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Document some porting bits

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Johannes Altmanninger 2023-02-08 23:45:30 +01:00
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doc_internal/rust-devel.md
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@ -65,6 +65,14 @@ You will likely run into limitations of [`autocxx`](https://google.github.io/aut
## Type Mapping
### Constants & Type Aliases
The FFI does not support constants (`#define` or `static const`) or type aliases (`typedef`, `using`). Duplicate them using their Rust equivalent (`pub const` and `type`/`struct`/`enum`).
### Non-POD types
Many types cannot currently be passed across the language boundary by value or occur in shared structs. As a workaround, use references, raw pointers or smart pointers (`cxx` provides `SharedPtr` and `UniquePtr`). Try to keep workarounds on the C++ side and the FFI layer of the Rust code. This ensures we will get rid of the workarounds as we peel off the FFI layer.
### Strings
Fish will mostly _not_ use Rust's `String/&str` types as these cannot represent non-UTF8 data using the default encoding.
@ -141,6 +149,8 @@ pub fn get_jobs(ffi_jobs: &ffi::RustFFIJobList) -> &[SharedPtr<job_t>] {
}
```
Another workaround is to define a struct that contains the shared pointer, and create a vector of that struct.
## Development Tooling
The [autocxx guidance](https://google.github.io/autocxx/workflow.html#how-can-i-see-what-bindings-autocxx-has-generated) is helpful: