Perl See also design.
XXX in comments in source code is used to mark important unfinished work, XX is used for "should probably be improved, but not essential under normal working conditions". In text files, 'todo' is used.
perltidy v20200110 is used to format all Perl code. To have this done automatically for each commit, run cd .git/hooks && ln -s ../../meta/pre-commit.
Tests that depend on the Perl core being fixed are only run if the TEST_PERL env variable is true. I.e. run
TEST_PERL=1 make test
or similar.