Primitive return type of loop and try is lost

Question

(set! *warn-on-reflection* true)
(fn [] (loop [b 0] (recur (loop [a 1] a))))


Generates the following warnings:


recur arg for primitive local: b is not matching primitive, had: Object, needed: long
Auto-boxing loop arg: b


This is interesting for several reasons.  For one, if the arg to {{recur}} is a {{let}} form, there is no warning:


(fn [] (loop [b 0] (recur (let [a 1] a))))


Also, the compiler appears to understand the return type of {{loop}} forms just fine:


(use '[clojure.contrib.repl-utils :only [expression-info]])
(expression-info '(loop [a 1] a))
;=> {:class long, :primitive? true}


The problem can of course be worked around using an explicit cast on the {{loop}} form:


(fn [] (loop [b 0] (recur (long (loop [a 1] a)))))


Reported by leafw in IRC: http://clojure-log.n01se.net/date/2011-01-03.html#10:31

*See Also:* CLJ-1422

*Patch:* 0001-CLJ-701-add-HoistedMethod-to-the-compiler-for-hoisti-v2.patch

Answer 1

Comment made by: hiredman

so I don't forget, I realized the issue with data.xml is because the 'is' macro in the test expands in to a try/catch in an expression context, which is hoisted, and the hoist causes the whole environment not to be cleared until the hoisted method returns, which is obviously not correct.

Answer 2

Reference: https://clojure.atlassian.net/browse/CLJ-701 (reported by chouser@n01se.net)