OS specific instructions in CMAKE: How to?
I am a beginner to CMAKE. Below is a simple cmake file which works well in mingw environment windows. The problem is clearly with target_link_libraries()
function of CMAKE where I am linking libwsock32.a. In windows this works and I get the results.
However, as expected, in Linux, the /usr/bin/ld
will look for -lwsock32
which is NOT there on the Linux OS.
My Problem is: How do I instruct CMAKE to avoid linking wsock32 library in Linux OS???
Any help will be greatly appreciated.
My Simple CMake file:
PROJECT(biourl)
set (${PROJECT_NAME}_headers ./BioSocketAddress.h ./BioSocketBase.h ./BioSocketBuffer.h ./BioSocketCommon.h ./BioSocketListener.h ./BioSocketPrivate.h ./BioSocketStream.h ./BioUrl.h BioDatabase.h )
set (${PROJECT_NAME}_sources BioSocketAddress.C BioSocketBase.C BioSocketCommon.C BioSocketStream.C BioUrl.C BioDatabase.C )
add_library(${PROJECT_NAME} STATIC ${${PROJECT_NAME}_headers} ${${PROJECT_NAME}_sources} )
# linkers
#find_library(ws NAMES wsock32 PATHS ${PROJECT_SOURCE_DIR} NO_SYSTEM_ENVIRONMENT_PATH NO_DEFAULT_PATH)
target_link_libraries(${PROJECT_NAME} bioutils wsock32)
install (TARGETS ${PROJECT_NAME}
RUNTIME DESTINATION bin
LIBRARY DESTINATION lib
ARCHIVE DESTINATION lib/archive )
Solution 1:
Use
if (WIN32)
#do something
endif (WIN32)
or
if (UNIX)
#do something
endif (UNIX)
or
if (MSVC)
#do something
endif (MSVC)
or similar
see CMake Useful Variables and CMake Checking Platform
Solution 2:
Given this is such a common issue, geronto-posting:
if(UNIX AND NOT APPLE)
set(LINUX TRUE)
endif()
# if(NOT LINUX) should work, too, if you need that
if(LINUX)
message(STATUS ">>> Linux")
# linux stuff here
else()
message(STATUS ">>> Not Linux")
# stuff that should happen not on Linux
endif()
CMake boolean logic docs
CMake platform names, etc.
Solution 3:
In General
You can detect and specify variables for several operating systems like that:
Detect Microsoft Windows
if(WIN32)
# for Windows operating system in general
endif()
Or:
if(MSVC OR MSYS OR MINGW)
# for detecting Windows compilers
endif()
Detect Apple MacOS
if(APPLE)
# for MacOS X or iOS, watchOS, tvOS (since 3.10.3)
endif()
Detect Unix and Linux
if(UNIX AND NOT APPLE)
# for Linux, BSD, Solaris, Minix
endif()
Your specific linker issue
To solve your issue with the Windows-specific wsock32
library, just remove it from other systems, like that:
if(WIN32)
target_link_libraries(${PROJECT_NAME} bioutils wsock32)
else
target_link_libraries(${PROJECT_NAME} bioutils)
endif()
Solution 4:
You have some special words from CMAKE, take a look:
if(${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
// do something for Linux
else
// do something for other OS
Solution 5:
Generator expressions are also possible:
target_link_libraries(
target_name
PUBLIC
libA
$<$<PLATFORM_ID:Windows>:wsock32>
PRIVATE
$<$<PLATFORM_ID:Linux>:libB>
libC
)
This will link libA, wsock32 & libC on Windows and link libA, libB & libC on Linux
CMake Generator Expressions