candid

• Non-breaking changes:
  • Upgrade candid_parser dependency to v0.4.0.

2026-06-23

• Non-breaking changes:
  • didc check now reports all incompatible changes at once, grouped by method, instead of stopping at the first error
  • Clearer error messages: e.g. "missing in new interface" and "function annotation changed from query to update"

• Non-breaking changes:
  • fix: ignore inline comments or separated by newlines

2025-09-15

• Breaking changes:
  • The didc test subcommand has been removed.

• Bug fixes:
  • Escape the method names of a service type in the Rust binding. A Candid method name is an arbitrary text value, but pp_ty_service emitted it raw between the quotes of a Rust string literal inside candid::define_service!. A name containing " therefore closed the literal and the macro invocation, and the rest of the name was compiled as Rust — a .did file could inject arbitrary items into the bindings generated from it, and from there into the consumer's binary. Names are now escaped with escape_debug, as pp_function and the #[serde(rename)] attributes already were. The value seen by define_service! is unchanged, and names that are ordinary identifiers generate byte-identical output.

2026-08-11

• Breaking changes:
  • Parse and preserve named function arguments and results. The AST now carries argument names so consumers (e.g. binding generators) can emit meaningful parameter names:
    • New syntax::IDLArgType { typ: IDLType, name: Option<String> } with IDLArgType::new / IDLArgType::new_with_name. Purely numeric names are normalized to None.
    • syntax::FuncType::{args, rets}, syntax::IDLType::ClassT, syntax::IDLTypes::args, and syntax::IDLInitArgs::args now hold Vec<IDLArgType> instead of Vec<IDLType>.
    • The pretty-printer now round-trips argument names (e.g. (from : principal)).
  • Type checking is unchanged: names are dropped when lowering to candid::types::Function, so the candid crate is unaffected.

2026-05-27

• Non-breaking changes:
  • Add service_compatibility_report() returning a full grouped compatibility report as a string

• Breaking changes:
  • Changed imports generated by candid_parser::bindings::typescript::compile from @dfinity/* to @icp-sdk/core/*

• Non-breaking changes:
  • fix: escape */ to prevent premature JS doc comment termination

2025-10-26

• Non-breaking changes:
  • Rust binding: Sets service_name based on top level name config
  • Rust binding: Makes struct field and function names are more intuitive and predictable.
    • Rust binding convert identifiers into cases conforms to Rust naming convention. Since didc v0.5, some identifiers started to be renamed. E.g. struct field amount_e8s was renamed to amount_e_8_s. Now, field name like amount_e8s won't be renamed.
    • Please check to_identifier_case() in rust/candid_parser/src/bindings/rust/identifier.rs for more details.
    • Note: different identifiers might be converted to the same one, potentially causing naming conflicts. If this happens, you'll need to use the Type Selector Config to specify custom names.

2025-10-02

• Non-breaking changes:
  • fix: ignore inline comments or separated by newlines

• Breaking changes:

  • The candid_parser::types module has been renamed to candid_parser::syntax.

• Non-breaking changes:

  • Supports collecting line comments as doc comments in the following cases:

    • above services:

      // This is a valid doc comment for the service
      service : {
        greet : (text) -> (text);
      }
      

    • above actor methods:

      service : {
        // This is a valid doc comment for greet
        greet : (text) -> (text);
      }
      

    • above type declarations:

      // This is a valid doc comment for type A
      type A = record {
        my_field : text;
      };
      

    • above record and variant fields:

      type A = record {
        // This is a valid doc comment for my_field
        my_field : text;
      };
      
      type B = record {
        // This is a valid doc comment for nat element
        nat;
        text;
      }
      
      type C = variant {
        // This is a valid doc comment for my_variant_field
        my_variant_field : nat;
      };
      

  • Adds the IDLMergedProg struct, used to collect the syntax types when parsing Candid declarations.

  • Supports reflecting doc comments from Candid declarations to the generated bindings. To enable this feature, we had to change the following:

    • The candid_parser::bindings::motoko::compile function now takes an additional &IDLMergedProg parameter.
    • The candid_parser::bindings::rust::compile function now takes an additional &IDLMergedProg parameter.
    • The candid_parser::bindings::typescript::compile function now takes an additional &IDLMergedProg parameter.
    • The candid::pretty::syntax module has been added. It exposes the pretty_print function, which is used to pretty print the IDLMergedProg struct. The behavior is similar to the already existing candid::pretty::candid::compile function, but uses the syntax types instead of the candid types.

  • Supports reflecting doc comments from Rust canister methods to the Candid generated bindings. Example:

    /// Doc comment for greet,
    /// even on multiple lines
    #[candid_method(query)]
    fn greet(name: &str) -> String {
      format!("Hello, {name}!")
    }
    

    The generated Candid bindings will then look like this:

    service : {
      // Doc comment for greet,
      // even on multiple lines
      greet : (text) -> (text);
    }
    

    To support this feature, hhe following have been added:

    • candid::pretty::candid::DocComments struct, which is used to collect doc comments from Rust canister methods, in the candid_derive::export_service macro.
    • candid::pretty::candid::compile_with_docs function, which takes a &DocComments parameter.

• Add import service in parser to allow merging services.