feat: ic-cdk and ic-cdk-macros v0.20.2 — interpret empty vector as candid encoding of () - #711
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Pull request overview
This PR makes the ic-cdk entrypoint macros (update, query, init, post_upgrade) more permissive by treating an empty msg_arg_data() payload (vec![]) as the Candid “no-arguments” encoding, allowing methods with optional parameters to decode missing inputs as None.
Changes:
- Adjust macro-generated argument decoding to treat an empty input blob as Candid-encoded “no args” (
()), even when the method signature expects arguments. - Add end-to-end coverage to ensure
vec![]is accepted for methods takingOption<...>arguments (update + query). - Document the behavior change in the
ic-cdkchangelog.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.
| File | Description |
|---|---|
ic-cdk/CHANGELOG.md |
Documents the new empty-input decoding behavior for entry points. |
ic-cdk-macros/src/export.rs |
Implements the empty-input-as-() decoding behavior in macro output (and updates macro expansion tests). |
e2e-tests/tests/macros.rs |
Adds integration assertions that empty binary input is accepted for optional-arg methods. |
e2e-tests/src/bin/macros/main.rs |
Introduces foo_update / foo_query canister methods (with Option<u64> args) used by the new e2e test. |
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mraszyk
marked this pull request as ready for review
June 8, 2026 15:14
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Decode the empty-input args from a &[u8] slice pointing at the static Candid header (DIDL\0\0) instead of allocating a Vec<u8> on every call with empty input. Addresses Copilot review feedback on #711. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
lwshang
changed the title
lwshang
approved these changes
Jun 8, 2026
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Description
This PR fixes the CDK macros for update, query,
init, andpost_upgrademethods to interpret an empty input vector as the Candid encoding of()even if the method has a non-empty argument list. The motivation is to allow passing an empty input vector to method taking optional arguments and have them be decoded toNoneby default.This PR also releases ic-cdk and ic-cdk-macros v0.20.2 (version bumps in the workspace + crate manifests and the corresponding
ic-cdkCHANGELOG entry).How Has This Been Tested?
New integration tests have been introduced.
Checklist: