Upgrade cel-rust 0.12 → 0.13 (then revisit 0.14 once released) #31

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1. hardbyte commented on May 12, 2026

   

   hardbyte

   on May 12, 2026

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   0.14 investigation — decision: hold

   Did an exploratory branch (cel-0.14-upgrade, local — kept in a stash) pointing cel at upstream main rev cc7c378. Findings inform the plan.

   Status of 0.14 upstream

   • Not yet released to crates.io. Release PR clarkmcc/cel-rust#279 has been open since 2026-03-12.
   • The struct work and most other 0.14 changes are already on master.

   Rust API surface

   Unchanged for us. Value::Struct is feature-gated behind structs, which we don't enable. Clean compile against cc7c378 with no source modifications.

   User-visible regressions

   1. min/max removed from the default stdlib (upstream now requires explicit context.add_function("min", cel::functions::min)). Fixable on our side by registering them in build_environment — already prototyped in the stash.
   2. Stdlib conversion overloads now shadow user-registered functions. cel 0.14 adds int/uint/double/string/bytes/duration/timestamp as overload-resolved stdlib functions. When a user calls context.add_function("double", their_fn), dispatch silently picks the stdlib cast (objects.rs:1331 — env consulted before user functions).
   3. Some test assertions need refreshing for fold/reduce error message changes — minor.

   What the CEL spec actually says

   Verified against langdef.md:

   • Type conversion functions (int, uint, double, …) are not reserved keywords — they're "normal functions". The reserved list is only as break const continue else for function if import let loop package namespace return var void while.
   • However, the "Extension Functions" section says: "An application domain of CEL can add a new overload to the size function above, provided this overload's argument types do not overlap with any existing overload."
   • Dispatch order between user-provided and standard functions is implementation-defined (not specified).

   So cel-rust 0.14's behaviour (stdlib wins on overlap) is closer to spec than "user functions should override stdlib" would be. Asking upstream to flip dispatch order isn't a spec-aligned ask.

   Workaround landscape (purely our side)

   • Hardcoded-name-list warning at Context.add_function — feasible (~30 LOC) but bit-rots and false-positives on legitimate non-overlapping extensions.
   • cel::Context::empty() escape hatch — too coarse; drops size, optional, time getters along with conversions.
   • Custom curated cel::Env — fragile; per-type stdlib() modules mix conversions + useful methods (bytes::stdlib adds both bytes() cast AND size_bytes), and reaching the internals would mean re-implementing upstream's registration logic.
   • Signature-overlap detection (what the spec actually constrains) requires upstream introspection API we don't have.

   Decision

   Ship the 0.13 PR (#32) as our next release. Hold on 0.14 until at least one of:

   1. Upstream releases 0.14 to crates.io (we want a stable target, not a git rev).
   2. Upstream adds an Env::remove_overload / Env::has_overload / similar introspection API that gives wrappers a clean way to handle the shadowing.

   Net 0.14 benefit for our wrapper is small — most of the marquee work (structs, Type lifetime cleanup) is behind features we don't enable or refactors we don't touch. Worth waiting for a clean target.

   The exploratory branch + stash are preserved locally for whenever we pick this back up.
2. hardbyte

   changed the title [-]Upgrade cel-rust 0.12 → 0.13 → 0.14[/-] [+]Upgrade cel-rust 0.12 → 0.13 (then revisit 0.14 once released)[/+] on May 12, 2026
3. hardbyte

   added a commit that references this issue on May 12, 2026

   Upgrade cel-rust to 0.13.0 and trim docs (#32)

   ...

   1075d86
4. hardbyte commented on Jul 4, 2026

   

   hardbyte

   on Jul 4, 2026

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   Resolved in v0.7.0, which upgraded straight to cel-rust 0.14 (past 0.13). See https://github.com/hardbyte/python-common-expression-language/releases/tag/v0.7.0
5. hardbyte

   closed this as completedon Jul 4, 2026