[jboss-jira] [JBoss JIRA] (DROOLS-2814) MVEL uses random parameter type methods for BigDecimal.valueOf(100)

[Toshiya Kobayashi (JIRA)]

    [ https://issues.jboss.org/browse/DROOLS-2814?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13613020#comment-13613020 ] 

Toshiya Kobayashi commented on DROOLS-2814:
-------------------------------------------

Just wanted to mention, this analysis is done by [~mkobayas]. Thanks!

> MVEL uses random parameter type methods for BigDecimal.valueOf(100)
> -------------------------------------------------------------------
>
>                 Key: DROOLS-2814
>                 URL: https://issues.jboss.org/browse/DROOLS-2814
>             Project: Drools
>          Issue Type: Bug
>          Components: core engine
>    Affects Versions: 7.9.0.Final
>         Environment: - MVEL2 2.4.0.Final
>            Reporter: Toshiya Kobayashi
>            Assignee: Mario Fusco
>              Labels: support
>         Attachments: BigDecimalMvelTest.zip
>
>
> When MVEL evaluates 
> {noformat}
> java.math.BigDecimal.valueOf(100)
> {noformat}
> , MVEL determines a method from valueOf(double val) or valueOf(long val).
> The result is not consistent. Sometimes uses valueOf(double val), Sometimes uses valueOf(long val).
> ParseTools.getMethodScore() gives the same score for double and long.
> https://github.com/mvel/mvel/blob/master/src/main/java/org/mvel2/util/ParseTools.java#L312-L367
> So a selected method will depend on the order of result of "cls.getMethods()".
> Reproducer:
> $ unzip BigDecimalMvelTest.zip
> $ cd BigDecimalMvelTest
> $ mvn compile
> $ ./loop.sh
> It runs the MVEL test 100 times:
> {noformat}
> $ ./loop.sh 
> result = 100.0
> result = 100.0
> result = 100.0
> result = 100
> result = 100.0
> result = 100.0
> ...
> {noformat}
> In my environment, "100.0" is the majority but randomly see "100" as well. (I couldn't reproduce with single run with java for loop)
> Expectation is constantly "100" (using valueOf(long val)) because in case of usual Java "java.math.BigDecimal.valueOf(100)", Java compiler chooses valueOf(long val) if the parameter is int. (considering "direct supertype" https://docs.oracle.com/javase/specs/jls/se8/html/jls-4.html#jls-4.10)



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