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`proxy` fails with redefined interfaces

Description

Before patch:

user=> (definterface I (f [])) user.I user=> (def p (proxy [Object I] [] (f [] 1))) #'user/p user=> (definterface I (f [])) user.I user=> (def p (proxy [Object I] [] (f [] 1))) #'user/p user=> (.f ^I p) ClassCastException user.proxy$java.lang.Object$I$383c225e cannot be cast to user.I user$eval7491.invokeStatic (:1)

After patch:

user=> (definterface I (f [])) user.I user=> (def p (proxy [Object I] [] (f [] 1))) #'user/p user=> (definterface I (f [])) user.I user=> (def p (proxy [Object I] [] (f [] 1))) #'user/p user=> (.f ^I p) 1

Cause: `proxy` caches the generated class using a set of classnames (see https://github.com/clojure/clojure/blob/master/src/clj/clojure/core_proxy.clj#L280-L286), this is not safe under redefinition of interfaces

Proposed: change the hashing function used to determine proxy class cache hits to take into account the identity of each interface/super class rather than just their name

Patch: 0001-CLJ-2379-idempotent-proxy-name-just-on-identical-ins-v2.patch

Environment

None

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2
  • 02 Aug 2018, 04:26 PM
  • 02 Aug 2018, 10:49 AM

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Nicola Mometto August 2, 2018 at 4:26 PM

As discussed in #clojure-dev, attached patch that disables the brittle tests and restores the determinism of `proxy-name`.

Alex Miller August 2, 2018 at 11:06 AM

Looks like this breaks the serialized objects in the (admittedly fragile) clojure.test-clojure.java-interop/test-proxy-non-serializable (see CLJ-2204, CLJ-2330).

Nicola Mometto August 2, 2018 at 10:52 AM

sure, done

Alex Miller August 2, 2018 at 10:52 AM

I'm not sure I get the problem/solution here.

Alex Miller August 2, 2018 at 10:50 AM

Can you add a Proposed line to the description explaining the change?

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Created August 2, 2018 at 10:42 AM
Updated September 21, 2021 at 5:36 PM