Reference return type from fallible Rust function does not compile

[dtolnay]

use anyhow::Result;

#[cxx::bridge]
mod ffi {
    extern "Rust" {
        fn test() -> Result<&'static i32>;
    }
}

fn test() -> Result<&'static i32> {
    Ok(&0)
}

The return type is being implemented by a pointer out-parameter, and it's not possible for that pointer to point to a reference in C++.

$ cargo check
target/debug/build/example-283878198746b170/out/cxxbridge/sources/example/src/main.rs.cc:80:60: error: 'return$' declared as a pointer to a reference of type 'const ::std::int32_t &' (aka 'const int &')
::rust::repr::PtrLen cxxbridge1$test(const ::std::int32_t &*return$) noexcept;
                                                           ^
target/debug/build/example-283878198746b170/out/cxxbridge/sources/example/src/main.rs.cc:51:5: error: union member 'value' has reference type 'const int &'
  T value;
    ^
target/debug/build/example-283878198746b170/out/cxxbridge/sources/example/src/main.rs.cc:84:47: note: in instantiation of template class 'rust::cxxbridge1::MaybeUninit<const int &>' requested here
  ::rust::MaybeUninit<const ::std::int32_t &> return$;
                                              ^