Help/variable/CMAKE_LINK_GROUP_USING_FEATURE.txt

It must contain two elements.

::

  <PREFIX> <SUFFIX>

``<PREFIX>`` and ``<SUFFIX>`` will be used to encapsulate the list of
libraries.

For the elements of this variable, the ``LINKER:`` prefix can be used:

  .. include:: ../command/LINK_OPTIONS_LINKER.txt
    :start-line: 3

Examples
^^^^^^^^

Solving cross-references between two static libraries
"""""""""""""""""""""""""""""""""""""""""""""""""""""

A common need is the capability to search repeatedly in a group of static
libraries until no new undefined references are created. This capability is
offered by different environments but with a specific syntax:

.. code-block:: cmake

  set(CMAKE_C_LINK_GROUP_USING_cross_refs_SUPPORTED TRUE)
  if(CMAKE_C_COMPILER_ID STREQUAL "GNU"
     AND CMAKE_SYSTEM_NAME STREQUAL "Linux")
    set(CMAKE_C_LINK_GROUP_USING_cross_refs "LINKER:--start-group"
                                            "LINKER:--end-group")
  elseif(CMAKE_C_COMPILER_ID STREQUAL "SunPro"
         AND CMAKE_SYSTEM_NAME STREQUAL "SunOS")
    set(CMAKE_C_LINK_GROUP_USING_cross_refs "LINKER:-z,rescan-start"
                                            "LINKER:-z,rescan-end")
  else()
    # feature not yet supported for the other environments
    set(CMAKE_C_LINK_GROUP_USING_cross_refs_SUPPORTED FALSE)
  endif()

  add_library(lib1 STATIC ...)

  add_library(lib3 SHARED ...)
  if(CMAKE_C_LINK_GROUP_USING_cross_refs_SUPPORTED)
    target_link_libraries(lib3 PRIVATE "$<LINK_GROUP:cross_refs,lib1,external>")
  else()
    target_link_libraries(lib3 PRIVATE lib1 external)
  endif()

CMake will generate the following link expressions:

* ``GNU``: ``-Wl,--start-group /path/to/lib1.a -lexternal -Wl,--end-group``
* ``SunPro``: ``-Wl,-z,rescan-start /path/to/lib1.a -lexternal -Wl,-z,rescan-end``