Fix custom CAST rules with expressions, fix #322.

In a previous commit the typemod matching code had been broken, and we
failed to notice that until now. Thanks to bug report #322 we just got
the memo...

Add a test case in the local-only MySQL database.

The regression testing facilities should be improved to be able to test
a full database, and then to dynamically create said database from code
or something to ease test coverage of those cases.

src/sources/common/casting-rules.lisp

@@ -27,7 +27,7 @@
 	    (mapcar #'parse-integer
 		    (sq:split-sequence #\, column-type
 				       :start (+ 1 start-1) :end end))
-	  (cons a b))))))
+	  (list a b))))))
 
 (defun typemod-expr-matches-p (rule-typemod-expr typemod)
   "Check if an expression such as (< 10) matches given typemod."
@@ -98,7 +98,7 @@
 		   (t type)))
 		(pg-typemod
 		 (when source-typemod
-		   (destructuring-bind (a . b) source-typemod
+		   (destructuring-bind (a &optional b) source-typemod
 		     (format nil "(~a~:[~*~;,~a~])" a b b)))))
             (make-column :name (apply-identifier-case source-column-name)
                          :type-name type-name

test/parse/hans.goeuro.load

@@ -26,8 +26,9 @@ LOAD DATABASE
       column ascii.s using byte-vector-to-bytea,
       column enumerate.foo using empty-string-to-null,
 
-      column ip.ip_address to inet keep not null drop typemod
+      column ip.ip_address to inet keep not null drop typemod,
 
+      type decimal when (= precision 1) to boolean drop typemod
 
  MATERIALIZE VIEWS nonexisting,
    d as $$