1 files changed, 127 insertions, 18 deletions
diff --git a/Help/command/target_sources.rst b/Help/command/target_sources.rst
index 520614a..1ad6c37 100644
--- a/Help/command/target_sources.rst
+++ b/Help/command/target_sources.rst
@@ -15,34 +15,143 @@ Specifies sources to use when building a target and/or its dependents.
 The named ``<target>`` must have been created by a command such as
 :command:`add_executable` or :command:`add_library` or
 :command:`add_custom_target` and must not be an
-:ref:`ALIAS target <Alias Targets>`.
-
-.. versionchanged:: 3.13
-  Relative source file paths are interpreted as being relative to the current
-  source directory (i.e. :variable:`CMAKE_CURRENT_SOURCE_DIR`).
-  See policy :policy:`CMP0076`.
+:ref:`ALIAS target <Alias Targets>`.  The ``<items>`` may use
+:manual:`generator expressions <cmake-generator-expressions(7)>`.
 
 .. versionadded:: 3.20
   ``<target>`` can be a custom target.
 
 The ``INTERFACE``, ``PUBLIC`` and ``PRIVATE`` keywords are required to
-specify the scope of the items following them.  ``PRIVATE`` and ``PUBLIC``
-items will populate the :prop_tgt:`SOURCES` property of
-``<target>``, which are used when building the target itself.
+specify the scope of the source file paths (``<items>``) that follow
+them.  ``PRIVATE`` and ``PUBLIC`` items will populate the :prop_tgt:`SOURCES`
+property of ``<target>``, which are used when building the target itself.
 ``PUBLIC`` and ``INTERFACE`` items will populate the
 :prop_tgt:`INTERFACE_SOURCES` property of ``<target>``, which are used
-when building dependents.
-The following arguments specify sources.  Repeated calls for the same
-``<target>`` append items in the order called. The targets created by
-:command:`add_custom_target` can only have ``PRIVATE`` scope.
+when building dependents.  A target created by :command:`add_custom_target`
+can only have ``PRIVATE`` scope.
+
+Repeated calls for the same ``<target>`` append items in the order called.
 
 .. versionadded:: 3.3
   Allow exporting targets with :prop_tgt:`INTERFACE_SOURCES`.
 
 .. versionadded:: 3.11
-  Allow setting ``INTERFACE`` items on :ref:`IMPORTED targets <Imported Targets>`.
+  Allow setting ``INTERFACE`` items on
+  :ref:`IMPORTED targets <Imported Targets>`.
+
+.. versionchanged:: 3.13
+  Relative source file paths are interpreted as being relative to the current
+  source directory (i.e. :variable:`CMAKE_CURRENT_SOURCE_DIR`).
+  See policy :policy:`CMP0076`.
+
+A path that begins with a generator expression is left unmodified.
+When a target's :prop_tgt:`SOURCE_DIR` property differs from
+:variable:`CMAKE_CURRENT_SOURCE_DIR`, use absolute paths in generator
+expressions to ensure the sources are correctly assigned to the target.
+
+.. code-block:: cmake
+
+  # WRONG: starts with generator expression, but relative path used
+  target_sources(MyTarget "$<$<CONFIG:Debug>:dbgsrc.cpp>")
+
+  # CORRECT: absolute path used inside the generator expression
+  target_sources(MyTarget "$<$<CONFIG:Debug>:${CMAKE_CURRENT_SOURCE_DIR}/dbgsrc.cpp>")
+
+See the :manual:`cmake-buildsystem(7)` manual for more on defining
+buildsystem properties.
+
+File Sets
+^^^^^^^^^
+
+.. versionadded:: 3.23
+
+.. code-block:: cmake
+
+  target_sources(<target>
+    [<INTERFACE|PUBLIC|PRIVATE>
+     [FILE_SET <set> [TYPE <type>] [BASE_DIRS <dirs>...] [FILES <files>...]]...
+    ]...)
+
+Adds a file set to a target, or adds files to an existing file set. Targets
+have zero or more named file sets. Each file set has a name, a type, a scope of
+``INTERFACE``, ``PUBLIC``, or ``PRIVATE``, one or more base directories, and
+files within those directories. The only acceptable type is ``HEADERS``. The
+optional default file sets are named after their type. The target may not be a
+custom target or :prop_tgt:`FRAMEWORK` target.
+
+Files in a ``PRIVATE`` or ``PUBLIC`` file set are marked as source files for
+the purposes of IDE integration. Additionally, files in ``HEADERS`` file sets
+have their :prop_sf:`HEADER_FILE_ONLY` property set to ``TRUE``. Files in an
+``INTERFACE`` or ``PUBLIC`` file set can be installed with the
+:command:`install(TARGETS)` command, and exported with the
+:command:`install(EXPORT)` and :command:`export` commands.
+
+Each ``target_sources(FILE_SET)`` entry starts with ``INTERFACE``, ``PUBLIC``, or
+``PRIVATE`` and accepts the following arguments:
+
+``FILE_SET <set>``
+
+  The name of the file set to create or add to. It must contain only letters,
+  numbers and underscores. Names starting with a capital letter are reserved
+  for built-in file sets predefined by CMake. The only predefined set name is
+  ``HEADERS``. All other set names must not start with a capital letter or
+  underscore.
+
+``TYPE <type>``
+
+  Every file set is associated with a particular type of file. ``HEADERS``
+  is currently the only defined type and it is an error to specify anything
+  else. As a special case, if the name of the file set is ``HEADERS``, the
+  type does not need to be specified and the ``TYPE <type>`` arguments can be
+  omitted. For all other file set names, ``TYPE`` is required.
+
+``BASE_DIRS <dirs>...``
+
+  An optional list of base directories of the file set. Any relative path
+  is treated as relative to the current source directory
+  (i.e. :variable:`CMAKE_CURRENT_SOURCE_DIR`). If no ``BASE_DIRS`` are
+  specified when the file set is first created, the value of
+  :variable:`CMAKE_CURRENT_SOURCE_DIR` is added. This argument supports
+  :manual:`generator expressions <cmake-generator-expressions(7)>`.
+
+  No two base directories for a file set may be sub-directories of each other.
+  This requirement must be met across all base directories added to a file set,
+  not just those within a single call to ``target_sources()``.
+
+``FILES <files>...``
+
+  An optional list of files to add to the file set. Each file must be in
+  one of the base directories, or a subdirectory of one of the base
+  directories. This argument supports
+  :manual:`generator expressions <cmake-generator-expressions(7)>`.
+
+  If relative paths are specified, they are considered relative to
+  :variable:`CMAKE_CURRENT_SOURCE_DIR` at the time ``target_sources()`` is
+  called. An exception to this is a path starting with ``$<``. Such paths
+  are treated as relative to the target's source directory after evaluation
+  of generator expressions.
+
+The following target properties are set by ``target_sources(FILE_SET)``,
+but they should not generally be manipulated directly:
+
+* :prop_tgt:`HEADER_SETS`
+* :prop_tgt:`INTERFACE_HEADER_SETS`
+* :prop_tgt:`HEADER_SET`
+* :prop_tgt:`HEADER_SET_<NAME>`
+* :prop_tgt:`HEADER_DIRS`
+* :prop_tgt:`HEADER_DIRS_<NAME>`
+
+Target properties related to include directories are also modified by
+``target_sources(FILE_SET)`` as follows:
+
+:prop_tgt:`INCLUDE_DIRECTORIES`
+
+  If the ``TYPE`` is ``HEADERS``, and the scope of the file set is ``PRIVATE``
+  or ``PUBLIC``, all of the ``BASE_DIRS`` of the file set are wrapped in
+  :genex:`$<BUILD_INTERFACE>` and appended to this property.
+
+:prop_tgt:`INTERFACE_INCLUDE_DIRECTORIES`
 
-Arguments to ``target_sources`` may use "generator expressions"
-with the syntax ``$<...>``. See the :manual:`cmake-generator-expressions(7)`
-manual for available expressions.  See the :manual:`cmake-buildsystem(7)`
-manual for more on defining buildsystem properties.
+  If the ``TYPE`` is ``HEADERS``, and the scope of the file set is
+  ``INTERFACE`` or ``PUBLIC``, all of the ``BASE_DIRS`` of the file set are
+  wrapped in :genex:`$<BUILD_INTERFACE>` and appended to this property.