FILE_SET: Forbid adding header sets to Apple FRAMEWORK libraries

The feature needs a specialized implementation to place headers
in the right place inside frameworks.  To avoid silently doing
the wrong thing, make this case an error for the 3.23 series.

Issue: #23386

2 files changed, 15 insertions, 1 deletions

diff --git a/Help/command/target_sources.rst b/Help/command/target_sources.rst
index 6ad86e3..1ad6c37 100644
--- a/Help/command/target_sources.rst
+++ b/Help/command/target_sources.rst
@@ -77,7 +77,7 @@ 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.
+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
diff --git a/Help/release/3.23.rst b/Help/release/3.23.rst
index 1a3f53e..257c3d5 100644
--- a/Help/release/3.23.rst
+++ b/Help/release/3.23.rst
@@ -264,3 +264,17 @@ Other Changes
 * :manual:`ccmake(1)` may now be enabled on Windows when building
   CMake from source.  This is experimental, and so is not included
   in official distributions.
+
+Updates
+=======
+
+Changes made since CMake 3.23.0 include the following.
+
+3.23.1
+------
+
+* The :command:`target_sources` ``FILE_SET`` feature added in CMake 3.23.0
+  does not yet place header files properly in Apple :prop_tgt:`FRAMEWORK`
+  targets.  Pending further work in a future version of CMake, it is now
+  an error to add a ``FILE_SET`` of type ``HEADERS`` to such targets on
+  Apple platforms.