Improve deployment as subdirectory

[fmoessbauer]

I'm really sorry, that my last PR broke the subdirectory integration support.
For that, we have to include the generated header in the public "build interface" as well... Doing CMake right is ridiculously hard.

As the this issue now happened the second time, I added a test to check the deployment as well:

• as a subdirectory
• using the install target

I'm still a bit unsure where to place these scripts. Maybe we should unify that, once you are done with reworking the testing anyways.

[offa]

I'm really sorry, that my last PR broke the subdirectory integration support.
For that, we have to include the generated header in the public "build interface" as well... Doing CMake right is ridiculously hard.

No Problem. A general CMake question: Is it possible to map $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/src> through a target? So eg. internal parts can consume it using target_link_libraries()?

As the this issue now happened the second time, I added a test to check the deployment as well:

as a subdirectory
using the install target

Adding a test is a good idea! 👍 It's hard to notice otherwise. But instead of executing those step in each compiler build, it's probably a good idea to add a dedicated "deployment" build. Or some more if necessary – eg. subdirectory deployment and make install separated if that makes sense. Those build can skip the tests and stick to a single compiler.

So we keep jobs doing only one task at a time and the deployment tests don't have to forcefully fit into the build & test cycle. Furthermore it becomes easy to spot whether a build failure is deployment or build related.

I'm still a bit unsure where to place these scripts. Maybe we should unify that, once you are done with reworking the testing anyways.

Agreed. For now I'd say the scripts/ directory or alternatively a test_package subdirectory. We can move it later anyway 😄.

[fmoessbauer]

No Problem. A general CMake question: Is it possible to map $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/src> through a target? So eg. internal parts can consume it using target_link_libraries()?

I don't think that is possible. If you export something as PUBLIC, all transitive targets inherit this. I thought about that as well for making an "internal" lib / object lib for testing.

Adding a test is a good idea! It's hard to notice otherwise. But instead of executing those step in each compiler build, it's probably a good idea to add a dedicated "deployment" build. Or some more if necessary – eg. subdirectory deployment and make install separated if that makes sense. Those build can skip the tests and stick to a single compiler.

So we keep jobs doing only one task at a time and the deployment tests don't have to forcefully fit into the build & test cycle. Furthermore it becomes easy to spot whether a build failure is deployment or build related.

As its relatively cheap I would keep it this way. By that, we also test the various install options w/ w/o boost. And another problem is that we have to test the subdir option before we install the target, as otherwise we cannot be sure that the the headers are actually taken from the subdir and not from the system include.

Anyways, feel free to change the CI stuff ;)

[offa]

Thanks!