Without this patch, FILECHECK_OPTS isn't propagated to FileCheck's
test suite so that FILECHECK_OPTS doesn't inadvertently affect test
results by affecting the output of FileCheck calls under test. As a
result, FILECHECK_OPTS is useless for debugging FileCheck's test
suite.
In llvm/test/FileCheck/lit.local.cfg, this patch provides a new
subsitution, %ProtectFileCheckOutput, to address this problem for
both FILECHECK_OPTS and the deprecated
FILECHECK_DUMP_INPUT_ON_FAILURE. The rest of the patch uses
%ProtectFileCheckOutput throughout the test suite
Fixes PR40284.
Instead of that, just add a preceding line with
Likewise everywhere else.
See https://reviews.llvm.org/D65121#1610682.