Instead of executing tests from within the libc++ test suite, we execute
them from the Lit execution directory. However, since some tests have
file dependencies, we must copy those dependencies to the execution
directory where they are executed.
This has the major benefit that if a test modifies a file (whether it
is wanted or not), other tests will not see those modifications. This
is good because current tests assume that input data is never modified,
however this could be an incorrect assumption if some test does not
behave properly.
This makes it closer to how one would run the tests by hand, and it is
also closer to how the SSHExecutor runs the tests remotely. It also
allows using shell builtins in .sh.cpp tests when using %{exec}.
Before this patch, the %run substitution did not contain the same
environment variables as normal `pass.cpp` tests. It also didn't
have the right working directory and the script wasn't aware of
potential file dependencies.
With this change, the combination of %build and %run in a .sh.cpp script
should match how pass.cpp tests are actually executed much more closely.
Louis Dionne