CMake/Help/command/target_link_libraries.rst

target_link_libraries
---------------------

Link a target to given libraries.

::

  target_link_libraries(<target> [item1 [item2 [...]]]
                        [[debug|optimized|general] <item>] ...)

Specify libraries or flags to use when linking a given target.  The
named <target> must have been created in the current directory by a
command such as add_executable or add_library.  The remaining
arguments specify library names or flags.  Repeated calls for the same
<target> append items in the order called.

If a library name matches that of another target in the project a
dependency will automatically be added in the build system to make
sure the library being linked is up-to-date before the target links.
Item names starting with '-', but not '-l' or '-framework', are
treated as linker flags.

A "debug", "optimized", or "general" keyword indicates that the
library immediately following it is to be used only for the
corresponding build configuration.  The "debug" keyword corresponds to
the Debug configuration (or to configurations named in the
DEBUG_CONFIGURATIONS global property if it is set).  The "optimized"
keyword corresponds to all other configurations.  The "general"
keyword corresponds to all configurations, and is purely optional
(assumed if omitted).  Higher granularity may be achieved for
per-configuration rules by creating and linking to IMPORTED library
targets.  See the IMPORTED mode of the add_library command for more
information.

Library dependencies are transitive by default with this signature.
When this target is linked into another target then the libraries
linked to this target will appear on the link line for the other
target too.  This transitive "link interface" is stored in the
INTERFACE_LINK_LIBRARIES target property when policy CMP0022 is set to
NEW and may be overridden by setting the property directly.
(When CMP0022 is not set to NEW, transitive linking is builtin but may
be overridden by the LINK_INTERFACE_LIBRARIES property.  Calls to other
signatures of this command may set the property making any libraries
linked exclusively by this signature private.)

CMake will also propagate "usage requirements" from linked library
targets.  Usage requirements affect compilation of sources in the
<target>.  They are specified by properties defined on linked targets.
During generation of the build system, CMake integrates usage
requirement property values with the corresponding build properties
for <target>:

::

 INTERFACE_COMPILE_DEFINITONS: Appends to COMPILE_DEFINITONS
 INTERFACE_INCLUDE_DIRECTORIES: Appends to INCLUDE_DIRECTORIES
 INTERFACE_POSITION_INDEPENDENT_CODE: Sets POSITION_INDEPENDENT_CODE
   or checked for consistency with existing value



If an <item> is a library in a Mac OX framework, the Headers directory
of the framework will also be processed as a "usage requirement".
This has the same effect as passing the framework directory as an
include directory.

::

  target_link_libraries(<target>
                      <PRIVATE|PUBLIC|INTERFACE> <lib> ...
                      [<PRIVATE|PUBLIC|INTERFACE> <lib> ... ] ...])

The PUBLIC, PRIVATE and INTERFACE keywords can be used to specify both
the link dependencies and the link interface in one command.
Libraries and targets following PUBLIC are linked to, and are made
part of the link interface.  Libraries and targets following PRIVATE
are linked to, but are not made part of the link interface.  Libraries
following INTERFACE are appended to the link interface and are not
used for linking <target>.

::

  target_link_libraries(<target> LINK_INTERFACE_LIBRARIES
                        [[debug|optimized|general] <lib>] ...)

The LINK_INTERFACE_LIBRARIES mode appends the libraries to the
INTERFACE_LINK_LIBRARIES target property instead of using them for
linking.  If policy CMP0022 is not NEW, then this mode also appends
libraries to the LINK_INTERFACE_LIBRARIES and its per-configuration
equivalent.  This signature is for compatibility only.  Prefer the
INTERFACE mode instead.  Libraries specified as "debug" are wrapped in
a generator expression to correspond to debug builds.  If policy
CMP0022 is not NEW, the libraries are also appended to the
LINK_INTERFACE_LIBRARIES_DEBUG property (or to the properties
corresponding to configurations listed in the DEBUG_CONFIGURATIONS
global property if it is set).  Libraries specified as "optimized" are
appended to the INTERFACE_LINK_LIBRARIES property.  If policy CMP0022
is not NEW, they are also appended to the LINK_INTERFACE_LIBRARIES
property.  Libraries specified as "general" (or without any keyword)
are treated as if specified for both "debug" and "optimized".

::

  target_link_libraries(<target>
                        <LINK_PRIVATE|LINK_PUBLIC>
                          [[debug|optimized|general] <lib>] ...
                        [<LINK_PRIVATE|LINK_PUBLIC>
                          [[debug|optimized|general] <lib>] ...])

The LINK_PUBLIC and LINK_PRIVATE modes can be used to specify both the
link dependencies and the link interface in one command.  This
signature is for compatibility only.  Prefer the PUBLIC or PRIVATE
keywords instead.  Libraries and targets following LINK_PUBLIC are
linked to, and are made part of the INTERFACE_LINK_LIBRARIES.  If
policy CMP0022 is not NEW, they are also made part of the
LINK_INTERFACE_LIBRARIES.  Libraries and targets following
LINK_PRIVATE are linked to, but are not made part of the
INTERFACE_LINK_LIBRARIES (or LINK_INTERFACE_LIBRARIES).

The library dependency graph is normally acyclic (a DAG), but in the
case of mutually-dependent STATIC libraries CMake allows the graph to
contain cycles (strongly connected components).  When another target
links to one of the libraries CMake repeats the entire connected
component.  For example, the code

::

  add_library(A STATIC a.c)
  add_library(B STATIC b.c)
  target_link_libraries(A B)
  target_link_libraries(B A)
  add_executable(main main.c)
  target_link_libraries(main A)

links 'main' to 'A B A B'.  (While one repetition is usually
sufficient, pathological object file and symbol arrangements can
require more.  One may handle such cases by manually repeating the
component in the last target_link_libraries call.  However, if two
archives are really so interdependent they should probably be combined
into a single archive.)

Arguments to target_link_libraries may use "generator expressions"
with the syntax "$<...>".  Note however, that generator expressions
will not be used in OLD handling of CMP0003 or CMP0004.
See the :manual:`cmake-generator-expressions(7)` manual for available
expressions.