Bug/allow rebuilds with scikit build

[robertmaynard]

Currently due to the implicit logic around SKBUILD it isn't possible for projects to safely build/install multiple times in a row.

Consider a project that looks like:

legate_add_cpp_subdirectory(cpp TARGET legate_user EXPORT legate_user-export)
legate_default_python_install(legate_user EXPORT legate_user-export)

When a local user runs scikit-build the first time everything will work correctly as legate_user doesn't exist in the install location. But when invoked a second time it will find the installed version, and not build. So to install an updated version
of the files you need to first clean your env which is not a nice pattern.

So with the PR, projects can explicitly state they always want to build from source and never search for a local version.

[jjwilke]

@robertmaynard
Thanks for catching this!

You mean the find_package below will pick up the installed version instead of the build tree version?

rapids_find_package(${target} CONFIG
      GLOBAL_TARGETS legate::${target}
      BUILD_EXPORT_SET ${LEGATE_OPT_EXPORT}
      INSTALL_EXPORT_SET ${LEGATE_OPT_EXPORT})

I don't think we would ever want that find package to find an installed version. Should I just restrict the find package call to only look in the build tree? I forget what the option is. NO_DEFAULT_PATH or something.

[robertmaynard]

@robertmaynard Thanks for catching this!

You mean the find_package below will pick up the installed version instead of the build tree version?

rapids_find_package(${target} CONFIG
      GLOBAL_TARGETS legate::${target}
      BUILD_EXPORT_SET ${LEGATE_OPT_EXPORT}
      INSTALL_EXPORT_SET ${LEGATE_OPT_EXPORT})

I don't think we would ever want that find package to find an installed version. Should I just restrict the find package call to only look in the build tree? I forget what the option is. NO_DEFAULT_PATH or something.

Yes you are finding the installed version, yes NO_DEFAULT_PATH would disable those search paths.

I don't recommend naively using the build directory to find the exact package you are building. For example if the user is building and editing the project. After the second execution of CMake they will now find the build directory copy of the project, and won't be able to build it anymore.