in reply to Re^2: if modifier of a print statement
in thread if modifier of a print statement

The first one is interpreted as:
print $_ . ("\n" && next) if /no_proc/;

The  . operator has higher precedence than the  && operator so it is actually interpreted as:

$ perl -MO=Deparse,-p -e' print $_ . "\n" && next if /no_proc/; ' (/no_proc/ and print((($_ . "\n") && next))); -e syntax OK