Document CMP0112 covers $<TARGET_FILE_NAME,tgt>

Fixes #21559

Help/manual/cmake-generator-expressions.7.rst

@@ -648,6 +648,9 @@ which is just the string ``tgt``.
   expression is evaluated on.
 ``$<TARGET_FILE_NAME:tgt>``
   The ``tgt`` filename.
+
+  Note that ``tgt`` is not added as a dependency of the target this
+  expression is evaluated on (see policy :policy:`CMP0112`).
 ``$<TARGET_FILE_DIR:tgt>``
   Directory of the ``tgt`` binary file.
 

Help/policy/CMP0112.rst

@@ -8,6 +8,7 @@ Target file component generator expressions do not add target dependencies.
 The following target-based generator expressions that query for directory or
 file name components no longer add a dependency on the evaluated target.
 
+    - ``TARGET_FILE_NAME``
     - ``TARGET_FILE_DIR``
     - ``TARGET_LINKER_FILE_BASE_NAME``
     - ``TARGET_LINKER_FILE_NAME``