Problem with CMake Generation

[MultiplexLayout]

I am working on a project that looks like this:

./
CMakeLists.txt

externals/
|---CMakeLists.txt
|---boost/
|---dynatmic/
|---|---CMakeLists.txt

Note that the boost directory doesn't have a CMakeLists.txt. Its sources are set in externals/CMakeLists.txt.

Relevant part of root CMakeLists.txt

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add_subdirectory(externals)
add_library(Boost::boost ALIAS boost)

Relevant part of externals/CMakelists.txt

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set(BOOST_ROOT "${CMAKE_SOURCE_DIR}/externals/boost" CACHE STRING "")
set(Boost_INCLUDE_DIR "${CMAKE_SOURCE_DIR}/externals/boost" CACHE STRING "")
set(Boost_NO_SYSTEM_PATHS ON CACHE BOOL "")
add_library(boost INTERFACE)
target_include_directories(boost SYSTEM INTERFACE ${Boost_INCLUDE_DIR})

The problem:
What I want is to move the ALIAS line from the root CMakeLists.txt to the one in externals/. However when I move this line and run cmake I get:

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-- Configuring done (1.2s)
CMake Error: install(EXPORT "dynarmicTargets" ...) includes target "dynarmic" which requires target "boost" that is not in any export set.
-- Generating done (0.2s)
CMake Generate step failed.  Build files cannot be regenerated correctly.

Relevant part of externals/dynarmic/CMakeLists.txt

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install(TARGETS dynarmic EXPORT dynarmicTargets)
install(EXPORT dynarmicTargets
    NAMESPACE dynarmic::
    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/dynarmic"
)

I just don't understand how dynarmic can "see" the ALIAS line when it's in the root CMakeLists (2 levels above it), but not when it's in externals/ (1 level above it). I have tried adding EXCLUDE_FROM_ALL to add_library(boost INTERFACE) and removing it from add_subdirectory(dynarmic EXCLUDE_FROM_ALL). I just don't know what else to try. Any help would be greatly appreciated.

[mrnordio2]

Hello MultiplexLayout,

The issue seems to be related to the scope of the Boost::boost alias. When you define an alias in the root CMakeLists.txt, it becomes available to all subdirectories, making it visible to dynarmic. However, if you move it to externals/CMakeLists.txt, its scope becomes limited to externals and its subdirectories, but not to dynarmic.

Method 1:
Use add_subdirectory for dynarmic inside externals/CMakeLists.txt

If you add dynarmic as a subdirectory inside externals/CMakeLists.txt, after defining the alias, the alias will be in scope for dynarmic. Modify externals/CMakeLists.txt like this:

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set(BOOST_ROOT "${CMAKE_SOURCE_DIR}/externals/boost" CACHE STRING "")
set(Boost_INCLUDE_DIR "${CMAKE_SOURCE_DIR}/externals/boost" CACHE STRING "")
set(Boost_NO_SYSTEM_PATHS ON CACHE BOOL "")
add_library(boost INTERFACE)
add_library(Boost::boost ALIAS boost)
target_include_directories(boost SYSTEM INTERFACE ${Boost_INCLUDE_DIR})

add_subdirectory(dynarmic)

Method 2:
Use target_link_libraries in dynarmic/CMakeLists.txt

Another way is to explicitly link dynarmic to boost in dynarmic/CMakeLists.txt:

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target_link_libraries(dynarmic PRIVATE Boost::boost)

Ensure that Boost::boost is defined before this line. This makes sure that dynarmic knows about Boost::boost.



Either method should resolve the issue you're facing. I hope this helps!

Best regards,
MrNordio

[MultiplexLayout]

Thank you for responding.

externals/CMakeLists.txt already adds the dynarmic submodule. I'm sorry for not being clearer

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set(DYNARMIC_TESTS OFF CACHE BOOL "")
set(DYNARMIC_FRONTENDS "A32" CACHE STRING "")
set(DYNARMIC_USE_PRECOMPILED_HEADERS ${CITRA_USE_PRECOMPILED_HEADERS} CACHE BOOL "")
add_subdirectory(dynarmic EXCLUDE_FROM_ALL)

I have tried it without the EXCLUDE_FROM_ALL with no effect.

This is what I don't understand. The Boost::boost target should be in scope, but just isn't for some reason. As for method 2, the dynarmic directory is an external submodule, so I don't have any control over it. I'm going to try moving the submodule one directory down and having a new CMakeLists.txt on the level where it used to be.