haukex:

Hmmm ... I just played around with it using Devel::Peek to see what the values in the sequence are:

#!env perl
use strict;
use warnings;
use Devel::Peek;
use Data::Dump 'pp';
use v5.20;

say qq{"8" .. "C" generates strings "8" .. "9"};
dump_seq("8" .. "C");

say qq{"8" .. "9" generates integers 8 .. 9};
dump_seq("8" .. "9");

say qq{"-1" .. "2" generates integers -1 .. 2};
dump_seq("-1" .. "2");

say qq{"B" .. "C" generates strings "B" .. "C"};
dump_seq("B" .. "C");

say qq{"9" .. "7" generates nothing};
dump_seq("9" .. "7");

say qq{"C" to "A" generates strings "C" .. "Z"};
dump_seq("C" .. "A");

sub dump_seq { Dump($_) for @_; print "---\n\n"; }
[download]

Running it gives (edited for brevity):

$ perl pm_1226451.pm
"8" .. "C" generates strings "8" .. "9"
SV = PV(0x600004240) at 0x600003680
  REFCNT = 2
  FLAGS = (POK,pPOK)
  PV = 0x600069f20 "8"\0
  CUR = 1
  LEN = 10
SV = PV(0x600004260) at 0x600003758
  REFCNT = 2
  FLAGS = (POK,pPOK)
  PV = 0x600172e00 "9"\0
  CUR = 1
  LEN = 10
---

"8" .. "9" generates integers 8 .. 9
SV = IV(0x600003670) at 0x600003680
  REFCNT = 2
  FLAGS = (IOK,pIOK)
  IV = 8
SV = IV(0x600003748) at 0x600003758
  REFCNT = 2
  FLAGS = (IOK,pIOK)
  IV = 9
---

"-1" .. "2" generates integers -1 .. 2
SV = IV(0x600003670) at 0x600003680
  REFCNT = 2
  FLAGS = (IOK,pIOK)
  IV = -1
SV = IV(0x600003748) at 0x600003758
  REFCNT = 2
  FLAGS = (IOK,pIOK)
  IV = 0
SV = IV(0x600003760) at 0x600003770
  REFCNT = 2
  FLAGS = (IOK,pIOK)
  IV = 1
SV = IV(0x600003898) at 0x6000038a8
  REFCNT = 2
  FLAGS = (IOK,pIOK)
  IV = 2
---

"B" .. "C" generates strings "B" .. "C"
SV = PV(0x600004240) at 0x600003680
  REFCNT = 2
  FLAGS = (POK,pPOK)
  PV = 0x6001b5be0 "B"\0
  CUR = 1
  LEN = 10
SV = PV(0x600004260) at 0x600003758
  REFCNT = 2
  FLAGS = (POK,pPOK)
  PV = 0x600069f20 "C"\0
  CUR = 1
  LEN = 10
---

"9" .. "7" generates nothing
---

"C" to "A" generates strings "C" .. "Z"
SV = PV(0x600004240) at 0x600003680
  REFCNT = 2
  FLAGS = (POK,pPOK)
  PV = 0x6001b5be0 "C"\0
  CUR = 1
  LEN = 10
SV = PV(0x600004260) at 0x600003758
  REFCNT = 2
  FLAGS = (POK,pPOK)
  PV = 0x600069f20 "D"\0
  CUR = 1
  LEN = 10

    <<< SNIP SNIP SNIP >>>

SV = PV(0x6001a99f0) at 0x6001a4160
  REFCNT = 2
  FLAGS = (POK,pPOK)
  PV = 0x600196010 "Z"\0
  CUR = 1
  LEN = 10
---
[download]

It appears that when both values appear to be integers, it terminates the loop before generating any values if the second value is less than the first. For strings, it appears to just keep on going, terminating when it hits "the last letter". I wonder how it interacts with the locale for non-ASCII/English character sets. (Not motivated, however, to do the experiments myself, nor knowledgeable enough about Unicode and non-English character sets to be sure I could do the experiments well had I wanted to.)

...roboticus

When your only tool is a hammer, all problems look like your thumb.

I just played around with it using Devel::Peek to see what the values in the sequence are

Good idea - and checking with Devel::Peek::Dump() shows up another anomaly:

C:\_32>perl -MDevel::Peek -le "@x=('0' .. '2'); Dump $x[0];"
SV = PV(0x54c658) at 0x54bc28
  REFCNT = 1
  FLAGS = (POK,pPOK)
  PV = 0x548438 "0"\0
  CUR = 1
  LEN = 10

C:\_32>perl -MDevel::Peek -le "@x=('1' .. '2'); Dump $x[0];"
SV = IV(0x31bc18) at 0x31bc28
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 1
[download]

It appears that something being done by the range operator changes the PV '1' to an IV, but leaves the string '0' as a PV.
I wouldn't be surprised if this different treatment is causally related to the unexpected behaviour being exhibited.

Cheers,
Rob

Thanks for looking into this, syphilis, roboticus, and rsFalse! dave_the_m replied to the bug, and I just posted a reply there.