[jira] [Commented] (BCEL-323) JDK 13 build failing in master: BCELifierTestCase.testJavapCompare

["Tomo Suzuki (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/BCEL-323?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16882401#comment-16882401 ] 

Tomo Suzuki commented on BCEL-323:
----------------------------------

[~ggregory] Thank you.

> JDK 13 build failing in master: BCELifierTestCase.testJavapCompare
> ------------------------------------------------------------------
>
>                 Key: BCEL-323
>                 URL: https://issues.apache.org/jira/browse/BCEL-323
>             Project: Commons BCEL
>          Issue Type: Improvement
>            Reporter: Tomo Suzuki
>            Priority: Minor
>             Fix For: 6.4.0
>
>         Attachments: screenshot-1.png, screenshot-2.png
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> h1. Problem
> With OpenJDK 13 EA, BCELifer does not give "default" modifier for an [interface's default method|https://docs.oracle.com/javase/tutorial/java/IandI/defaultmethods.html].
> [https://travis-ci.org/apache/commons-bcel/jobs/556441835]
> {code:java}
> [INFO] 
> [INFO] Results:
> [INFO] 
> [ERROR] Failures: 
> [ERROR]   BCELifierTestCase.testJavapCompare:90->testClassOnPath:80 expected:<...a8Example {
>  public [default ]void hello();
>  Code:...> but was:<...a8Example {
>  public []void hello();
>  Code:...>
> [INFO] 
> [ERROR] Tests run: 130, Failures: 1, Errors: 0, Skipped: 1{code}
>  
> I'm checking why it fails.
> Memo for myself:
> {code:java}
> export JAVA_HOME=${HOME}/local/jdk-13
> export PATH=${JAVA_HOME}/bin:$PATH{code}
> h1. Difference causing Test Failure
> In OpenJDK 13, the default parameter for the interface disappears after BCELifier creates the class file.
> !screenshot-1.png! 
>   
> {code:java}
> $ java -version
> openjdk version "13-ea" 2019-09-17
> OpenJDK Runtime Environment (build 13-ea+28)
> OpenJDK 64-Bit Server VM (build 13-ea+28, mixed mode, sharing){code}
> h2. What does BCELifierTestCase do?
> The test compares two output of javap command:
>  * javap "target/test-classes/Java8Example.class" (which is copied from ./src/test/resources/Java8Example.class in git)
>  * javap another Java8Example.class which is generated by BCELifer.
>  ** Actually the class file is not directly created by BCELifer.
>  *** BCELifer writes Java8ExampleCreator.java
>  *** The test runs "javac" to compile Java8ExampleCreator.
>  *** The test runs "java" to run Java8ExampleCreator, which in turn generates Java8Example.class
> JDK 13's javap command adds "default" for the first Java8Example.class but not on the second one.
> h2. Question to Answer
> Q. In theory, because Java8Example.class is generated by BCEL, not JDK, the output should not change. Which part of BCEL relies on JDK?
> A. This question is irrelevant, because the output class files are all the same (see below).
> Q. Is there difference between Java8ExampleCreator.java files from JDK 8 and JDK 13?
> A. They are the same.
> Q. How to see the difference between Java8Example.class from JDK 8 and JDK 13?
> * javap (screenshot shown above)
>  !screenshot-2.png! 
> * binary diff editor?
> Q. What about JDK 11?
> A. JDK 11's javap does not show "default" for both Java8Example.class files. JDK11's generated Java8Example.class has 1 attributes. The resulting Java8Example.class files are all the same across JDKs:
> {code}
> $ md5sum /tmp/target-jdk*/Java8Example.class
> f4c51ee3d4864cb226e79cfca8dbe6da  /tmp/target-jdk11/Java8Example.class
> f4c51ee3d4864cb226e79cfca8dbe6da  /tmp/target-jdk13/Java8Example.class
> f4c51ee3d4864cb226e79cfca8dbe6da  /tmp/target-jdk8/Java8Example.class{code}
> So it's the matter of javap command showing "default" or not.
> Q. JDK 13's javap outputs "default" under certain condition. What is the condition?
> A. It's when major.minor >= 52.0, as per http://hg.openjdk.java.net/jdk/jdk13/rev/77b54b2822cc
> h1. Root Cause
> Open JDK 13's javap shows "default" when major.minor >= 52.0 ([commit in June 2019|http://hg.openjdk.java.net/jdk/jdk13/rev/77b54b2822cc]). BCEL while BCELifier was not copying major.minor (default: "45.3").



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