[gdal-dev] Why can't find_package(GDAL CONFIG) find GDAL_LIBRARIES?

[Even Rouault]

Tom,

GDAL_LIBRARIES and GDAL_INCLUDE_DIRS are indeed not defined. You have to 
use the "GDAL::GDAL" target in a
target_link_libraries() statement which propagates both include and 
linking requirements and tends to be the modern CMake practice, although 
admitedly not very clearly documented in target_link_libraries() 
official documentation. I found 
https://schneide.blog/2016/04/08/modern-cmake-with-target_link_libraries/ 
which deal with that.

So a typical minimum CMakeLists.txt of a project using GDAL is (this is 
actually 
https://github.com/OSGeo/gdal/blob/master/autotest/postinstall/test_c/CMakeLists.txt 
used in GDAL continuous integration to test usage of GDAL from a 
third-party library/application)

"""

cmake_minimum_required(VERSION 3.0)

project(test_c C CXX) # CXX for properly linking GDAL

find_package(GDAL CONFIG REQUIRED)

add_executable(test_c test_c.c)
target_link_libraries(test_c PRIVATE GDAL::GDAL)

"""

I've created https://github.com/OSGeo/gdal/issues/5875 to track we need 
documenting that.

Note: If you really wanted to get the equivalent of GDAL_INCLUDE_DIRS 
and GDAL_LIBRARIES, you could use the following expressions:

$<TARGET_PROPERTY:GDAL::GDAL,INTERFACE_INCLUDE_DIRECTORIES>

$<TARGET_PROPERTY:GDAL::GDAL,INTERFACE_LINK_LIBRARIES>


Even


Le 07/06/2022 à 02:02, Tom O'Reilly a écrit :
> I've just built and installed GDAL 3.5.0 on ubuntu 20.04, with cmake 
> 3.5.0 and make. It appears that 'make install' installs needed cmake 
> config files for GDAL:
>
>     -- Installing:
>     /usr/local/lib/x86_64-linux-gnu/cmake/gdal/GDALConfigVersion.cmake
>     -- Installing:
>     /usr/local/lib/x86_64-linux-gnu/cmake/gdal/GDALConfig.cmake
>
> I'm building my own project that uses GDAL. The CMakelists.txt invokes 
> find_package() and prints out resulting variables:
>
>     find_package(GDAL CONFIG REQUIRED)
>
>     if (GDAL_FOUND)
>       message("GDAL Found!")
>       message("GDAL_INCLUDE_DIRS: ${GDAL_INCLUDE_DIRS}")
>       message("GDAL_LIBRARIES: ${GDAL_LIBRARIES}")
>       message("GDAL_VERSION: ${GDAL_VERSION}")
>     else()
>       message("GDAL not found")
>     endif()
>
> Running cmake indicates that GDAL_FOUND is true, GDAL_VERSION is set 
> to the expected value(3.5.0), but GDAL_LIBRARIES and GDAL_INCLUDE_DIRS 
> are empty:
>
>     GDAL Found!
>     GDAL_INCLUDE_DIRS:
>     GDAL_LIBRARIES:
>     GDAL_LIBRARY:
>     GDAL_VERSION: 3.5.0
>
> Why are GDAL_LIBRARIES and GDAL_INCLUDE_DIR empty?
>
> Thanks
> Tom
>
>
>
> --------------------------------------------------
> Thomas C. O'Reilly
> Monterey Bay Aquarium Research Institute
> 7700 Sandholdt Road
> Moss Landing, California 95039-9644
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>
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>
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>      "Wind, Sand, and Stars" (1939)
>
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