[bug-gawk] SYMTAB contains future variables

[Joep van Delft]

Hello, 

Please consider the following program: 

    % gawk 'BEGIN{for(s in SYMTAB){print s};a=1}'

I would expect 'a' not to be in the output, as it is at the time of
the for loop, a defined global variable or array. Yet it is.
Neither inserting a sleep call with the system function between the
for-loop and the assignment, nor moving the assignment to an
END{}-block, changes the behavior. 

What _does_ work, is the following trick to hide the variable name
to the interpreter: 

    % gawk 'BEGIN{for(s in SYMTAB){print s};SYMTAB["a"]=1}'

    % gawk --version
    GNU Awk 4.1.1, API: 1.1 (GNU MPFR 3.1.2-p10, GNU MP 6.0.0)
    Copyright (C) 1989, 1991-2014 Free Software Foundation.

Kind regards, 

Joep