Lower javac release options to the metals JDK version

[zielinsky]

Summary by CodeRabbit

• Bug Fixes

  • Improved handling of Java compiler options when configured versions exceed the running JDK.
  • Unsupported Java versions are now adjusted automatically, with a warning shown once for the highest affected version.
  • Improved warnings when the project JDK and running Metals JDK versions differ.
  • Matching project and runtime JDK versions are now handled correctly.

• Tests

  • Added coverage for Java source, target, and release options across supported and unsupported versions.

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📒 Files selected for processing (2)

• metals/src/main/scala/scala/meta/internal/metals/CompilerConfiguration.scala
• tests/unit/src/test/scala/scala/meta/internal/metals/JavaPcOptionsSuite.scala

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📝 Walkthrough

Walkthrough

CompilerConfiguration clamps unsupported Java compiler release options to the running JDK and centralizes JDK mismatch warnings. JavaPcOptionsSuite tests supported, unsupported, repeated, inline, and path-like option values.

Changes

Java option clamping

Layer / File(s)	Summary
Option filtering and mismatch warnings metals/src/main/scala/scala/meta/internal/metals/CompilerConfiguration.scala, tests/unit/src/test/scala/scala/meta/internal/metals/JavaPcOptionsSuite.scala	Java --source, -target/--target, and --release values above the runtime JDK are replaced with the runtime version. Equal JDK versions are accepted. The highest unsupported version triggers one shared warning. Tests cover flag forms, independent values, older or matching releases, and version-like paths.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: 🟡 Moderate · up to 31eb3

The change lowers javac release options, but supported equals-form options can bypass that clamp, leaving some configurations without the intended JDK-version protection. This bounded correctness risk should be fixed or explicitly accepted before merge.

Suggested reviewers: tgodzik, jchyb

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (2 skipped: 2 unsupported.)
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly summarizes the main change: clamping javac release options to the Metals JDK version.

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Actionable comments posted: 2

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Inline comments:
In
`@metals/src/main/scala/scala/meta/internal/metals/CompilerConfiguration.scala`:
- Around line 643-650: Correct the conditional logic in the JDK version handling
around CompilerConfiguration.warnJdkVersionMismatch: the second branch must
detect when jvmVersion.major is greater than metalsJavaVersion.major, rather
than repeating the reversed lower-version comparison. Preserve the warning
arguments and return behavior for both mismatch directions.
- Around line 688-761: Update javaReleaseVersion and replaceJavaRelease to
recognize long Java flags with inline equals values, including --release=,
--source=, and --target=. Ensure versions above runtimeMajor are parsed and
clamped while preserving the flag’s equals form, and add unit coverage for each
supported option form.

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📥 Commits

Reviewing files that changed from the base of the PR and between 063f328 and cfcad17.

📒 Files selected for processing (2)

• metals/src/main/scala/scala/meta/internal/metals/CompilerConfiguration.scala
• tests/unit/src/test/scala/scala/meta/internal/metals/JavaPcOptionsSuite.scala

Included review availability: Your plan provides up to 8 included reviews per hour; 7 remain after this review.

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