developper]
     $ cmake -DCLANG=config
     $ make generate
     $ make package_source

     [user]
     $ unpack
     $ cmake -DUSER=config
     $ make # builds only the application, reusing the shipped generated 
sources.
     $ make install

... but when the user runs cmake, he overwrites the generated Makefiles 
and the extra sources are generated again.

Any idea ?

layus.