Help: Custom OUTPUT and BYPRODUCTS genexes cannot refer to targets

Relates: #21364

Help/command/add_custom_command.rst

@@ -80,8 +80,10 @@ The options are:
   :prop_sf:`GENERATED` files during ``make clean``.
 
   .. versionadded:: 3.20
-    Arguments to ``BYPRODUCTS`` may use
+    Arguments to ``BYPRODUCTS`` may use a restricted set of
     :manual:`generator expressions <cmake-generator-expressions(7)>`.
+    :ref:`Target-dependent expressions <Target-Dependent Queries>` are not
+    permitted.
 
 ``COMMAND``
   Specify the command-line(s) to execute at build time.
@@ -235,8 +237,10 @@ The options are:
   source file property.
 
   .. versionadded:: 3.20
-    Arguments to ``OUTPUT`` may use
+    Arguments to ``OUTPUT`` may use a restricted set of
     :manual:`generator expressions <cmake-generator-expressions(7)>`.
+    :ref:`Target-dependent expressions <Target-Dependent Queries>` are not
+    permitted.
 
 ``USES_TERMINAL``
   .. versionadded:: 3.2

Help/command/add_custom_target.rst

@@ -55,8 +55,10 @@ The options are:
   :prop_sf:`GENERATED` files during ``make clean``.
 
   .. versionadded:: 3.20
-    Arguments to ``BYPRODUCTS`` may use
+    Arguments to ``BYPRODUCTS`` may use a restricted set of
     :manual:`generator expressions <cmake-generator-expressions(7)>`.
+    :ref:`Target-dependent expressions <Target-Dependent Queries>` are not
+    permitted.
 
 ``COMMAND``
   Specify the command-line(s) to execute at build time.

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

@@ -709,6 +709,8 @@ Variable Queries
     properties to avoid side-effects due to the double evaluation of
     these properties.
 
+.. _`Target-Dependent Queries`:
+
 Target-Dependent Queries
 ------------------------