bug#25292: Ambiguity in doc string of defvar

[Alan Mackenzie]

Hello, Emacs.

The doc string for defvar includes this bit:

    The optional argument INITVALUE is evaluated, and used to set
    SYMBOL, only if SYMBOL's value is void.

Supposing SYMBOL's value is bound.  Clearly it does not get set to
INITVALUE.  But in this case is INITVALUE evaluated (and the result
discarded) or not?  The text leaves this ambiguous.  An improvement
would be the appropriate one of the following:

    If SYMBOL's value is void, the optional argument INITVALUE is
    evaluated and used to set SYMBOL.

    INITVALUE is evaluated, and if SYMBOL's value is void, it is used to
    set SYMBOL.

-- 
Alan Mackenzie (Nuremberg, Germany).