Using CMake to develop with mongoc lib

Working with Data Drivers
1

Hello, I am still new to CMake and try to use the mongoc driver. I don’t want to use install feature, I just wish to have my dependencies as git submodules in my main git repository.
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This is my folder hierarchy with two dependencies submodules, poco and mongoc.

Then in my top CMake file I add this:

......
add_subdirectory(ThirdParties/poco)
add_subdirectory(ThirdParties/mongo-c-driver)
......
target_link_libraries(tests PUBLIC Poco::Foundation)
target_link_libraries(tests PUBLIC mongo::mongoc_shared)
......

For the last line which links with library mongo_shared, I just copied what I found in the hello_mongo example.
For some reason I’ve not grasped yet, when doing this, I get the following error:

CMake Error at CMakeLists.txt:12 (target_link_libraries):
  Target "tests" links to:

    mongo::mongoc_shared

  but the target was not found.  Possible reasons include:

    * There is a typo in the target name.
    * A find_package call is missing for an IMPORTED target.
    * An ALIAS target is missing.

To fix this, I need to replace “mongo::mongoc_shared” with just “mongoc_shared”, thus removing the namespace mongo, when the same works for namespace Poco.

What did I miss there?

2

I could fake it with an alias like this:

add_library(mongo::mongoc_shared ALIAS mongoc_shared)

so I guess it was the find_package which is ultimately responsible for creating the namespace mongo:: but I could not figure out how, comparing with what Poco does, given I do not use find_package for Poco linking.