a bug or a feature?

[Boguslaw Jackowski]

Dear colleagues,

We've encountered a strange behaviour of gawk which has something
to do with the `delete' operator. The following three-liner

  BEGIN {a(); b(S)}
  function a() {delete S}
  function b(s) {s[0]}

reports an error:
  ... fatal: delete: illegal use of variable `S' as array

This error is reported under both Linux and Windows since the
version (at least) 3.1.0 (also in 3.1.2).

Apparently, gawk presumes that `S' should be a scalar judging from
the statement `b(S)'. There is a simple circumvention---it suffices
to add, e.g., a dummy function definition at the beginning of the script:

  function c() {S[0]}

Because of the weirdness of the circumvention, we doubt whether
this behaviour can be considered a `feature'.

Looking forward to hearing from you --

yours sincerely, Bogus\l{}aw Jackowski, Piotr Strzelczyk

Ps. Due to the optimization efforts in most recent versions
    of gawk, the error is reported also for a `traditional'
    form of using the `delete' operator:

    function a() {for (i in S) delete S[i]}

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 Bogus\l{}aw Jackowski: address@hidden
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