It's possible to leak a ref outside of a let block in tests

[TimDeve]

Running this code gives an address-sanitizer warning in clang as we're letting a reference leak out of it's scope (the string the ref point to is deleted when the let scope is exited)

(Debug.sanitize-addresses)

(load "Test.carp")

(use Test)

(deftest test
  (assert-equal test
    "Wow"
    (let [s @"Wow"]
      &s)
    "Shouldn't compile"))

Doing the same outside a test does give the proper error

(defn main []
  (IO.println (let [s @"Wow"]
                &s)))

The reference '(let [s (String.copy "Wow")] (ref s))' (depending on the variable 's') isn't alive

[eriksvedang]

Good find! We should look at the macro expansion of the test to see more what's up.

[leblowl]

It looks like it expands to:

  (defn main []
    (let [test (ref (Test.State.init 0 0))]
      (do (set! test
                (ref (Test.assert-equal__String*_String
                      test
                      "Wow"
                      (let [s (String.copy "Wow")]
                        (ref s))
                      "Shouldn't compile")))
          (Test.print-test-results test)
          (Int.copy (Test.State.failed test)))))

After tracing things, it seems like (ref s) and test receive the same lifetime variable after unification and so the memory management doesn't think (ref s) is a dead reference when the inner let returns. It looks like it might be the same issue described in #1317 and #470.

[eriksvedang]

Thanks for investigating! And yes, that sounds right.