$ perl -v | head -2 | tail -1
This is perl 5, version 30, subversion 0 (v5.30.0) built for cygwin-thread-multi

$ perl -MO=Deparse -e '$offs = () = /\PM/g;'
$offs = () = /\PM/g;
-e syntax OK

$ perl -MO=Deparse -e '$offs = /^\pM/ + ( () = /\PM/g );'
$offs = /^\pM/ + (() = /\PM/g);
-e syntax OK

$ perl -v | head -2 | tail -1
This is perl 5, version 38, subversion 0 (v5.38.0) built for cygwin-thread-multi

$ perl -MO=Deparse -e '$offs = () = /\PM/g;'
$offs = () = /\PM/g;
-e syntax OK

$ perl -MO=Deparse -e '$offs = /^\pM/ + ( () = /\PM/g );'
$offs = /^\pM/ + (() = /\PM/g);
-e syntax OK