What's the equivalent of `boundp' for lexical variables?

[Alan Mackenzie]

Hello, Emacs.

I have a problem in a macro, where I have the expression ,expr.  I want
to evaluate it, but get the error message void-variable (expr).

In the good old days, I could have tested this with

    (if (boundp 'expr) (eval ,expr))

, but now, with lexical variables, I can't find the equivalent to boundp.
Is there such a facility for lexical variables, and if so what is it?

Thanks!

-- 
Alan Mackenzie (Nuremberg, Germany).