Unhandled errors in compilation of syntactically defective forms

[Paul F. Dietz]

Stas Boukarev told me on #sbcl that compiling lisp code should never produce unhandled errors. The mutation tester I had been running had been trapping and ignoring general errors, but after that comment I've modified it to report those as well. There are lots of failures. Here are a few

(compile nil '(lambda () . 1)) ==> type error

(compile nil '(lambda () (count 0 '(1 . 2) :test 'eql))) ==> type error

(compile nil '(lambda () (let ((v1 1) . v2) v1))) ==> type-error

Basically, any place in the compiler where a form is being handled by ordinary lisp functions, the case of the list not being a proper list could cause an error to be signaled. In the COUNT example there a list argument to COUNT is malformed, not a lisp form itself.

I can generate an almost unlimited number of tickets for this, but I've given three examples to get it started.