evaluating "&&" order with div by zero in subsequent part.

[Ed Morton]

There's some inconsistency in the following division by zero treatment  
(gawk 5.1.1 on cygwin):

Let's say we have a script that's trying to divide 4 by some number if 
that input value is non-zero:

   $ echo 2 | awk '{ print ($0 && (4/$0)) }'
   1

These all make sense, dividing by that input value:

   $ echo 0 | awk '{ print ($0 && (4/$0)) }'
   0
   $ echo 0 | awk '{ print (0 && (4/$0)) }'
   0
   $ echo 0 | awk '{ print ($0 && (4/($0+0))) }'
   0

but then if we swap denominator $0 which has value 0 with literal 0:

   $ echo 0 | awk '{ print (0 && (4/0)) }'
   awk: cmd. line:1: error: division by zero attempted

and if we then put parens around the numerator 4 and leave the 
denominator 0:

   $ echo 0 | awk '{ print (0 && ((4)/0)) }'
   0

Since the manual at 
https://www.gnu.org/software/gawk/manual/html_node/Boolean-Ops.html says 
(emphasis mine):
> |boolean1 && boolean2|
>
>     True if both boolean1 and boolean2 are true. For example, the
>     following statement prints the current input record if it contains
>     both ‘edu’ and ‘li’:
>
>     if ($0 ~ /edu/ && $0 ~ /li/) print
>
>     *The subexpression **boolean2**is evaluated only if **boolean1**is
>     true. *

I'd have expected that in all cases except the first script above, since 
the first part of the compound condition evaluates to `0 &&` that the 
second part that contains the divide by zero wouldn't be evaluated and 
we'd always print 0. Having said that, I can see that if there's a piece 
of code with a constant 0 as the denominator that it'd be good to get a 
divide by zero error in case that's ever hit as that's obviously a bug, 
but then I'd have expected puting parens around `4` not to change the 
behavior.

Regards,

    Ed.