dtolnay/cxx 0.5.3

on GitHub

Add an item-level #[namespace = "..."] attribute to specify the C++ namespace path of an individual type or function (#370, #380, thanks @adetaylor)

#[cxx::bridge]
mod ffi {
    #[namespace = "the::path::of"]
    struct Thing {...}

    extern "C++" {
        #[namespace = "some::where::else"]
        fn function() -> Thing;
    }
}

Emit diagnostic on include! paths relative to . or .., as the positioning of generated code inside of Cargo's OUT_DIR is not specified (#368, #375)

Treat C++ constructors rust::String(nullptr, 0) and rust::Str(nullptr, 0) as creating empty strings; previously UB (#383)

Enable rust::Str and rust::Slice<T> to be passed in registers by C++ (#387)

Eliminate warning from rustc 1.46+ when using function pointers in the signature of an extern C++ function (#396)

Support single Rust source file containing multiple #[cxx::bridge] modules (#397)

Expose a way to bypass is_trivially_destructible/_move_constructible check on extern types passed by value (#406)

// IsRelocatable<T> is used in assertions that a C++ type passed by value
// between Rust and C++ is soundly relocatable by Rust.
//
// There may be legitimate reasons to opt out of the check for support of types
// that the programmer knows are soundly Rust-movable despite not being
// recognized as such by the C++ type system due to a move constructor or
// destructor. To opt out of the relocatability check, do either of the
// following things in any header used by `include!` in the bridge.
//
//      --- if you define the type:
//      struct MyType {
//        ...
//    +   using IsRelocatable = std::true_type;
//      };
//
//      --- otherwise:
//    + template <>
//    + struct rust::IsRelocatable<MyType> : std::true_type {};
template <typename T>
struct IsRelocatable;

Fix error on pass-by-reference of a shared struct containing a Rust String to a C++ function (#408)

Make shared structs order-independent such that a struct is able to contain a field whose type is another shared struct defined later in the same FFI module (#411)