Compiling module descriptors is not reproducible? (original) (raw)

Remi Forax forax at univ-mlv.fr
Sat May 19 12:30:21 UTC 2018

----- Mail original -----

De: "Alan Bateman" <Alan.Bateman at oracle.com> À: "org openjdk" <org.openjdk at io7m.com>, "jigsaw-dev" <jigsaw-dev at openjdk.java.net> Envoyé: Samedi 19 Mai 2018 13:26:55 Objet: Re: Compiling module descriptors is not reproducible?

On 19/05/2018 10:18, Mark Raynsford wrote:

Hello!

I've been interested for a while in making all of my software builds reproducible [0]. I don't think there's ever been any kind of written guarantee that the output of javac will be completely deterministic, but to date it seems like it actually has been. However, I was a bit disappointed today to find that the output of one of the builds at AdoptOpenJDK [1] seems to be inserting compiler version information into compiled module descriptors. It doesn't seem to be doing this for any other class files. The requires table in the Module attribute can be used by compilers to record version information about dependences. javac does record the version information, I don't know if there is a way to disable that.

It seems there is no way: http://hg.openjdk.java.net/jdk/jdk/file/5ec7380f671d/src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/ClassWriter.java#l986

In any case, I assume your question will be partly answered by looking at the output of java --list-modules on the different builds. If you download OpenJDK builds from jdk.java.net/10 then you should see that the standard and JDK-specific modules all report their version string as "10" or "10.0.1" as they have been built with configure options that make it so. At a guess, your mail may have included the output from an exploded (as opposed to images) build.

-Alan

Rémi

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