Currently, export() is executed at configure-time.
One problem with this is that certain exported properties like
the link interface may not be complete at the point the export() is
encountered leading to an incorrect or incomplete exported
representation. Additionally, the generated IMPORTED_LOCATION
property may even be incorrect if commands following the export()
have an effect on it.
Another problem is that it requires the C++ implementation of cmake
to be capable of computing the exported information at configure time.
This is a limitation on the cleanup and maintenance of the code. At
some point in the future, this limitation will be dropped and more
implementation will be moved from cmTarget to cmGeneratorTarget.
Previously CMake silently accepted the empty string and added a bogus
dependency on the current directory. Instead warn about the empty file
name and ignore it. We cannot make this an error because there may be
existing projects that accidentally depend on the old behavior.
Add a RunCMake.include test to cover this case.
Stephen Kelly
Brad King