perl - What is the function of PMLIBPARENTDIRS in ExtUtils::MakeMaker? -

perl - What is the function of PMLIBPARENTDIRS in ExtUtils::MakeMaker? -

one of our projects has ancient, inherited makefile.pl based on extutils::makemaker contains following:

writemakefile( # ... many lines omitted ... pmlibdirs => [ 'lib', '$(baseext)' ], pmlibparentdirs => [ 'lib' ], );

the pmlibdirs alternative explained in documentation (linked above), pmlibparentdirs not documented can find. mentioned twice in source code however, not in appears functional way (i.e. in configuration , documentation).

commenting out pmlibparentdirs alternative not have obvious negative impact when building package.

what parameter do? or obsolete?

perl build makemaker