In multi-config generators we memoize the computed set of source files
for a target to avoid repeating the computation when the set does not
depend on the configuration. We already track whether generator
expressions in `SOURCES` or `INTERFACE_SOURCES` reference the
configuration (`$<CONFIG:...>`). However, we previously forgot to track
whether the set of libraries whose `INTERFACE_SOURCES` are considered
depends on the configuration. This caused multi-config generators to
use the first configuration's set of sources for all configurations
in cases such as
target_link_libraries(tgt PRIVATE $<$<CONFIG:Debug>:iface_debug>)
where the `iface_debug` target has `INTERFACE_SOURCES`.
Fix this by also tracking config-dependence of the list of libraries for
evaluation of the list of source files.
Fixes: #20683
Extend the cmGeneratorExpressionDAGChecker with an interface
returning the name of the top target. Use that to determine
when there is a DAG violation, as required by the RunCMake.Languages
tests.
Disallow the use of config-specific source files with
the Visual Studio and Xcode generators. They don't have
any way to represent the condition currently.
Use the same common-config API in cmQtAutoGenerators. While
it accepts config-specific files, it doesn't have to support
multiple configurations yet.
Loop over the configs in cmTargetTraceDependencies
and cmGlobalGenerator::WriteSummary and consume all source
files.
Loop over the configs in cmComputeTargetDepends and compute the
object library dependencies for each config.
