RFR: 8275745: Reproducible copyright headers [v3]

[Emmanuel Bourg]

On Thu, 11 Nov 2021 15:37:09 GMT, Emmanuel Bourg <duke at openjdk.java.net> wrote:

>> The copyright headers are generated at build time, and the year inserted in the template depends on the current date. This means the headers are not reproducible if the project is built a year later. The year in the headers could be derived from the SOURCE_DATE_EPOCH environment variable to make the build reproducible (this variable is already used in other parts of the build).
>
> Emmanuel Bourg has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains two commits:
> 
>  - Make gensrc code use $COPYRIGHT_YEAR
>  - Set COPYRIGHT_YEAR from SOURCE_DATE_EPOCH if present

Thanks again for walking me through the process, I'll try to submit more reproducibility fixes, there are a few more patches pending in Debian:
https://salsa.debian.org/openjdk-team/openjdk/-/blob/openjdk-17/debian/patches/reproducible-build-jmod.diff
https://salsa.debian.org/openjdk-team/openjdk/-/blob/openjdk-17/debian/patches/reproducible-build-user.diff
https://salsa.debian.org/openjdk-team/openjdk/-/blob/openjdk-17/debian/patches/reproducible-character-data.diff
https://salsa.debian.org/openjdk-team/openjdk/-/blob/openjdk-17/debian/patches/reproducible-javadoc-timestamp.diff
https://salsa.debian.org/openjdk-team/openjdk/-/blob/openjdk-17/debian/patches/reproducible-module-info.diff
https://salsa.debian.org/openjdk-team/openjdk/-/blob/openjdk-17/debian/patches/reproducible-properties-timestamp.diff

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PR: https://git.openjdk.java.net/jdk/pull/1498