redefining a function does not produce an error, but does not work

[David Jeske]

(include "lib/basis.scm")
(define (a x) (+ x 1))
(define (a x) (+ x 10))
(a 10)  ;; today yields 11

I expect this either to yield 20, or to be a compile error.

[Sam Rushing]

checked with your repro:

$ self/compile tests/t_jeske1.scm
read...
transform...

duplicate name:
***
Runtime Error, halting: a

The exception that is raised carries both symbols. If/when symbols carry file/pos info, the error message will be better.