Add an `IMPORTED_LIBNAME[_<CONFIG>]` target property to specify a library
name to be placed on the link line in place of an interface library
since it has no library file of its own. Restrict use of the property
to imported `INTERFACE` libraries.
This will be particularly useful for find modules that need to provide
imported libraries from system SDKs where the full path to the library
file is not known. Now such find modules will be able to provide an
imported interface library and set `IMPORTED_LIBNAME` to refer to the
SDK library by name.
Issue: #15267
Revert commit v3.0.0-rc1~175^2~20 (add_dependencies: Disallow use with
INTERFACE_LIBRARY, 2013-12-25). Teach our dependency analysis to
transitively follow INTERFACE target utility dependencies as was done or
IMPORTED targets in commit v2.8.6~127^2~1 (Allow add_dependencies() on
imported targets, 2010-11-19). Extend the InterfaceLibrary test with a
case to cover header generation for a header-only INTERFACE library via
a custom target.
This has to be tested separately from the invalid_signature test because
target sources are evaluate at a later time, and earlier errors in the
invalid_signature test cause early exit.
The INTERFACE_LIBRARY type does not have any LOCATION at all, so
return early from GetMappedConfig. GetMappedConfig is called from
two locations, one of which already pre-checks the INTERFACE_LIBRARY
case. Remove that pre-check and handle that case inside the method
instead.
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.
