fix(candid_parser): emit Float32 for Candid float32 in Motoko binding#728
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Previously, the Motoko binding generator panicked with "float32 not supported in Motoko" when encountering a `float32` type. This was correct per the spec at the time, but Motoko added `Float32` support in version 1.4.0 (caffeinelabs/motoko#5906), updating both the import and export mappings. The spec has now been updated accordingly. Adds a test fixture (float.did) covering float32/float64 round-trip methods to prevent regression. Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: Cursor <cursoragent@cursor.com>
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Pull request overview
This PR updates the Motoko binding generator in candid_parser to support Candid float32 by emitting Motoko’s Float32 type (instead of panicking), and adds a golden test fixture to lock in the expected outputs across all binding targets.
Changes:
- Motoko binding: map Candid
float32to MotokoFloat32instead of panicking at runtime. - Add
float.didtest fixture + corresponding golden outputs (.did,.mo,.rs,.js,.d.ts) to coverfloat32/float64method signatures. - Document the change in
CHANGELOG.mdunder Unreleased.
Reviewed changes
Copilot reviewed 7 out of 8 changed files in this pull request and generated no comments.
Show a summary per file
| File | Description |
|---|---|
| rust/candid_parser/src/bindings/motoko.rs | Stops panicking on float32 and emits Float32 in generated Motoko bindings. |
| rust/candid_parser/tests/assets/float.did | Adds a new input fixture exercising float32/float64 usage in a service. |
| rust/candid_parser/tests/assets/ok/float.did | Golden pretty-printed .did output for the new fixture. |
| rust/candid_parser/tests/assets/ok/float.mo | Golden Motoko binding output verifying Float32 emission. |
| rust/candid_parser/tests/assets/ok/float.rs | Golden Rust binding output for the new fixture. |
| rust/candid_parser/tests/assets/ok/float.js | Golden JS binding output covering IDL.Float32/IDL.Float64. |
| rust/candid_parser/tests/assets/ok/float.d.ts | Golden TS declaration output for the new fixture. |
| CHANGELOG.md | Notes the Motoko float32 binding bug fix under Unreleased. |
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ggreif
changed the title
Float32 for Candid float32 in Motoko binding
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Summary
panic!("float32 not supported in Motoko")withstr("Float32")in the Motoko binding generator.float.didtest fixture coveringfloat32/float64round-trip methods.Why
Motoko added
Float32in version 1.4.0 (dfinity/motoko#5906), updating both the import and export IDL mappings. The spec (design/IDL-Motoko.md) is being updated in a companion PR. This bringsdidc bind --target moin line with whatmocalready does when importing.didfiles directly.Concretely, any
.didfile usingfloat32(e.g. the IC management canister interface) would previously causedidc bind --target moto panic at runtime.