Ironic, but the one think they are missing is an easy convenient way to call C libraries.
Rust is very promising language, but unless you plan to write everything from scratch, you have to depend on 3rd party driver implementations for most stuff. Databases for example. There isn't a single database vendor that has Rust drivers.
Calling C from Rust is very convenient. All you have to do is declare the structs and function signatures and then it's like calling any other unsafe function.
IMHO it is OK if you are only going to call a few simple one, but for calling a few hundred complex ones (callbacks with variable argument list, etc..), it becomes a bit cumbersome.
BTW I am not implying that is Rust's fault, actually I can't think a syntax that would make it less verbose, and I am a huge Rust fan.
Not really, there are tools that can take C header files and spit out bindings. Rust also supports vararg C functions even though Rust itself doesn't support varargs. Writing safe Rust wrappers around these unsafe C bindings can sometimes be tedious, but this isn't worse than using C directly (which is inherently unsafe).
For very extensive C APIs like this (Lua, GTK, etc.) we typically see people create thin, Rust-friendly wrappers to reduce the amount of manual API calls that need to be written out.
