[bug-gawk] syntax error when setting RS via string concatenation

[Ed Morton]

I didn't expect to get this syntax error when setting RS via string 
concatenation:

    $ awk 'BEGIN{RS="[x"; RS=RS"]"}'
    awk: cmd. line:1: fatal: Unmatched [, [^, [:, [., or [=: /[x/

as opposed to setting it to a variable constructed by the same string 
concatenation

    $ awk 'BEGIN{t="[x"; t=t"]"; RS=t}'
    $

Is that a bug or a feature (and if so, what feature?).

This was in bash on cygwin with:

    $ awk --version
    GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.3, GNU MP 6.0.0)

Regards,

    Ed.