On 15.03.2016 23:01, Julien Schueller wrote:
Hi,
When using find_package (<name> NO_MODULE) while cross-compiling,
cmake may find an existing <name>Config.cmake in the host root path if
<name>Config.cmake is not available in the target root path.
For example let's say that I have Qt5 project in my host Linux box,
which provides a /usr/lib/cmake/.../Qt5WidgetsConfig.cmake.
In my cmake project I use: find_package (Qt5Widgets NO_MODULE),
everything goes as planned.
Now I want to cross-compile using MinGW-w64, I install qt5 in my mingw
target root, so I have a
/usr/i686-w64-mingw32/lib/cmake/.../Qt5WidgetsConfig.cmake
I set CMAKE_FIND_ROOT_PATH to /usr/i686-w64-mingw32 and stuff via a
toolchain file, and everything goes fine too.
No if I remove the qt5 target package for mingw, or it is unavailable
in the first place, cmake prefers the host qt5 config file, and the
compilation fails.
I found a workaround, which is to not let cmake use host rules to find
<name>Config.cmake in the case of cross-compiling:
if (CMAKE_CROSSCOMPILING)
set (NO_MODULE_ARGS NO_MODULE NO_SYSTEM_ENVIRONMENT_PATH
NO_CMAKE_SYSTEM_PATH)
endif ()
find_package (Qt5Widgets ${NO_MODULE_ARGS})
Would there be a smarter way to do this instead of invading each
CMakeLists that uses a find_package relying on package-provided cmake
configs ?
Setting
https://cmake.org/cmake/help/v3.5/variable/CMAKE_FIND_ROOT_PATH_MODE_PACKAGE.html
to ONLY in your toolchain file should prevent cmake from picking up
native packages.
Nils
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