RFR: 8316648: jrt-fs.jar classes not reproducible between standard and bootcycle builds

[Erik Joelsson]

On Fri, 22 Sep 2023 12:38:03 GMT, Andrew Leonard <aleonard at openjdk.org> wrote:

> jrt-fs.jar classes are currently compiled with the BootJDK being used, this has a couple of issues:
> - The classes are not reproducible between a standard and bootcycle build image, since the first is compiled by jdk-N-1 and the later jdk-N
> - The jrt-fs classes in a standard product image are compiled by the BootJDK (typically jdk-N-1), which means from a "secure dev" perspective they are not compiled with the latest and greatest compiler with all the latest vulnerability fixes. 
> 
> The jrt-fs classes are required to be built targeting jdk-8 compatible, there is no reason they cannot be compiled with the jdk-N "interim" compiler as part of the standard build.
> This then makes the jrt-fs classes reproducible regardless of which bootjdk is used.

Marked as reviewed by erikj (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/15888#pullrequestreview-1639891273