Problem with sequences with variables?

[Tom (AST) Watson]

Hi...

I was trying to do some sequences, and it looks like they don't like variables. 
 See the following:
[user@box3 ~]$ echo $BASH_VERSION
5.0.17(1)-release
[user@box3 ~]$ echo {1..10}
1 2 3 4 5 6 7 8 9 10
[user@box3 ~]$ echo $l
10
[user@box3 ~]$ echo {1..${l}}
{1..10}
[user@box3 ~]$

Shouldn't the second sequence echo be the same as the first sequence echo?  It 
would be MUCH more useful if it were.

Of course, this could be just a feature, I don't really know.  This is running 
on a Fedora 31 release build if that makes a difference.

Thanks,
...Tom Watson

More info:
Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -O2 -g -pipe -Wall -Werror=format-security 
-Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions 
-fstack-protector-strong -grecord-gcc-switches 
-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 
-specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic 
-fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection 
-Wno-parentheses -Wno-format-security
uname output: Linux box3.appsig.com 5.7.7-100.fc31.x86_64 #1 SMP Wed Jul 1 
20:37:05 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-redhat-linux-gnu

Bash Version: 5.0
Patch Level: 17
Release Status: release

--
Tom Watson              (I'm at work now)
Thomas.3.watson@rtx.com