Valid characters for function names

[Reuti]

Hi,

I got a script using foo++() as function name, and at first I was  
confused of a different behavior between bash 4.2, 4.4 and 5.0. After  
crawling some mailing lists whether this is allowed at all, I found  
this post:

first)

https://lists.gnu.org/archive/html/help-bash/2018-12/msg00067.html

Obviously the behavior regarding such a constructed name in 4.2 and  
4.4 was not always coherent. And a plus sign is one of the additional  
characters which Bash allows as an extension.

Nevertheless, also the version 5.0 has in its man-page the passage:

a)
       name   A word consisting only of alphanumeric characters and  
underscores, and beginning with an alphabetic  character  or
              an underscore.  Also referred to as an identifier.

b)
       name () compound-command [redirection]
       function name [()] compound-command [redirection]

Shouldn't this be extended in the man-page to list all valid  
characters? I even wonder where the original poster got the list from.

===

second)

bash-5.0$ foo() { echo Yes; }
bash-5.0$ foo
Yes
bash-5.0$ unset foo
bash-5.0$ foo
bash: foo: command not found

bash-5.0$ baz++() { echo Yes; }
bash-5.0$ baz++
Yes
bash-5.0$ unset baz++
bash: unset: `baz++': not a valid identifier
bash-5.0$ unset -f baz++

Hence there is a rule: if special characters are used inside a  
function name, the the option -f must be used.

Maybe this is related to the fact, that `unset` works for both:  
variables and (and afterwards) for left functions with this name.  
Would it be sensible to jump inside `unset` to scan for a function  
name, once an illegal name for a variable was found? – Or make the use  
of "-f" always mandatory for functions?

-- Reuti