add_library¶
Add a library to the project using the specified source files.
Normal Libraries¶
add_library(<name> [STATIC | SHARED | MODULE]
[EXCLUDE_FROM_ALL]
[<source>...])
Adds a library target called <name> to be built from the source files
listed in the command invocation. 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).
New 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.
New in version 3.11: The source files can be omitted if they are added later using
target_sources().
STATIC, SHARED, or MODULE may be given to specify the type of
library to be created. STATIC libraries are archives of object files
for use when linking other targets. SHARED libraries are linked
dynamically and loaded at runtime. MODULE libraries are plugins that
are not linked into other targets but may be loaded dynamically at runtime
using dlopen-like functionality. If no type is given explicitly the
type is STATIC or SHARED based on whether the current value of the
variable BUILD_SHARED_LIBS is ON. 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.
New 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.
If EXCLUDE_FROM_ALL is given the corresponding property will be set on
the created target. See documentation of the EXCLUDE_FROM_ALL
target property for details.
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.
Object Libraries¶
add_library(<name> OBJECT [<source>...])
Creates an Object Library. An object library
compiles source files but does not archive or link their object files into a
library. Instead 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>.
New in version 3.12: Object libraries can be linked to with target_link_libraries().
Interface Libraries¶
add_library(<name> INTERFACE)
Creates an Interface Library.
An INTERFACE library target does not compile sources and does
not produce a library artifact on disk. 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.
An interface library created with the above signature has no source files itself and is not included as a target in the generated buildsystem.
New 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.
New in version 3.19: An interface library target may be created with source files:
add_library(<name> INTERFACE [<source>...] [EXCLUDE_FROM_ALL])
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.
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])
Creates an IMPORTED library target called <name>.
No rules are generated to build it, and the IMPORTED target
property is True. The target name has scope in the directory in which
it is created and below, but the GLOBAL option extends visibility.
It may be referenced like any target built within the project.
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_.
The <type> must be one of:
STATIC,SHARED,MODULE,UNKNOWNReferences a library file located outside the project. The
IMPORTED_LOCATIONtarget property (or its per-configuration variantIMPORTED_LOCATION_<CONFIG>) specifies the location of the main library file on disk:For a
SHAREDlibrary on most non-Windows platforms, the main library file is the.soor.dylibfile used by both linkers and dynamic loaders. If the referenced library file has aSONAME(or on macOS, has aLC_ID_DYLIBstarting in@rpath/), the value of that field should be set in theIMPORTED_SONAMEtarget property. If the referenced library file does not have aSONAME, but the platform supports it, then theIMPORTED_NO_SONAMEtarget property should be set.For a
SHAREDlibrary on Windows, theIMPORTED_IMPLIBtarget property (or its per-configuration variantIMPORTED_IMPLIB_<CONFIG>) specifies the location of the DLL import library file (.libor.dll.a) on disk, and theIMPORTED_LOCATIONis the location of the.dllruntime library (and is optional, but needed by theTARGET_RUNTIME_DLLSgenerator expression).
Additional usage requirements may be specified in
INTERFACE_*properties.An
UNKNOWNlibrary type is typically only used in the implementation of Find Modules. It allows the path to an imported library (often found using thefind_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.OBJECTReferences a set of object files located outside the project. The
IMPORTED_OBJECTStarget property (or its per-configuration variantIMPORTED_OBJECTS_<CONFIG>) specifies the locations of object files on disk. Additional usage requirements may be specified inINTERFACE_*properties.INTERFACEDoes not reference any library or object files on disk, but may specify usage requirements in
INTERFACE_*properties.
See documentation of the IMPORTED_* and INTERFACE_* 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.
New in version 3.11: An ALIAS can target a GLOBAL Imported Target
New 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.