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.
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.
The Config and IMPORTED_ variants may also contain generator
expressions.
If 'the implementation is the interface', then the result of
evaluating the expressions at generate time is used to populate
the IMPORTED_LINK_INTERFACE_LIBRARIES property.
1) In the case of non-static libraries, this is fine because the
user still has the option to populate the LINK_INTERFACE_LIBRARIES
with generator expressions if that is what is wanted.
2) In the case of static libraries, this prevents a footgun,
enforcing that the interface and the implementation are really
the same.
Otherwise, the LINK_LIBRARIES could contain a generator
expression which is evaluated with a different context at build
time, and when used as an imported target. That would mean that the
result of evaluating the INTERFACE_LINK_LIBRARIES property for
a static library would not necessarily be the 'link implementation'.
For example:
add_library(libone STATIC libone.cpp)
add_library(libtwo STATIC libtwo.cpp)
add_library(libthree STATIC libthree.cpp)
target_link_libraries(libtwo
$<$<STREQUAL:$<TARGET_PROPERTY:TYPE>,STATIC_LIBRARY>:libone>)
target_link_libraries(libthree libtwo)
If the LINK_LIBRARIES content was simply copied to the
IMPORTED_LINK_INTERFACE_LIBRARIES, then libthree links to libone, but
executables linking to libthree will not link to libone.
3) As the 'implementation is the interface' concept is to be
deprecated in the future anyway, this should be fine.
Now that we're processing a LINK_INTERFACE_LIBRARIES string, it
can contain targets. Make sure they are extracted for
namespacing purposes.
This needs to be restricted to strings which can actually have
targets named in them. For example, this is not done for
INTERFACE_COMPILE_DEFINITIONS, because even if there is a target
named 'foo', the string 'foo' in that property means that '-Dfoo'
will be set when compiling.
The 'head' is the dependent target to be linked with the current target.
It will be used to evaluate generator expressions with proper handling
of mapped configurations and is used as the source target of properties.
This requires that memoization is done with a key of a pair of target
and config, instead of just config, because now the result also depends
on the target. Removing the memoization entirely is not an option
because it slows cmake down considerably.
The TARGET_NAME expression, which requires a literal, provides
target names. $<TARGET_PROPERTY:tgt,prop> also provides target
names in the cases where tgt is a literal, so that TARGET_NAME is
not needed then in addition.
Previously it was necessary for writers of Config files
which incude exported target files to write the guard themselves, but
this was not immediately obvious or documented. Options for them
would be to use a variable, or an INHERITED directory property in an
effort to avoid accidental name clashes in all contexts in
which find_package can be used.
Getting this right requires boiler plate code, so generate a simpler
check automatically instead.
This way the name of the searched package can be accessed in find-modules,
config-files and more importantly in generated target export files.
This is now used when a target export file detects that a required
target does not exist.
Alex
Before, cmExportFileGenerator::ComplainAboutMissingTarget() was a virtual
function which had to be implemented in the subclasses. It is not
anymore. Instead, there is now a virtual function
HandleMissingTargets(), which is implemented in the two subclasses.
This makes e.g. dealing correctly with APPEND mode easier.
Alex
Now, if an imported target depends on a library which must come
from some other export set, cmake generates a check which errors
out if that target does not exist. I guess instead of completely
erroring out it would be better to only make the find_package() fail.
Alex
If a target is exported, and a library it depends on is not part
of the same export set, before this patch cmake errored out.
With this patch, it now checks whether the missing target
is exported somewhere else exactly once, and accepts in this
case (because then it can determine the namespace for the
missing target and use this).
Alex
Add a boolean target property NO_SONAME which may be used to disable
soname for the specified shared library or module even if the platform
supports it. This property should be useful for private shared
libraries or various plugins which live in private directories and have
not been designed to be found or loaded globally.
Replace references to <CMAKE_SHARED_LIBRARY_SONAME_${LANG}_FLAG> and
hard-coded -install_name flags with a conditional <SONAME_FLAG> which is
expanded to the value of the CMAKE_SHARED_LIBRARY_SONAME_${LANG}_FLAG
definition as long as soname supports is enabled for the target in
question. Keep expanding CMAKE_SHARED_LIBRARY_SONAME_${LANG}_FLAG in
rules in case third party projects still use it. Such projects would
not yet use NO_SONAME so the adjacent <TARGET_SONAME> will always be
expanded. Make <TARGET_INSTALLNAME_DIR> NO_SONAME aware as well. Since
-install_name is soname on OS X, this should not be a problem if this
variable is expanded only if soname is enabled.
The Ninja generator performs rule variable substitution only once
globally per rule to put its own placeholders. Final substitution is
performed by ninja at build time. Therefore we cannot conditionally
replace the soname placeholders on a per-target basis. Rather than
omitting $SONAME from rules.ninja, simply do not write its contents for
targets which have NO_SONAME. Since 3 variables are affected by
NO_SONAME ($SONAME, $SONAME_FLAG, $INSTALLNAME_DIR), set them only if
soname is enabled.
Typical <package>Config.cmake files for find_package() rely only on the
files generated by install(EXPORT). They might be wrong, for whatever
reasons, like people manually deleted files, projects were packaged
wrong by distributions, whatever. To protect against this, add checks
that the file locations we are importing actually exist on disk.
Alex
This converts the CMake license to a pure 3-clause OSI-approved BSD
License. We drop the previous license clause requiring modified
versions to be plainly marked. We also update the CMake copyright to
cover the full development time range.
We create target property "LINK_INTERFACE_MULTIPLICITY" and a per-config
version "LINK_INTERFACE_MULTIPLICITY_<CONFIG>". It sets the number of
times a linker should scan through a mutually dependent group of static
libraries. The largest value of this property on any target in the
group is used. This will help projects link even for extreme cases of
cyclic inter-target dependencies.
Now that languages are part of the link interface of a target we need to
export/import the information. A new IMPORTED_LINK_INTERFACE_LANGUAGES
property and per-config IMPORTED_LINK_INTERFACE_LANGUAGES_<CONFIG>
property specify the information for imported targets. The export() and
install(EXPORT) commands automatically set the properties.
When LINK_INTERFACE_LIBRARIES is not set we use the link implementation
to implicitly define the link interface. These changes centralize the
decision so that all linkable targets internally have a link interface.
- Move runtime path ordering out of cmComputeLinkInformation
into its own class cmOrderRuntimeDirectories.
- Create an instance of cmOrderRuntimeDirectories for runtime
path ordering and another instance for dependent library
path ordering.
- Replace CMAKE_DEPENDENT_SHARED_LIBRARY_MODE with explicit
CMAKE_LINK_DEPENDENT_LIBRARY_FILES boolean.
- Create CMAKE_LINK_DEPENDENT_LIBRARY_DIRS boolean.
- Create variables to specify -rpath-link flags:
CMAKE_SHARED_LIBRARY_RPATH_LINK_<LANG>_FLAG
CMAKE_EXECUTABLE_RPATH_LINK_<LANG>_FLAG
- Enable -rpath-link flag on Linux and QNX.
- Documentation and error message updates
- Split IMPORTED_LINK_LIBRARIES into two parts:
IMPORTED_LINK_INTERFACE_LIBRARIES
IMPORTED_LINK_DEPENDENT_LIBRARIES
- Add CMAKE_DEPENDENT_SHARED_LIBRARY_MODE to select behavior
- Set mode to LINK for Darwin (fixes universal binary problem)
- Update ExportImport test to account for changes
- Shared libs and executables with exports may now have
explicit transitive link dependencies specified
- Created LINK_INTERFACE_LIBRARIES and related properties
- Exported targets get the interface libraries as their
IMPORTED_LINK_LIBRARIES property.
- The export() and install(EXPORT) commands now give
an error when a linked target is not included since
the user can change the interface libraries instead
of adding the target.
- Imported bundles have the MACOSX_BUNDLE property set
- Added cmTarget::IsAppBundleOnApple method to simplify checks
- Document BUNDLE keyword in INSTALL command
- Updated IMPORTED_LOCATION property documentation for bundles
- Updated ExportImport test to test bundles
Stephen Kelly
Brad King
Alex Neundorf
Modestas Vainius
Richard Bateman