Clojure resolves to wrong deftype classes when AOT compiling or reloading
Description
Compiling a class via `deftype` during AOT compilation gives different results for the different constructors. These hashes should be identical.
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user=> (binding [*compile-files* true] (eval '(deftype Abc [])))
user.Abc
user=> (hash Abc)
16446700
user=> (hash (class (->Abc)))
31966239 ;; should be 16446700This also means that whenever there's a stale AOT compiled deftype class in the classpath, that class will be used rather then the JIT compiled one, breaking repl interaction.
Another demonstration of this classloader issue (from CLJ-1495) when reloading deftypes (no AOT) :
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user> (defrecord Foo [bar])
user.Foo
user> (= (->Foo 42) #user.Foo{:bar 42}) ;;expect this to evaluate to true
true
user> (defrecord Foo [bar])
user.Foo
user> (= (->Foo 42) #user.Foo{:bar 42}) ;;expect this to evaluate to true also -- but it doesn't!
false
user>This bug also affects AOT compilation of multimethods that dispatch on a class, this affected core.match for years see http://dev.clojure.org/jira/browse/MATCH-86, http://dev.clojure.org/jira/browse/MATCH-98. David had to work-around this issue by using a bunch of protocols instead of multimethods.
Cause of the bug: currently clojure uses Class.forName to resolve a class from a class name, which ignores the class cache from DynamicClassLoader thus reloading deftypes or mixing AOT compilation at the repl with deftypes breaks, resolving to the wrong class.
Approach: the current patch (CLJ-979-v7.patch) addresses this issue in multiple ways:
it makes RT.classForName/classForNameNonLoading look in the class cache before delegating to Class/forName if the current classloader is not a DynamicClassLoader (this incidentally addresses also CLJ-1457)
it makes clojure use RT.classForName/classForNameNonLoading instead of Class/forName
it overrides Classloader/loadClass so that it's class cache aware – this method is used by the jvm to load classes
it changes gen-interface to always emit an in-memory interface along with the [optional] on-disk interface so that the in-memory class is always updated.
Patch: CLJ-979-v7.patch
Screened by: Alex Miller
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