Cx Dev Log — 2026-04-25

Source: Dev.to

Breaking through the six‑day stagnation on submain

We’ve finally hit a major milestone with four committed changes pushing Cx 0.1 over to release‑candidate status. A significant memory‑boundary audit unveiled a critical StrRef soundness bug, now resolved, and all nine hard blockers are cleared, leaving the merge gap as the last major step before declaring release.

Commit a576f20

• Touches: parser.rs, semantic.rs, main.rs, runtime.rs
• Adds six new matrix tests (t109 to t114)
• Refactors the type parser from flat alternatives to a recursive() approach, enabling parsing of nested types like Result and Handle, previously a roadblock for complex generics.

Semantic pass improvements

• Enhances field‑type resolution from struct definitions for DotAccess LValues.
• Rejects mismatched types.
• apply_numeric_cast in runtime now adapts using the declared type of LValues for both Assign and CompoundAssign.

Runtime stack upgrade

• Introduces a dedicated 64 MB stack thread for the interpreter, safeguarding against stack overflow in recursive Cx programs.

Stats: 17 files changed, net increase of 119 lines.

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Commit 41099fb – Memory‑audit examples

Added 12 targeted test programs in examples/audit_memory/, scrutinizing:

• Handle lifecycle
• Copy semantics
• String arena operations

Results

• 9 tests passed cleanly
• 1 known limitation on arena growth (accepted for v0.1)
• 1 intentional semantic rejection
• 1 critical soundness bug identified (fixed in the next commit)

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Fix for the crucial StrRef issue (b057340)

The bug allowed StrRef values into struct fields, bypassing current escape checks that block such entries in variable assignments and function returns.

• New safety layers in semantic.rs now block these potential escapes during struct‑field assignment and instantiation.
• Added matrix test t115 confirms the fix with a planned failure, ensuring stricter scope adherence for arena‑backed string references.
• No additional escape paths were found, but vigilance remains key.

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Three pivotal decisions shaping the future

StrRef and struct fields

All StrRef escape routes via struct fields have been shut off, aligning with the existing policy and sealing the last loophole.

Handle double‑drop as silent no‑op

The audit confirmed that the handle’s generational indexing safely handles double‑drops without incident. Future releases may add warnings, but for now it remains a silent guardian.

64 MB interpreter stack approach

A simple solution—allocating a 64 MB stack on a dedicated thread—solves stack‑overflow issues for recursive Cx programs without complex per‑frame tweaks. It’s efficient for v0.1; further reductions are planned.

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Charting the roadmap to v5.0 and beyond

Commit 587bd20 escalates the submain roadmap to v5.0, removing all nine barrier benchmarks. Known limitations are now transparent.

• Submain: 19 new commits
• Main: ~15 commits pending integration

The upcoming merge will boost the main matrix from 78 to 117 tests, incorporating all hard‑blocker resolutions.

Post‑merge focus

• Operational tidying (e.g., daily‑log branches)
• Enhancing the quality gate with := type inference and pattern‑matching advancements
• IR lowering for new constructs

These are not immediate blockers for v0.1 but will improve the developer experience in future versions.

All soundness issues are patched, all blockers resolved, and the path from RC to stable release is clear. The next steps are integration and refinement to bring Cx 0.1 to stable release.

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