[jira] [Closed] (MCOMPILER-242) Add option to force consistent ordering of source files

["Elliotte Rusty Harold (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MCOMPILER-242?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Elliotte Rusty Harold closed MCOMPILER-242.
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> Add option to force consistent ordering of source files
> -------------------------------------------------------
>
>                 Key: MCOMPILER-242
>                 URL: https://issues.apache.org/jira/browse/MCOMPILER-242
>             Project: Maven Compiler Plugin
>          Issue Type: New Feature
>    Affects Versions: 3.3
>            Reporter: Richard DiCroce
>            Priority: Major
>
> In theory, the order in which source files are compiled should not matter. In practice, there are issues like [JDK-8067422|https://bugs.openjdk.java.net/browse/JDK-8067422] in which compilation order does matter. That issue does not affect the functionality of the compiled class, but does result in different output. This is a problem if you need to create a strictly reproducible build, by which I mean it should be possible to repeat a build and have the checksum for all files be identical.
> Adding such an option would require changes in both maven-compiler-plugin and plexus-compiler-api. Specifically, the method org.codehaus.plexus.compiler.AbstractCompiler#getSourceFiles(CompilerConfiguration) needs to have a check added at the end. Depending on the value of some option in the configuration, it should sort the result array to ensure consistent ordering. The ability to set that option would then be exposed by maven-compiler-plugin.
> I have hacked in such an option without changing maven-compiler-plugin (for simplicity) [here|https://github.com/rdicroce/plexus-compiler/tree/sort-source-files], but it would be nicer if the option were properly exposed. The choice of "-XDsortFiles" comes from the very undocumented javac option of the same name, which is supposed to do the same thing but appears to only have an effect if javac itself needs to walk the directory tree to discover source files.
> Note that, without this change, compilation order is still consistent as long as the files have the same absolute path every time they are compiled. So, for example, if you check out a project and compile it multiple times from "C:/sources/foo", the output will always be the same. But if you check out the project into "C:/other-sources/foo", the order will be different.



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