Prior to this commit, linking against an object library did not
propagate private link dependencies of object libraries to their
consuming targets. This change implements the correct behavior.
Fixes: #18692
Co-Author: Brad King <brad.king@kitware.com>
Note: This finally links the object-files of the `OBJECT` library from
the right-hand side of `target_link_libraries` to the target on the
left-hand side. However, this will only happen with directly linked
`OBJECT` libraries, not with `OBJECT` libraries "linked" through
property `INTERFACE_LINK_LIBRARIES` of a target on the right-hand side!
Fixes: #14778
Note: This still does not link the object-files of the `OBJECT` library
from the right-hand side of `target_link_libraries` to the target on the
left-hand side. (In this particular case of another `OBJECT` library on
the left-hand side this would not make any sense anyway. The target on
the left-hand side has no link-step.)
Issue: #14778
Note: This only allows `OBJECT` libraries to be on the right-hand side
of `target_link_libraries` but still does not link its object-files to
the target on the left-hand side.
Issue: #14778
The proper way to use libraries is now through `target_link_libraries`
for things such as usage requirements, compile definitions, include
directories, etc. To facilitate this, allow `OBJECT` libraries to "link"
to other libraries.
Co-Author: Ben Boeckel <ben.boeckel@kitware.com>
Issue: #14778
Teach the `install` and `export` commands to support installing and
exporting `OBJECT` libraries without their object files. Transform
them to `INTERFACE` libraries in such cases.
For `install(TARGETS)`, activate this when no destination for the object
files is specified. For `export`, activate this only under Xcode with
multiple architectures when we have no well-defined object file
locations to give to clients.
The code
add_library(A OBJECT a.c)
target_sources(A PRIVATE $<TARGET_OBJECTS:A>)
used to crash CMake via infinite recursion while evaluating the
generator expression. Then the change in commit v3.9.0-rc1~266^2~1
(cmGeneratorTarget: Replace source classifier implementation,
2017-04-07) avoided the infinite recursion because GetKindedSources now
creates a map entry and initializes it once. If it is called again on
the same target during that initialization, the partially computed
results are returned. This is still wrong but does not crash.
Detect and diagnose this case instead.
Co-Author: Ben Boeckel <ben.boeckel@kitware.com>
Fixes: #16578
Teach install() and export() to handle the actual object files.
Disallow this on Xcode with multiple architectures because it
still cannot be cleanly supported there.
Co-Author: Brad King <brad.king@kitware.com>
Teach cmGlobalGenerator::CheckTargets to include OBJECT_LIBRARY targets
in the check for source file existence.
Extend the RunCMake.ObjectLibrary test to cover this case.
It was a subtest of the RunCMake.ObjectLibrary test. However, we need
to test a build with ExternalProject after running CMake, which RunCMake tests
do not do.
Teach the RunCMake.ObjectLibrary test to verify that languages used in
an OBJECT library are propagated to targets that use it so that the
languages can be included in link analysis.
Add "RunCMake.ObjectLibrary" test to verify that unsupported use cases
are rejected with errors:
* An OBJECT library may not reference another object library
* An OBJECT library may not be referenced in target_link_libraries
* An OBJECT library may not contain non-compiling sources
* An OBJECT library may not have pre/post build/link commands
* An OBJECT library may not be installed, exported, or imported
Also verify that invalid $<TARGET_OBJECTS:...> expressions are
diagnosed.
