Looks like a bug to me, whatever special casing .... doesn't happen the same way with grep

$ perl -Mre=debug -le " @F = qw( a b c DBIC A B C DANCER a b c ); for( +@F){print if /DBIC/.. /DANCER/ and ! // } " Compiling REx "DBIC" Final program: 1: EXACT <DBIC> (3) 3: END (0) anchored "DBIC" at 0 (checking anchored isall) minlen 4 Compiling REx "DANCER" Final program: 1: EXACT <DANCER> (4) 4: END (0) anchored "DANCER" at 0 (checking anchored isall) minlen 6 Compiling REx "" Final program: 1: NOTHING (2) 2: END (0) minlen 0 Guessing start of match in sv for REx "DBIC" against "DBIC" Found anchored substr "DBIC" at offset 0... Guessed: match at offset 0 Guessing start of match in sv for REx "DBIC" against "DBIC" Found anchored substr "DBIC" at offset 0... Guessed: match at offset 0 A B C Guessing start of match in sv for REx "DANCER" against "DANCER" Found anchored substr "DANCER" at offset 0... Guessed: match at offset 0 Guessing start of match in sv for REx "DANCER" against "DANCER" Found anchored substr "DANCER" at offset 0... Guessed: match at offset 0 Freeing REx: "DBIC" Freeing REx: "DANCER" Freeing REx: "" [download]

$ perl -Mre=debug -le " @F = qw( a b c DBIC A B C DANCER a b c ); prin +t for grep { /DBIC/.. /DANCER/ and ! // } @F; " Compiling REx "DBIC" Final program: 1: EXACT <DBIC> (3) 3: END (0) anchored "DBIC" at 0 (checking anchored isall) minlen 4 Compiling REx "DANCER" Final program: 1: EXACT <DANCER> (4) 4: END (0) anchored "DANCER" at 0 (checking anchored isall) minlen 6 Compiling REx "" Final program: 1: NOTHING (2) 2: END (0) minlen 0 Guessing start of match in sv for REx "DBIC" against "DBIC" Found anchored substr "DBIC" at offset 0... Guessed: match at offset 0 Guessing start of match in sv for REx "DBIC" against "DBIC" Found anchored substr "DBIC" at offset 0... Guessed: match at offset 0 Matching REx "" against "A" 0 <> <A> | 1:NOTHING(2) 0 <> <A> | 2:END(0) Match successful! Matching REx "" against "B" 0 <> <B> | 1:NOTHING(2) 0 <> <B> | 2:END(0) Match successful! Matching REx "" against "C" 0 <> <C> | 1:NOTHING(2) 0 <> <C> | 2:END(0) Match successful! Guessing start of match in sv for REx "DANCER" against "DANCER" Found anchored substr "DANCER" at offset 0... Guessed: match at offset 0 Guessing start of match in sv for REx "DANCER" against "DANCER" Found anchored substr "DANCER" at offset 0... Guessed: match at offset 0 Freeing REx: "DBIC" Freeing REx: "DANCER" Freeing REx: "" [download]