Customizing Linker Search Paths in CMake
Introduction
CMake, a powerful cross-platform build system, provides a convenient way to manage linker search paths for libraries used in your projects. This article explores various methods to customize these paths to optimize linking and improve project portability.Using IMPORTED_NO_SONAME
If an imported library has the IMPORTED_NO_SONAME target property set, CMake may ask the linker to ignore the library's soname when searching for it. To set this property, use the following command in your CMakeLists.txt file:
set_target_properties(imported_library PROPERTIES IMPORTED_NO_SONAME ON)
Determining Search Paths in target_link_libraries
The search path for target_link_libraries is determined by the linker. CMake simply provides the list of libraries to link against, but the linker decides where to find them. To retrieve the exact search paths used by the linker, you can use the following code snippet:
get_target_property(my_target_link_libraries my_target LINK_LIBRARIES) foreach(lib ${my_target_link_libraries}) get_filename_component(lib_path ${lib} PATH) message("Link library ${lib} from path ${lib_path}") endforeach() Localizing Linker Search Paths
To provide localized linker search paths to specific targets, you can use the link_directories command. This allows you to specify additional directories where the linker should search for libraries when building a particular target. To set a link directory, use the following syntax:
link_directories(path1 path2 ...)
Linking to Libraries in Specific Directories
To specify the exact path to a linkable library, you can use the target_link_libraries command and provide the full path to the library file. This ensures that the linker will not search for the library anywhere else, which can be useful for debugging purposes or to avoid potential conflicts with other libraries.
Example Usage
Here's an example CMakeLists.txt that demonstrates these techniques:
set_target_properties(imported_library PROPERTIES IMPORTED_NO_SONAME ON) link_directories(custom_link_directory) target_link_libraries(my_target my_library /path/to/specific_library.so)
Conclusion
Customizing linker search paths in CMake provides flexibility and control over the linking process. By understanding the different methods described in this article, you can effectively manage link dependencies, improve portability, and troubleshoot linking issues in your CMake projects.
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