What's Changed

Breaking Changes 🛠

• Switch compilation from C++17 to C++20. by @fruffy in #4347
• [#5350] Replace underscores with hyphens for diagnostic types in the ErrorCatalog by @kfcripps in #5360

Changes to the Compiler Core

• Loop unrolling fix by @ChrisDodd in #5344
• Fix type unification bug with `int' args by @ChrisDodd in #5346
• Moved warnings about unused instances before the first constant folding by @dmatousek in #5342
• Fix unification of serializable enums by @ChrisDodd in #5348
• Print warnings in a deterministic order by @kfcripps in #5352
• ensure child of IR::SwitchCase remains a BlockStatement by @ChrisDodd in #5349
• Extended Type_InfInt handling in ExpressionEvaluator by @MichalKekely in #5355
• Fixed SIGSEGV crash in struct assign by @MichalKekely in #5356
• Extension to strength reduction for issue 5280 by @ChrisDodd in #5281
• Remove GetV1ModelVersion from front end by @fruffy in #5390
• Support for arrays of extern instances by @ChrisDodd in #5338
• Extend CopyStructures to optionally copy tuples by @ChrisDodd in #5364
• Fix simplifySwitch handling of enums by @ChrisDodd in #5365
• Fix EliminateTuples bug with nested struct/tuples by @ChrisDodd in #5362
• Avoid 'fatal error : Broken pipe' from preprocessor by @ChrisDodd in #5400
• JSON error checking when loading by @ChrisDodd in #5401
• Fix/reorganize to/fromJSON code by @ChrisDodd in #5403

Changes to the Control Plane

• Make building the control-plane (and protobuf) optional. by @fruffy in #5368

Changes to the eBPF Back Ends

• Add support for operations on value with sizes > 64-bit by @vbnogueira in #5345

Changes to the TC Back End

• Make struct used by digest in p4tc packed by @vbnogueira in #5329
• Add Checksum extern support to the TC backend by @vbnogueira in #5357
• Add Random extern support to the TC backend by @vbnogueira in #5354
• Add redirect_l2 test case by @vbnogueira in #5406
• Add p4tc routing testcases by @vbnogueira in #5409

Changes to the P4Tools Back End

• Remove unnecessary table stepper object from pna exr_stepper by @dparker01 in #5366

Changes to the Tofino Back End

• Fix gtestasm (tests now throw CompilerBug rather than aborting) by @ChrisDodd in #5393

Other Changes

• Add back test case for #5333 by @kfcripps in #5351
• Print message when P4TEST_IGNORE_STDERR is used by @chreekat in #5358
• Bump actions/checkout from 4 to 5 by @dependabot[bot] in #5363
• Bump actions/github-script from 7 to 8 by @dependabot[bot] in #5374
• Bump actions/setup-python from 5 to 6 by @dependabot[bot] in #5373
• [docs] Added test guide by @Vineet1101 in #5215
• Add 248 negative tests to p4_16_errors by @KunJeong in #5369
• Small build cleanups by @chreekat in #5388
• Disable ptf-ebpf-kernels-weekly workflow by @chreekat in #5391
• Bump peter-evans/find-comment from 3 to 4 by @dependabot[bot] in #5396
• Bump peter-evans/create-or-update-comment from 4 to 5 by @dependabot[bot] in #5395
• Prevent unintended backtick parsing by @chreekat in #5397
• Increase minimum required BISON version to 3.1 by @kfcripps in #5398
• Bump grpcio for Mac by @chreekat in #5404
• Automated Release v1.2.5.9 by @github-actions[bot] in #5413

New Contributors

• @chreekat made their first contribution in #5358
• @KunJeong made their first contribution in #5369

Full Changelog: v1.2.5.8...v1.2.5.9