CMake link to external library

Question

How to get CMake to link an executable to an external shared library that is not build within the same CMake project   Just doing target link libraries GLBall   CMAKE BINARY DIR  res mylib so  gives the error  make 2       No rule to make target  res mylib so   needed by  GLBall    Stop  make 1        CMakeFiles GLBall dir all  Error 2 make       all  Error 2  GLBall is the executable    after I copied the library into the binary dir bin res   I tried using find library RESULT mylib so PATHS   CMAKE BINARY DIR  res   Which fails with RESULT-NOTFOUND

User · Accepted Answer

Set libraries search path first   LINK DIRECTORIES   CMAKE BINARY DIR  res    And then just do  TARGET LINK LIBRARIES GLBall mylib

User · Answer

One more alternative  in the case you are working with the Appstore  need  Entitlements  and as such need to link with an Apple-Framework   For Entitlements to work  e g  GameCenter  you need to have a  Link Binary with Libraries -buildstep and then link with  GameKit framework   CMake  injects  the libraries on a  low level  into the commandline  hence Xcode doesn t really know about it  and as such you will not get GameKit enabled in the Capabilities screen   One way to use CMake and have a  Link with Binaries -buildstep is to generate the xcodeproj with CMake  and then use  sed  to  search  amp  replace  and add the GameKit in the way XCode likes it      The script looks like this  for Xcode 6 3 1    s      Begin PBXBuildFile section           Begin PBXBuildFile section           26B12AA11C10544700A9A2BA      GameKit framework in Frameworks         isa   PBXBuildFile  fileRef   26B12AA01C10544700A9A2BA      GameKit framework xxx         g  s      Begin PBXFileReference section           Begin PBXFileReference section           26B12AA01C10544700A9A2BA      GameKit framework xxx        isa   PBXFileReference  lastKnownFileType   wrapper framework  name   GameKit framework  path   System  Library  Frameworks  GameKit framework  sourceTree   SDKROOT     g  s      End PBXFileReference section           End PBXFileReference section              Begin PBXFrameworksBuildPhase section           26B12A9F1C10543B00A9A2BA      Frameworks                   isa   PBXFrameworksBuildPhase           buildActionMask   2147483647           files                  26B12AA11C10544700A9A2BA      GameKit framework in Frameworks xxx                           runOnlyForDeploymentPostprocessing   0                End PBXFrameworksBuildPhase section        g  s      CMake PostBuild Rules            CMake PostBuild Rules                    26B12A9F1C10543B00A9A2BA      Frameworks xxx      g s      Products            Products                    26B12AA01C10544700A9A2BA      GameKit framework xxx      g   save this to  gamecenter sed  and then  apply  it like this   it changes your xcodeproj     sed -i pbxprojbak -f gamecenter sed myproject xcodeproj project pbxproj   You might have to change the script-commands to fit your need   Warning  it s likely to break with different Xcode-version as the project-format could change  the  hardcoded  unique number might not really by unique - and generally the solutions by other people are better - so unless you need to Support the Appstore   Entitlements  and automated builds   don t do this   This is a CMake bug  see http   cmake org Bug view php id 14185 and http   gitlab kitware com cmake cmake issues 14185

User · Answer

I assume you want to link to a library called foo  its filename is usually something link foo dll or libfoo so   1  Find the library You have to find the library  This is a good idea  even if you know the path to your library  CMake will error out if the library vanished or got a new name  This helps to spot error early and to make it clear to the user  may yourself  what causes a problem  To find a library foo and store the path in FOO LIB use      find library FOO LIB foo    CMake will figure out itself how the actual file name is  It checks the usual places like  usr lib   usr lib64 and the paths in PATH   You already know the location of your library  Add it to the CMAKE PREFIX PATH when you call CMake  then CMake will look for your library in the passed paths  too   Sometimes you need to add hints or path suffixes  see the documentation for details  https   cmake org cmake help latest command find library html  2  Link the library From 1  you have the full library name in FOO LIB  You use this to link the library to your target GLBall as in    target link libraries GLBall PRIVATE    FOO LIB      You should add PRIVATE  PUBLIC  or INTERFACE after the target  cf  the documentation  https   cmake org cmake help latest command target link libraries html  If you don t add one of these visibility specifiers  it will either behave like PRIVATE or PUBLIC  depending on the CMake version and the policies set   3  Add includes  This step might be not mandatory   If you also want to include header files  use find path similar to find library and search for a header file  Then add the include directory with target include directories similar to target link libraries   Documentation  https   cmake org cmake help latest command find path html and https   cmake org cmake help latest command target include directories html  If available for the external software  you can replace find library and find path by find package

User · Answer

arrowdodger s answer is correct and preferred on many occasions  I would simply like to add an alternative to his answer   You could add an  imported  library target  instead of a link-directory  Something like     Your-external  mylib   add GLOBAL if the imported library is located in directories above the current  add library  mylib SHARED IMPORTED     You can define two import-locations  one for debug and one for release  set target properties  mylib PROPERTIES IMPORTED LOCATION   CMAKE BINARY DIR  res mylib so     And then link as if this library was built by your project   TARGET LINK LIBRARIES GLBall mylib    Such an approach would give you a little more flexibility  Take a look at the add library    command and the many target-properties related to imported libraries   I do not know if this will solve your problem with  updated versions of libs

[cmake] CMake link to external library

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