CORE-57 - Surface javac diagnostics for runtime compile failures

[sam-ross]

CORE-57 - Surface javac diagnostics for runtime compile failures

Summary

Surfaces javac diagnostics directly when runtime compilation fails, instead of masking the real compile failure as a generated-class ClassNotFoundException.

Context

CachedCompiler.compileFromJava(...) returns an empty map when javac fails. Previously, CachedCompiler.loadFromJava(...) did not distinguish that failure from a successful compile with no classes to define, and still called classLoader.loadClass(className).

With module-style classloaders, this can produce a misleading ClassNotFoundException for the generated class name, hiding the actual javac diagnostics such as missing symbols or unresolved types.

Changes

• Added an internal CompilationResult path in CachedCompiler.
• Preserved the existing map-returning compileFromJava(...) behavior.
• Captured javac diagnostics while continuing to write them to the supplied PrintWriter.
• Changed loadFromJava(...) to throw diagnostic ClassNotFoundException immediately when javac compilation fails.
• Added an explicit guard for “compilation succeeded but did not produce the requested class”.
• Returned the cached class after successful defineClass(...) instead of falling through to classLoader.loadClass(...).
• Added regression tests for:
  • successful generated-class loading with a module-like classloader
  • loader-only dependency compile failure surfacing javac diagnostics
  • successful compile output missing the requested class

Verification

mvn -q -Dtest=CachedCompilerModuleClassLoaderReproTest test
mvn -q -Dtest=CachedCompilerModuleClassLoaderReproTest,CompilerTest,CachedCompilerAdditionalTest test
mvn -q test

[KealanTolandChronicle]

Overall looks good, just one small comment about thread safety string appending, approved!

[benbonavia]

Please reduce the complexity as per the sonar analysis

[sam-ross]

Hi @benbonavia, this is ready for re-review.

I’ve refactored the method Sonar flagged at loadFromJava(...). The cache lookup, file-manager lookup, compile-result validation, class definition loop, class-file writing, and final lookup are now split into private helpers. The public method is now a short orchestration path, while preserving the existing synchronisation and duplicate-definition guard behaviour.

[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud