Generate UniFFI bindings for C++. uniffi-bindgen-cpp lives as a separate project from uniffi-rs, as per uniffi-rs #1355.

How to install

Minimum Rust version required to install uniffi-bindgen-cpp is 1.74. Newer Rust versions should also work fine.

cargo install uniffi-bindgen-cpp --git https://github.com/NordSecurity/uniffi-bindgen-cpp --tag v0.8.1+v0.29.4

How to generate bindings

Generating with a single UDL file

uniffi-bindgen-cpp path/to/definitions.udl

Generating using a library file

uniffi-bindgen-cpp --library your_rust_library.so --out-dir output_directory

Regardless of the generation method, these files are produced:

• path/to/definitions.hpp
• path/to/definitions.cpp
• path/to/definitions_scaffolding.hpp

How to integrate bindings

To integrate the bindings into your projects, simply add the generated bindings files to your project. C++20 is required to compile the bindings.

Unsupported features

The following uniffi features are unsupported.

• External types
• Async functions

Configuration options

It's possible to configure some settings by passing --config argument to the generator.

Note: configuration is not supported when using library mode

uniffi-bindgen-cpp path/to/definitions.udl --config path/to/uniffi.toml

C++ Scaffolding

It is possible to generate C++ uniffi scaffolding that allows bridging C++ code with any other uniffi supported language (except Rust). More documentation and limitations can be found in the scaffolding documentation

Versioning

uniffi-bindgen-cpp is versioned separately from uniffi-rs. UniFFI follows the SemVer rules from the Cargo Book which states "Versions are considered compatible if their left-most non-zero major/minor/patch component is the same". A breaking change is any modification to the C++ bindings that demands the consumer of the bindings to make corresponding changes to their code to ensure that the bindings continue to function properly. uniffi-bindgen-cpp is young, and it's unclear how stable the generated bindings are going to be between versions. For this reason, major version is currently 0, and most changes are probably going to bump minor version.

To ensure consistent feature set across external binding generators, uniffi-bindgen-cpp targets a specific uniffi-rs version. A consumer using Go bindings (in uniffi-bindgen-go) and C# bindings (in uniffi-bindgen-cs) expects the same features to be available across multiple bindings generators. This means that the consumer should choose external binding generator versions such that each generator targets the same uniffi-rs version.

To simplify this choice uniffi-bindgen-cpp, uniffi-bindgen-cs and uniffi-bindgen-go use tag naming convention as follows: vX.Y.Z+vA.B.C, where X.Y.Z is the version of the generator itself, and A.B.C is the version of uniffi-rs it is based on.

The table shows uniffi-rs version history for tags that were published before tag naming convention described above was introduced.

uniffi-bindgen-cpp version	uniffi-rs version
v0.1.0	v0.25.0
v0.2.0	v0.25.0
v0.2.1	v0.25.0
v0.2.2	v0.25.0
v0.7.0	v0.28.3
v0.8.0	v0.29.4

Documentation

More documentation is available in docs directory.

Contributing

For contribution guidelines, read CONTRIBUTING.md.