Please see the below minimal example

cmake_minimum_required(VERSION 3.20)

project(sample)

add_library(libA A.cpp A.h)
add_library(libB B.cpp B.h)
add_executable(${PROJECT_NAME} main.cpp)

# Given it is known that libA and libB is incompatible, 
# is it possible to write some extra cmake code to show error while doing cmake config,
# instead of having to compile to discover the error?
target_link_libraries(${PROJECT_NAME} libA libB) --> need to show error  

# target_link_libraries(${PROJECT_NAME} libA) --> ok
# target_link_libraries(${PROJECT_NAME} libB) --> ok

Given that I can't alter the source of libA and libB to make them compatible, how can I discover the error earlier in the CMake configuration stage instead of having to compile the huge codebase to find out the error?

CodePudding user response：

Yes! This is actually possible using a little-known feature called Compatible Interface Properties.

You'll define a custom property with an arbitrary name. Here I'll call it ABI_GROUP and use two different GUIDs for the values. Then you'll add that property to COMPATIBLE_INTERFACE_STRING. See the code below:

cmake_minimum_required(VERSION 3.23)
project(example)

add_library(libA A.cpp A.h)
set_property(TARGET libA PROPERTY INTERFACE_ABI_GROUP "5c6142b9-9b60-4327-bd71-122bd29a9646")
set_property(TARGET libA APPEND PROPERTY COMPATIBLE_INTERFACE_STRING ABI_GROUP)

add_library(libB B.cpp B.h)
set_property(TARGET libB PROPERTY INTERFACE_ABI_GROUP "e291a3cd-50e4-44dc-a90c-66899d34bde5")
set_property(TARGET libB APPEND PROPERTY COMPATIBLE_INTERFACE_STRING ABI_GROUP)

add_executable(example main.cpp)
target_link_libraries(example PRIVATE libA libB)

This results in the following error:

CMake Error: The INTERFACE_ABI_GROUP property of "libB" does
not agree with the value of ABI_GROUP already determined
for "example".

The values of all properties in the COMPATIBLE_INTERFACE_STRING list must either be empty or match among the transitive set of targets that are linked together. There are also a few other modes:

• COMPATIBLE_INTERFACE_BOOL - same as string, but tolerant to "truthy" values, i.e. ON and 1 are considered compatible
• COMPATIBLE_INTERFACE_NUMBER_MAX - the property evaluates to the largest number among the transitive target set.
• COMPATIBLE_INTERFACE_NUMBER_MIN - same as above, but smallest