EXCLUDE_FROM_ALL: Don't warn if installing target excluded from all

The original warning pre-dates support for install components.
There are now legitimate scenarios where an install(TARGETS)
command may list a target that is excluded from all, e.g.
hierarchical projects that will never install the component such a
target belongs to.

Fixes: #18938

1 files changed, 10 insertions, 2 deletions

diff --git a/Help/prop_tgt/EXCLUDE_FROM_ALL.rst b/Help/prop_tgt/EXCLUDE_FROM_ALL.rst
index e7457e1..0eee297 100644
--- a/Help/prop_tgt/EXCLUDE_FROM_ALL.rst
+++ b/Help/prop_tgt/EXCLUDE_FROM_ALL.rst
@@ -6,8 +6,16 @@ Exclude the target from the all target.
 A property on a target that indicates if the target is excluded from
 the default build target.  If it is not, then with a Makefile for
 example typing make will cause this target to be built.  The same
-concept applies to the default build of other generators.  Installing
-a target with EXCLUDE_FROM_ALL set to true has undefined behavior.
+concept applies to the default build of other generators.
+
+With ``EXCLUDE_FROM_ALL`` set to false or not set at all, the target
+will be brought up to date as part of doing a ``make install`` or its
+equivalent for the CMake generator being used.  If a target has
+``EXCLUDE_FROM_ALL`` set to true, then any attempt to install that
+target has undefined behavior.  Note that such a target can still safely
+be listed in an :command:`install(TARGETS)` command as long as the install
+components the target belongs to are not part of the set of components
+that anything tries to install.
 
 This property is enabled by default for targets that are created in
 directories that have :prop_dir:`EXCLUDE_FROM_ALL` set to ``TRUE``.