llvm/libcxx/test/libcxx/selftest/dsl/lit.local.cfg

# Since we try to pass substitutions as-is to some tests, we must "escape"
# them in case they contain other substitutions. Otherwise, the substitutions
# will be fully expanded when passed to the tests. For example, we want an
# %{exec} substitution that contains `--execdir %T` to be passed as-is, without
# substituting the directory. This way, the test itself can populate %T as it
# sees fit, and %{exec} will respect it.
#
# To solve this problem, we pickle the substitutions and base64 encode that
# to pass it to the test, and we decode and unpickle the substitutions from
# within the test.
import base64, lit.util, pickle

base64Encode = lambda s: lit.util.to_string(base64.b64encode(lit.util.to_bytes(s)))
escapedSubstitutions = base64Encode(pickle.dumps(config.substitutions))
config.substitutions.append(("%{substitutions}", escapedSubstitutions))