CMake: config mode of find_package command (examples)

Last update: Dec 14, 2022

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Overview

Install Foo

Install project Foo in Debug and Release variants (Makefile generator):

> cmake -HFoo -B_builds/Foo-debug -DCMAKE_BUILD_TYPE=Debug -DCMAKE_DEBUG_POSTFIX=d -DCMAKE_INSTALL_PREFIX="`pwd`/_install"
> cmake --build _builds/Foo-debug --target install
...
Install the project...
-- Install configuration: "Debug"
-- Installing: /.../_install/lib/libbard.a
-- Installing: /.../_install/lib/libbazd.a
-- Installing: /.../_install/include/foo
-- Installing: /.../_install/include/foo/Bar.hpp
-- Installing: /.../_install/include/foo/Baz.hpp
-- Installing: /.../_install/include/foo/BAR_EXPORT.h
-- Installing: /.../_install/include/foo/BAZ_EXPORT.h
-- Installing: /.../_install/lib/cmake/Foo/FooConfig.cmake
-- Installing: /.../_install/lib/cmake/Foo/FooConfigVersion.cmake
-- Installing: /.../_install/lib/cmake/Foo/FooTargets.cmake
-- Installing: /.../_install/lib/cmake/Foo/FooTargets-debug.cmake

> cmake -HFoo -B_builds/Foo-release -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="`pwd`/_install"
> cmake --build _builds/Foo-release --target install
...
Install the project...
-- Install configuration: "Release"
-- Installing: /.../_install/lib/libbar.a
-- Installing: /.../_install/lib/libbaz.a
-- Up-to-date: /.../_install/include/foo
-- Up-to-date: /.../_install/include/foo/Bar.hpp
-- Up-to-date: /.../_install/include/foo/Baz.hpp
-- Installing: /.../_install/include/foo/BAR_EXPORT.h
-- Installing: /.../_install/include/foo/BAZ_EXPORT.h
-- Installing: /.../_install/lib/cmake/Foo/FooConfig.cmake
-- Installing: /.../_install/lib/cmake/Foo/FooConfigVersion.cmake
-- Installing: /.../_install/lib/cmake/Foo/FooTargets.cmake
-- Installing: /.../_install/lib/cmake/Foo/FooTargets-release.cmake

Note that:

library target bar for different build types has different names: libbar.a and libbard.a
header files is equal for both variants
cmake-config files FooConfig.cmake, FooConfigVersion.cmake and FooTargets.cmake is equal for both variants
FooTargets-release.cmake set Release imported target properties, e.g. IMPORTED_LOCATION_RELEASE
FooTargets-debug.cmake set Debug imported target properties, e.g. IMPORTED_LOCATION_DEBUG

Note:

For -H see: https://cgold.readthedocs.io/en/latest/glossary/-H.html

Boo (use installed Foo)

Easiest way to find and include FooConfig.cmake file is to set CMAKE_INSTALL_PREFIX:

> cmake -HBoo -B_builds/Boo -DCMAKE_INSTALL_PREFIX="`pwd`/_install"

Also CMAKE_PREFIX_PATH and Foo_DIR can be used (do not forget to remove _builds/Boo directory before every configure):

> cmake -HBoo -B_builds/Boo -DCMAKE_PREFIX_PATH="`pwd`/_install"
> cmake -HBoo -B_builds/Boo -DFoo_DIR="`pwd`/_install/lib/cmake/Foo"

find_package config-mode command will include FooConfig.cmake file and import new target Foo::bar:

> cat Boo/CMakeLists.txt 
find_package(Foo CONFIG REQUIRED)
add_executable(boo boo.cpp)
target_link_libraries(boo Foo::bar)

Note that:

definition FOO_BAR_DEBUG will be added automatically
include directory for target Foo::bar will be added automatically
in Debug-mode macro FOO_BAR_DEBUG will be 1 and linker will use libbard.a library
in Release-mode macro FOO_BAR_DEBUG will be 0 and linker will use libbar.a library
if find_package command specify library version then FooConfigVersion.cmake module will check compatibility:

> grep find_package Boo/CMakeLists.txt 
find_package(Foo 2.0 CONFIG REQUIRED)
> cmake -HBoo -B_builds/Boo -DCMAKE_INSTALL_PREFIX="`pwd`/_install"
CMake Error at CMakeLists.txt:8 (find_package):
  Could not find a configuration file for package "Foo" that is compatible
  with requested version "2.0".

The following configuration files were considered but not accepted:

    /.../_install/lib/cmake/Foo/FooConfig.cmake, version: 1.2.3

Script

See jenkins.py script for automatic testing + options --install-boo/--shared and --monolithic.

UML sequence diagram

Comments

Issue Finding Package

I gave your example a try and I like how it is structured as well as how clear and concise the CMake is, but I ran into a problem. I ran install and successfully "installed" the Foo project.

When I try to use Foo::bar and Foo::baz in another project, the find_package fails because the check_components function fails when it's searching for the required components. Any ideas how to fix this so that the components are successfully found? If that check isn't there everything works fine.

opened by DeveloperPaul123 11
Monolithic build works only if commands add_subdirectory are in the right order

Thank you for this example. There is something that does not seem satisfying: the monolithic build works only if the order of commands add_subdirectory in the top-level CMakeLists.txt is correct. Is there not a way to improve on this? (Imagine a set of a dozen libraries with various dependencies between them.)
question

opened by lguez 6
Automating install of third parties packages

I would like to setup third parties project like proposed in this example.

However, I would like that the setup of these third parties package are done by my main project cmake.

If the third party package is not there, then install it .... (most of them are git repository based)

have you got an idea on how to proceed ?

opened by sancelot 3
Use `LIB_INSTALL_DIR`

@mrostecki added this pull request to my project. I asked him to please post it here but I don't think he has had time to do so. I was wondering how you feel about this issue. Below is a quote from the linked PR.

The common practice in cmake to allow to specify the libdir is using the LIB_INSTALL_DIR variable. The main use case of that variable is setting /usr/lib64 as the destination dir for libraries which is a common pattern in many Linux distributions.

opened by isaachier 2
[CMakeLists.txt] Quoting and using name from environment

[.gitignore] Add common ignore formats

PS: Is it just me or is CMake far more complicated and convoluted than is needed? - Maybe I've just been spoiled in the Rust world with Cargo…

opened by SamuelMarks 0