Dist: dump the base CDS archive when the copied JDK has none (fixes master on macOS x64)

[Frotty]

What

Master's CI fails on macos-15-intel since #1386: assembleSlimCompilerDist throws "The runtime has no base CDS archive". The macOS distribution copies the JDK instead of running jlink, and #1386 assumed the copy brings classes.jsa. The Temurin 25 that setup-java installs on the Intel runner has none (macos-latest, arm64, has one and passed). Run: https://github.com/wurstscript/WurstScript/actions/runs/37778085905 (job Gradle build on macos-15-intel).

• assembleSlimCompilerDist dumps the archive with java -Xshare:dump when the copied runtime has none, so the runtime always has one.
• It then starts the runtime with -Xshare:on, which fails without a usable archive, instead of looking for a file name (a file in the wrong mode passes a name check and does nothing).
• The JVMs it starts run without JAVA_TOOL_OPTIONS, _JAVA_OPTIONS and JDK_JAVA_OPTIONS: an archive takes on the options of the JVM that writes it, and CI exports -XX:+UseCompactObjectHeaders.

Why master broke unnoticed

Pull-request CI runs one Linux job and does not package (Package slim runtime runs on pushes only), so #1386 was never packaged on macOS before it merged. To test this change where it matters I ran a temporary workflow in this pull request (packaging on macos-15-intel, macos-latest and Windows with CI's JAVA_TOOL_OPTIONS; run 37783008340, since removed). Whether packaging should run on pull requests which touch deploy.gradle or launchers/ is a call for the maintainers.

Checks

macOS and Windows, on CI (the temporary workflow, with CI's JAVA_TOOL_OPTIONS; packageSlimCompilerDist succeeded on all three):

• macos-15-intel: the JDK's lib/server holds only libjsig.dylib and libjvm.dylib (Temurin 25.0.4+101.0). The distribution has a 15.6 MB classes.jsa after the build, and java -Xshare:on -version (without JAVA_TOOL_OPTIONS) starts with "sharing".
• macos-latest (arm64) and windows-latest: pass.

Windows, local:

• assembleSlimCompilerDist builds; bin/server has classes.jsa.
• With the archive deleted from the jlink image and -x jlinkRuntime25 (the full-JDK case): "The runtime has no base CDS archive, dumping it", the guard passes.
• With CI's JAVA_TOOL_OPTIONS set the archive is still the default-mode classes.jsa (not classes_coh.jsa).
• A second run reuses the configuration cache entry and executes the new code.

Not run: Linux packaging (unchanged path: jlink makes the archive; master's push run for #1386 passed on ubuntu-latest).

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-08T13:23:30.864713Z	8cbec3a	Manual request

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.

[Frotty]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Keep them coming!

Reviewed commit: 8cbec3a41b

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".