add_library

Add a library to the project using the specified source files.

Normal Libraries

add_library(<name> [<type>] [EXCLUDE_FROM_ALL] <sources>...)

Add a library target called <name> to be built from the source files listed in the command invocation.

The optional <type> specifies the type of library to be created:

STATIC

An archive of object files for use when linking other targets.

SHARED

A dynamic library that may be linked by other targets and loaded at runtime.

MODULE

A plugin that may not be linked by other targets, but may be dynamically loaded at runtime using dlopen-like functionality.

If no <type> is given the default is STATIC or SHARED based on the value of the BUILD_SHARED_LIBS variable.

The options are:

EXCLUDE_FROM_ALL

Set the EXCLUDE_FROM_ALL target property automatically. See documentation of that target property for details.

The <name> corresponds to the logical target name and must be globally unique within a project. The actual file name of the library built is constructed based on conventions of the native platform (such as lib<name>.a or <name>.lib).

Added in version 3.1: Source arguments to add_library may use "generator expressions" with the syntax $<...>. See the cmake-generator-expressions(7) manual for available expressions.

Added in version 3.11: The source files can be omitted if they are added later using target_sources().

For SHARED and MODULE libraries the POSITION_INDEPENDENT_CODE target property is set to ON automatically. A SHARED library may be marked with the FRAMEWORK target property to create an macOS Framework.

Added in version 3.8: A STATIC library may be marked with the FRAMEWORK target property to create a static Framework.

If a library does not export any symbols, it must not be declared as a SHARED library. For example, a Windows resource DLL or a managed C++/CLI DLL that exports no unmanaged symbols would need to be a MODULE library. This is because CMake expects a SHARED library to always have an associated import library on Windows.

By default the library file will be created in the build tree directory corresponding to the source tree directory in which the command was invoked. See documentation of the ARCHIVE_OUTPUT_DIRECTORY, LIBRARY_OUTPUT_DIRECTORY, and RUNTIME_OUTPUT_DIRECTORY target properties to change this location. See documentation of the OUTPUT_NAME target property to change the <name> part of the final file name.

See the cmake-buildsystem(7) manual for more on defining buildsystem properties.

See also HEADER_FILE_ONLY on what to do if some sources are pre-processed, and you want to have the original sources reachable from within IDE.

Changed in version 3.30: On platforms that do not support shared libraries, add_library now fails on calls creating SHARED libraries instead of automatically converting them to STATIC libraries as before. See policy CMP0164.

Object Libraries

add_library(<name> OBJECT <sources>...)

Add an Object Library to compile source files without archiving or linking their object files into a library.

Other targets created by add_library or add_executable() may reference the objects using an expression of the form $<TARGET_OBJECTS:objlib> as a source, where objlib is the object library name. For example:

add_library(... $<TARGET_OBJECTS:objlib> ...)
add_executable(... $<TARGET_OBJECTS:objlib> ...)

will include objlib's object files in a library and an executable along with those compiled from their own sources. Object libraries may contain only sources that compile, header files, and other files that would not affect linking of a normal library (e.g. .txt). They may contain custom commands generating such sources, but not PRE_BUILD, PRE_LINK, or POST_BUILD commands. Some native build systems (such as Xcode) may not like targets that have only object files, so consider adding at least one real source file to any target that references $<TARGET_OBJECTS:objlib>.

Added in version 3.12: Object libraries can be linked to with target_link_libraries().

Interface Libraries

add_library(<name> INTERFACE)

Add an Interface Library target that may specify usage requirements for dependents but does not compile sources and does not produce a library artifact on disk.

An interface library with no source files is not included as a target in the generated buildsystem. However, it may have properties set on it and it may be installed and exported. Typically, INTERFACE_* properties are populated on an interface target using the commands:

and then it is used as an argument to target_link_libraries() like any other target.

Added in version 3.15: An interface library can have PUBLIC_HEADER and PRIVATE_HEADER properties. The headers specified by those properties can be installed using the install(TARGETS) command.

add_library(<name> INTERFACE [EXCLUDE_FROM_ALL] <sources>...)

Added in version 3.19.

Add an Interface Library target with source files (in addition to usage requirements and properties as documented by the above signature). Source files may be listed directly in the add_library call or added later by calls to target_sources() with the PRIVATE or PUBLIC keywords.

If an interface library has source files (i.e. the SOURCES target property is set), or header sets (i.e. the HEADER_SETS target property is set), it will appear in the generated buildsystem as a build target much like a target defined by the add_custom_target() command. It does not compile any sources, but does contain build rules for custom commands created by the add_custom_command() command.

The options are:

EXCLUDE_FROM_ALL

Set the EXCLUDE_FROM_ALL target property automatically. See documentation of that target property for details.

Note

In most command signatures where the INTERFACE keyword appears, the items listed after it only become part of that target's usage requirements and are not part of the target's own settings. However, in this signature of add_library, the INTERFACE keyword refers to the library type only. Sources listed after it in the add_library call are PRIVATE to the interface library and do not appear in its INTERFACE_SOURCES target property.

Imported Libraries

add_library(<name> <type> IMPORTED [GLOBAL])

Add an IMPORTED library target called <name>. The target name may be referenced like any target built within the project, except that by default it is visible only in the directory in which it is created, and below.

The <type> must be one of:

STATIC, SHARED, MODULE, UNKNOWN

References a library file located outside the project. The IMPORTED_LOCATION target property (or its per-configuration variant IMPORTED_LOCATION_<CONFIG>) specifies the location of the main library file on disk:

  • For a SHARED library on most non-Windows platforms, the main library file is the .so or .dylib file used by both linkers and dynamic loaders. If the referenced library file has a SONAME (or on macOS, has a LC_ID_DYLIB starting in @rpath/), the value of that field should be set in the IMPORTED_SONAME target property. If the referenced library file does not have a SONAME, but the platform supports it, then the IMPORTED_NO_SONAME target property should be set.

  • For a SHARED library on Windows, the IMPORTED_IMPLIB target property (or its per-configuration variant IMPORTED_IMPLIB_<CONFIG>) specifies the location of the DLL import library file (.lib or .dll.a) on disk, and the IMPORTED_LOCATION is the location of the .dll runtime library (and is optional, but needed by the TARGET_RUNTIME_DLLS generator expression).

Additional usage requirements may be specified in INTERFACE_* properties.

An UNKNOWN library type is typically only used in the implementation of Find Modules. It allows the path to an imported library (often found using the find_library() command) to be used without having to know what type of library it is. This is especially useful on Windows where a static library and a DLL's import library both have the same file extension.

OBJECT

References a set of object files located outside the project. The IMPORTED_OBJECTS target property (or its per-configuration variant IMPORTED_OBJECTS_<CONFIG>) specifies the locations of object files on disk. Additional usage requirements may be specified in INTERFACE_* properties.

INTERFACE

Does not reference any library or object files on disk, but may specify usage requirements in INTERFACE_* properties.

The options are:

GLOBAL

Make the target name globally visible.

No rules are generated to build imported targets, and the IMPORTED target property is True. Imported libraries are useful for convenient reference from commands like target_link_libraries().

Details about the imported library are specified by setting properties whose names begin in IMPORTED_ and INTERFACE_. See documentation of such properties for more information.

Alias Libraries

add_library(<name> ALIAS <target>)

Creates an Alias Target, such that <name> can be used to refer to <target> in subsequent commands. The <name> does not appear in the generated buildsystem as a make target. The <target> may not be an ALIAS.

Added in version 3.11: An ALIAS can target a GLOBAL Imported Target

Added in version 3.18: An ALIAS can target a non-GLOBAL Imported Target. Such alias is scoped to the directory in which it is created and below. The ALIAS_GLOBAL target property can be used to check if the alias is global or not.

ALIAS targets can be used as linkable targets and as targets to read properties from. They can also be tested for existence with the regular if(TARGET) subcommand. The <name> may not be used to modify properties of <target>, that is, it may not be used as the operand of set_property(), set_target_properties(), target_link_libraries() etc. An ALIAS target may not be installed or exported.

See Also