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Incorrect bytecode generated for static methods on interfaces

Description

Calls to static interface methods compile on Java 8 but not on Java 9 because of a new bytecode restriction. As the usage of static interface methods increases, this problem will manifest more. I ran into it while using the AWS SDK (2.0 preview) which makes extensive usage of these methods.

public interface JDK8InterfaceMethods { // cannot call either of these from Clojure on Java 9 // throws IncompatibleClassChangeError per JVMS public static long staticMethod0(long v) { return v; } public static String staticMethod1(String s) { return s; } }

The original ticket had a repro here: https://github.com/ztellman/java9-failure

Cause: The JVM spec mandates that invocations to static interface methods refer to an InterfaceMethodref entry in the constant pool rather than simply to a Methodref. See https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-5.html#jvms-5.4.3.3, describing the resolution rules for Methodrefs:

When resolving a method reference: If C is an interface, method resolution throws an IncompatibleClassChangeError.

Bytecode verification was tightened in Java 9 to check for this: https://bugs.openjdk.java.net/browse/JDK-8145148

ASM 5.1+ provide support for this.

Approach: First, upgrade to min Java 8 and latest ASM (6.2 right now) - this is now covered in ticket CLJ-2363. The patch here assumes CLJ-2363 has been completed as a baseline. The change here calls the newer ASM method to gen a static method call with awareness of static interface methods.

Patch: clj-2284-4.patch

Environment

JDK 9 or higher

Attachments

14
  • 25 Jun 2018, 05:45 PM
  • 11 Jun 2018, 03:21 AM
  • 11 Jun 2018, 03:21 AM
  • 11 Jun 2018, 03:21 AM
  • 11 Jun 2018, 03:21 AM
  • 11 Jun 2018, 03:21 AM
  • 17 Feb 2018, 09:57 PM
  • 17 Feb 2018, 09:57 PM
  • 17 Feb 2018, 09:57 PM
  • 17 Feb 2018, 09:57 PM
  • 17 Feb 2018, 09:57 PM
  • 24 Dec 2017, 06:31 PM

Activity

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Alex Miller June 25, 2018 at 5:45 PM

Squashed remaining patches (others in CLJ-2363) and screened.

Alex Miller June 22, 2018 at 3:18 PM

Marking as incomplete pending dependent on pulling the jdk 8 stuff out into CLJ-2363.

Ghadi Shayban June 11, 2018 at 3:21 AM

v3*.patch updates to ASM 6.2 final

Ghadi Shayban March 19, 2018 at 5:23 PM

Workaround macro:

(defmacro interface-static-call [sym & argtypes] `(let [m# (.getMethod ~(symbol (namespace sym)) ~(name sym) (into-array Class ~argtypes))] (fn [& args#] (.invoke m# nil (to-array args#))))) (def client (interface-static-call S3Client/create))

Ghadi Shayban March 19, 2018 at 4:15 PM

The patch in v2-0001 is already based on the ASM-6.1 branch but not the final release. Can bump it with the script in the commit comment.

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Created December 9, 2017 at 10:40 PM
Updated March 3, 2020 at 3:35 PM
Resolved June 27, 2018 at 3:10 PM

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