Re: bin/52623: nonsense error message in awk

[David Holland <dholland-bugs%netbsd.org@localhost>]

The following reply was made to PR bin/52623; it has been noted by GNATS.

From: David Holland <dholland-bugs%netbsd.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: bin/52623: nonsense error message in awk
Date: Mon, 16 Oct 2017 17:28:30 +0000

 On Mon, Oct 16, 2017 at 07:20:01AM +0000, Robert Elz wrote:
  >>  awk -F: < /etc/passwd '{ a[$1] = $3; } END { for (k in a) print k[a]; }'
  >  
  >  When that is compiled, awk can see from the reference to k[a] that k is
  >  an array.   The syntax is all OK, so the compile succeeds.
 
 It's doing type inference?
 
  >  When it is executed, and we get to the "for (k in a)" we need to assign
  >  the indexes of array a to k, which can't be done, as k is an array.
  >  
  >  Hence:
  >>    awk: can't assign to k; it's an array name.
  >  
  >  What would you have it do differently?
 
 I would expect it to, on the first iteration, assign k to the first
 value in a[], then choke at the print where it tries to use an array
 to index an array expression and/or tries to index an array as a
 scalar.
 
 e.g.
 
    awk: can't read value of a; it's an array name.
 
 -- 
 David A. Holland
 dholland%netbsd.org@localhost