Function __rcopy_is_copy_shim 

#[doc(hidden)]
unsafe extern "C" fn __rcopy_is_copy_shim<__ImplT: RCopy + IntoR>(
    data: *mut c_void,
    argc: i32,
    argv: *const SEXP,
) -> SEXP

Method shim for RCopy::is_copy.

Converts SEXP arguments, calls the method, and returns SEXP result. Both Rust panics and R longjmps are caught via with_r_unwind_protect.