Hello dear monks,

in my latest project I wanted to replace hard coded literals with constants.
In one case there was a simple loop, which used an expression with a constant for the terminal range value.
Here i stumbled upon an unexpected behavior.
Can someone shed some light on what is going on?

Thanks a lot!

This test program

use strict;
use warnings;

sub ten { 10 }

print "9 .. 10 - 1 without constant\n";
for my $i (9 .. 10 - 1) {
  print $i, "\n";
}
print "-> expected\n\n";

print "9 .. 10 - 1 with constant()\n";
for my $i (9 .. ten() - 1) {
  print $i, "\n";
}
print "-> expected\n\n";

print "9 .. 10 - 1 with constant\n";
for my $i (9 .. ten - 1) {
  print $i, "\n";
}
print "-> unexpected\n\n";

print "9 .. 10 with constant\n";
for my $i (9 .. ten) {
  print $i, "\n";
}
print "-> expected\n\n";
[download]

(run with Strawberry Perl 5.26.2) yields:

9 .. 10 - 1 without constant
9
-> expected

9 .. 10 - 1 with constant()
9
-> expected

9 .. 10 - 1 with constant
9
10
-> unexpected

9 .. 10 with constant
9
10
-> expected
[download]

It seems literals cannot simply be replaced by defined constants, which i consider rather unfortunate.