Re: [Chicken-hackers] [PATCH] two scrutinizer fixes

[Peter Bex]

On Mon, Nov 05, 2012 at 08:15:31PM +0100, Felix wrote:
> a) when matching "list-of"/"vector-of" with "list"/"vector", each
>    element of the latter must match the element-type of the former
>    (reported by megane, fixes #948). Previously the "list"/vector"
>    type was matched as "(list-of (or ...))" instead, which makes
>    the match less precise.

The patch looks like it's the correct way to fix the example.
However, I'm not sure, but doesn't this still go wrong in the case a
list is matched against a pair?

A small change in the test causes the compiler to accept the program
silently; just change (apply1 + (list 'a 2 3)) to
(apply1 + (cons 'a (cons 2 '()))).  AFAIK this is just the same problem:
pairs are converted to a (list-of (or symbol fixnum)).

I tried to fix it first in the case in the same place you changed, but
I think it never gets there due to the clause before it:

(and (pair? t2) (eq? 'pair (car t2))) precedes
(and (pair? t1) (eq? 'list-of (car t1))) so checking for a pair type
on t2 is pointless since it will never match (unless I'm missing
something) due to the former path already having been taken.

I messed around in the code a bit more, but was unable to come up with
an effective patch :(

> b) when matching result-types, allow "undefined" to match "noreturn"
>    as the "noreturn" property can not be inferred for foreign procedures
>    (for example) in general

Shouldn't this only be the case when doing a non-strict type match?
ie, when (not exact) is true?  I admit, I'm still a little unclear on
how exact is supposed to work...

> Additionally, when converting the internal node tree in the compiler
> to expressions, internal type-declaration forms are not shown to
> reduce clutter in the output (this is just a cosmetic change).

Only in debugging mode, when the user has uncommented the define-syntax
that disables the debugging stuff, right?

Cheers,
Peter
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