Release Summary

This release focuses on improving developer tooling and stability. Key highlights include significant enhancements to the REPL (YAML configuration support and parse-only evaluation), the addition of cost estimation for regex operations, and improved test coverage reporting.

On the stability front, this release addresses race conditions in reference types, improves namespace resolution, and ensures formatting directives align strictly with the CEL specification.

Note: This release includes a breaking change regarding how types are handled as variables. Please review the "Breaking Changes" section below.

⚠ Breaking Changes

Remove types as variables: The logic for handling types has been relaxed to support safe rollout of feature packages which introduce new types whose names may collide with existing variables. Please review your policies if you relied on types behaving strictly as variables in previous versions. PR #1262

Features & Enhancements

REPL & Tooling

• YAML Configuration: The REPL now supports reading and writing YAML environment configurations. PR #1250

• Parse-Only Mode: Added parse-only evaluation capabilities to the REPL. PR #1254

• Test Coverage: Introduced logic for CEL test coverage calculation and updated the reporter to handle error/unknown scenarios.PR #1209 & PR #1215

Core Library

• Regex Costing: Added support for cost estimation and tracking within the regex library. PR #1200

• JSON Type Exposure: Exposed CEL JSON types to assist developers in converting to native values. PR #1261

• Policy Composition: Source information is now preserved during CEL policy composition, aiding in debugging. PR #1253

Extensibility:

• Updated extension option factory to resolve by ID (#1249).

• Refactored match output compiling to accept user-defined logic (#1246).

• Exposed Match source ID to callers (#1227).

Build & Maintenance

• Bazel: Migrated to use Bazel module only and improved configuration for dependent builds. PR #1231 & PR #1228

• Cleanup: Removed strcase dependency, removed AppEngine code from REPL, and performed general linting. PR #1230, #1216, #1251

Bug Fixes

• Concurrency: Fixed a race condition in the checker regarding reference types. PR #1224

• Namespace Resolution: Addressed an issue with namespace resolution. PR #1256

• Spec Compliance: Fixed formatting directives to fully support requirements documented in the cel-spec. PR #1232

New Contributors

• @catalinadurbala made their first contribution in https://github.com/google/cel-go/pull/1227
• @abenea made their first contribution in https://github.com/google/cel-go/pull/1258

Full Changelog: https://github.com/google/cel-go/compare/v0.26.1...v0.27.0