While porting boost to use these features, the generation step took
too long (several minutes before I stopped it). The reason was that
the boost libraries form a large interdependent mesh. The libraries
list their dependencies in their INTERFACE such as:
$<LINKED:boost::core>;$<LINKED:boost::config>;$<LINKED:boost::mpl>
As boost::core already depends on the boost::config libraries, that
expression has no impact on the end-content, as it is removed after
the generation step. There is no DAG issue though, so the generator
expression evaluation would fully evaluate them. In the case of the
config library, it also depends on the core library, so all depends
are followed through that again, despite the fact that they've just
been evaluated. After this patch, the evaluation skips libraries if
they have already been seen via depends or directly in the content.
This patch keeps track of targets whose INTERFACE has been consumed
already. The INCLUDE_DIRECTORIES and COMPILE_DEFINITIONS properties
are whitelisted because repeated content will be stripped out later
during generation. For other properties now and in the future, that
may not be the case.
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.
Both commit 8a37ebec (Add the target_include_directories command,
2013-01-01) and commit fc61a7a7 (Add the target_compile_definitions
command, 2013-01-08) added command implementations deriving from the new
cmTargetPropCommandBase class. Fix cmTypeMacro declarations of the
inheritance relationship.
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.
With similar reasoning to the parent commit, as downstreams, we can't
determine what $<CONFIG> generator expressions would be appropriate.
Upstream would have populated the INTERFACE_INCLUDE_DIRECTORIES with
config-specific generator expressions, possibly appropriate for
their DEBUG_CONFIGURATIONS. In theory, if we would add include
directories for a DEBUG intent, we would have to match the upstream
configurations for that.
Rather than attempting to discover the appropriate configurations
at this time, simplify the feature instead. The use of IMPORTED targets
with these commands could still be added in the future if targets
would export their DEBUG_CONFIGURATIONS somehow.
This reverts commit 9cfe4f1b76.
It turns out that correctly adding the content to
the IMPORTED_LINK_INTERFACE_LIBARIES_<CONFIG> of an upstream target
from the buildsystem of a downstream project is not simple.
If upstream had added the INTERFACE content, the config-specific
properties would be determined by the DEBUG_CONFIGURATIONS of
upstream.
As downstream, we don't have any information about what
the DEBUG_CONFIGURATIONS of upstream were, so we can't determine
which configuration-specific properties to populate. The best we can do
is add it to all of them or add it to the ones downstream considers to
be DEBUG_CONFIGURATIONS, neither of which is a good solution.
So, removing the porcelain API for that is the best approach. A human
can still determine which properties to populate and use
the set_property API to populate the desired properies.
Another solution to this would be for upstream targets to publish
what they consider DEBUG_CONFIGURATIONS, but that can be added in
a future release.
During configure-time, GetIncludeDirectories may be called too, for example
if using the export() command. As the content can be different, it should
be output each time then.
Otherwise, we get a separate IncludeDirectoriesEntry for each include,
and that causes unnecessary and confusing splitting in the output when
debugging the INCLUDE_DIRECTORIES property.
The cache here needs to be cleared if GetLinkInformation is called
at configure-time, such as during an export().
The next commit does exactly that, and without this patch,
the LinkLanguage test would fail.
It is not necessary and the current state is unintentional. Before
this patch,
target_link_libraries(foo bar)
causes the LINK_LIBRARIES property of foo to contain
$<TARGET_NAME:bar>
instead of just
bar
This new expression allows checking how a policy was set when a target
was created. That information is only recorded for a subset of policies,
so a whitelist is used.
1d74ba2 Test evaluation target via export for generator expressions
522bdac Export the INTERFACE_PIC property.
4ee872c Make the BUILD_INTERFACE of export()ed targets work.
1d47cd9 Add a test for the interfaces in targets exported from the build tree.
6c828f9 Move the exported check for file existence.
cfd4f0a Move the exported check for dependencies of targets
d8fe1fc Only generate one check per missing target.
f623d37 Don't write a comment in the export file without the code.
b279f2b Strip consecutive semicolons when preprocessing genex strings.
Stephen Kelly
Kitware Robot
Brad King
Alex Neundorf
Rolf Eike Beer
Yury G. Kudryashov
Robert Maynard