This establishes that linking is used to propagate usage-requirements
between targets in CMake code. The use of the target_link_libraries
command as the API for this is chosen because introducing a new command
would introduce confusion due to multiple commands which differ only in
a subtle way.
This is both a short form of using a TARGET_DEFINED expression
together with a TARGET_PROPERTY definition, and a way to strip
non-target content from interface properties when exporting.
Projects set interface requirements upstream, and existing
downstreams use of target_link_libraries will consume those interfaces.
This can create a backward compatibility concern as the result may
be changing the order of include directories of downstreams, or another
side-effect of using the INTERFACE properties.
Provide a way for them to emulate the behavior of a version-based
policy in the config file.
7bf490e Make subclasses responsible for joining content.
f6b16d4 Don't allow targets args in the new target commands.
b3a7e19 Make the Property name protected so that subclasses can use it.
We need to make sure we can export targets which have content such
as $<0:$<TARGET_PROPERTY:not_a_target,INTERFACE_INCLUDE_DIRECTORIES>
That means making not finding a target non-fatal here.
Explain in the documentation for the legacy signature
target_link_libraries(foo bar)
that the other signatures like
target_link_libraries(foo LINK_INTERFACE_LIBRARIES ...)
target_link_libraries(foo LINK_PRIVATE ...)
will set the LINK_INTERFACE_LIBRARIES target property and therefore make
libraries specified only by the legacy signature private.
These interface-related link-libraries properties are used to determine
the value of the other INTERFACE properties, so we were getting infinite
recursion and segfaults otherwise.
6063fef Output include directories as LOG messages, not warnings.
aa66748 Specify the target whose includes are being listed.
d70204a Only output includes once after the start of 'generate-time' when debugging.
0d46e9a Store includes from the same include_directories call together.
830246e Export the COMPATIBLE_INTERFACE_BOOL content properties
bd82bb4 Clear the link information in ClearLinkMaps.
e987991 Make INTERFACE determined properties readable in generator expressions.
d9afacc Exit early if we find an inconsistent property.
1800f70 Populate the link information cache before checking dependent properties.
Stephen Kelly
Brad King
Kitware Robot
Alex Neundorf
Rolf Eike Beer
Yury G. Kudryashov