[akasakariko]

AI-assisted implementation and PR description

Summary

• Restore the pre-error GC protection state after a direct compiler error caught by opcache_compile_file()
• Preserve protection for runtime fatals, errors that unwind user callbacks and an already protected collector
• Keep the existing diagnostics, false return value and preload failure behavior

Implementation

Record the fatal error type, execution frame and GC protection through a thread-local error observer before bailout clears the execution frame

Restore protection only for E_COMPILE_ERROR from the current opcache_compile_file() frame and when no OOM has occurred

The observer avoids relying on last_error_type, which can remain stale when repeated errors are suppressed, including when a later runtime fatal has the same message

Verification

• Reproduced on unmodified revision 7c0b9008963e0fbffd4d71f92e01e2ac2b8ec410, GC becomes protected and collects zero cycles after the reported failure
• The same reproduction after the fix keeps GC unprotected and collects 99999 cycles
• Add five PHPT tests covering manual and automatic GC, uncached compilation, disabled automatic GC, a throwing warning handler, repeated errors, nested fatal compilation and memory exhaustion
• Regression tests pass with debug NTS and ZTS builds in shared-memory, file-cache-only and tracing JIT modes
• Zend, OPcache, zend_test, language and basic suites on macOS ARM64 have no unexpected failures
• NTS results are 6375 passed, 202 skipped and 2 expected failures
• ZTS results are 6371 passed, 206 skipped and 2 expected failures

Fixes #24361