This target type only contains INTERFACE_* properties, so it can be
used as a structural node. The target-specific commands enforce
that they may only be used with the INTERFACE keyword when used
with INTERFACE_LIBRARY targets. The old-style target properties
matching LINK_INTERFACE_LIBRARIES_<CONFIG> are always ignored for
this target type.
The name of the INTERFACE_LIBRARY must match a validity generator
expression. The validity is similar to that of an ALIAS target,
but with the additional restriction that it may not contain
double colons. Double colons will carry the meaning of IMPORTED
or ALIAS targets in CMake 2.8.13.
An ALIAS target may be created for an INTERFACE library.
At this point it can not be exported and does not appear in the
buildsystem and project files are not created for them. That may
be added as a feature in a later commit.
The generators need some changes to handle the INTERFACE_LIBRARY
targets returned by cmComputeLinkInterface::GetItems. The Ninja
generator does not use that API, so it doesn't require changes
related to that.
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.
This library type can compile sources to object files but does not link
or archive them. It will be useful to reference from executable and
normal library targets for direct inclusion of object files in them.
Diagnose and reject the following as errors:
* An OBJECT library may not be referenced in target_link_libraries.
* An OBJECT library may contain only compiling sources and supporting
headers and custom commands. Other source types that are not normally
ignored are not allowed.
* An OBJECT library may not have PRE_BUILD, PRE_LINK, or POST_BUILD
commands.
* An OBJECT library may not be installed, exported, or imported.
Some of these cases may be supported in the future but are not for now.
Teach the VS generator that OBJECT_LIBRARY targets are "linkable" just
like STATIC_LIBRARY targets for the LinkLibraryDependencies behavior.
Since commit 183b9509 (Follow all dependencies of shared library private
dependencies, 2011-12-14) we honor LINK_INTERFACE_LIBRARIES when
following dependent shared libraries. The link interface properties may
form a cycle if set incorrectly by a project. Furthermore, the property
LINK_DEPENDENT_LIBRARIES may form a cycle if set incorrectly by hand
(though CMake should never generate one). In either case, do not follow
the cycle forever when following the dependent shared library closure.
We only need to add dependency edges to the constraint graph once.
Add "LinkInterfaceLoop" test to cover this case.
In cmComputeLinkDepends we compute the transitive closure of private
shared library dependencies. When a shared library is added to this
closure we must follow all of its dependencies whether they are private
or public. Previously we only followed the private dependencies. Fix
the implementation to follow the public dependencies too. Also extend
the ExportImport test to cover this case.
Utility dependencies are "strong" because they must be enforced to
generate a working build. Link dependencies are "weak" because they can
be broken in the case of a static library cycle.
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.
The new method centralizes loops that process raw OriginalLinkLibraries
to extract the link implementation (libraries linked into the target)
for each configuration. Results are computed on demand and then cached.
This simplifies link interface computation because the default case
trivially copies the link implementation.
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.
This moves code implementing policy CMP0004 into cmTarget::CheckCMP0004.
The implementation is slightly simpler and can be re-used outside of
cmComputeLinkDepends.
The transitive link dependencies of a linked target must be followed in
its own scope, not in the scope of the original target that depends on
it. This is necessary since imported targets do not have global scope.
See issue #8843.
The recent fix to avoid including flags in dependency inferral also
dropped them from chaining of dependencies through targets. This fix
restores chaining of flags through known dependency lists while still
leaving them out of inferred dependency lists.
This change introduces a new algorithm for link line construction. The
order it computes always begins with the exact link line specified by
the user. Dependencies of items specified by the user are tracked, and
those that are not already satisified by the line are appended to it at
the end with minimal repeats. This restores the behavior of CMake 2.4
and below while still fixing some of its bugs. See issue #7546.
In cmComputeLinkDepends link items that look like flags (starting in
'-') should not be included in dependency inferral. They are not
libraries and therefore have no dependencies. They should just be
passed through to the final link line unchanged. See issue #7546.
When creating an IMPORTED target for a library that has been found on
disk, it may not be known whether the library is STATIC or SHARED.
However, the library may still be linked using the file found from disk.
Use of an IMPORTED target is still important to allow per-configuration
files to be specified for the library.
This change creates an UNKNOWN type for IMPORTED library targets. The
IMPORTED_LOCATION property (and its per-config equivalents) specifies
the location of the library. CMake makes no assumptions about the
library that cannot be inferred from the file on disk. This will help
projects and find-modules import targets found on disk or specified by
the user.
When an executable target within the project is named in
target_link_libraries for another target, but the executable does not
have the ENABLE_EXPORTS property set, then the executable cannot really
be linked. This is probably a case where the user intends to link to a
third-party library that happens to have the same name as an executable
target in the project (or else will get an error at build time). We
need to avoid making the other target depend on the executable target
incorrectly, since the executable may actually want to link to that
target and this is not a circular depenency.
In CMake 2.4 the generated link line for a target always preserved the
originally specified libraries in their original order. Dependencies
were satisfied by inserting extra libraries into the line, though it had
some bugs. In CMake 2.6.0 we preserved only the items on the link line
that are not known to be shared libraries. This reduced excess
libraries on the link line. However, since we link to system libraries
(such as /usr/lib/libm.so) by asking the linker to search (-lm), some
linkers secretly replace the library with a static library in another
implicit search directory (developers can override this by using an
imported target to force linking by full path). When this happens the
order still matters.
To avoid this and other potential subtle issues this commit restores
preservation of all non-target items and static library targets. This
will create cases of unnecessary, duplicate shared libraries on the link
line if the user specifies them, but at least it will work. In the
future we can attempt a more advanced analysis to safely remove
duplicate shared libraries from the link line.
We preserve the order and multiplicity of libraries directly linked by a
target as specified by the user. Items known to be shared libraries may
be safely skipped because order preservation is only needed for static
libraries. However, CMake 2.4 did not skip shared libs, so we do the
same when in 2.4 compatibility mode.
- CMake 2.4 added link directories for targets linked
in the optimized configuration even when building debug
- Old behavior for policy CMP0003 must account for this
- Move Tarjan algorithm from cmComputeTargetDepends
into its own class cmComputeComponentGraph
- Use cmComputeComponentGraph to identify the component DAG
of link dependencies in cmComputeLinkDepends
- Emit non-trivial component members more than once but always
in a contiguous group on the link line
- 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.
- Created cmExportFileGenerator hierarchy to implement export file generation
- Installed exports use per-config import files loaded by a central one.
- Include soname of shared libraries in import information
- Renamed PREFIX to NAMESPACE in INSTALL(EXPORT) and EXPORT() commands
- Move addition of CMAKE_INSTALL_PREFIX to destinations to install generators
- Import files compute the installation prefix relative to their location when loaded
- Add mapping of importer configurations to importee configurations
- Rename IMPORT targets to IMPORTED targets to distinguish from windows import libraries
- Scope IMPORTED targets within directories to isolate them
- Place all properties created by import files in the IMPORTED namespace
- Document INSTALL(EXPORT) and EXPORT() commands.
- Document IMPORTED signature of add_executable and add_library
- Enable finding of imported targets in cmComputeLinkDepends
- This will be useful for imported library dependencies
- Replaces old cmTarget analyze-lib-depends stuff for linking
- Formalizes graph construction and dump
- Explicitly represents dependency inferral sets
- Use BFS of initial dependencies to preserve order
Stephen Kelly
Brad King
Yury G. Kudryashov
Modestas Vainius