[bascule]

Not quite. Try this:

    import "os"

    func main() {
	    os.Open("this file does not exist")
    }

This will compile just fine, producing no compiler error or warnings whatsoever. The error is just silently ignored.

Compare to Rust:

    use std::fs::File;

    fn main() {
        File::open("this file does not exist");
    }

This will produce the following warning:

    warning: unused result which must be used
      --> test.rs:14:5
       |
    14 |     File::open("this file does not exist");
       |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
       |
       = note: #[warn(unused_must_use)] on by default

This example is a bit contrived, because if you open a file you probably want to do something with it. But imagine something where the only return value you care about is the error, like say "txn.commit()"

[mbel]

A slightly related note: you can get similar behavior in C (and C++) with compiler extensions. In GCC and clang marking function with '__attribute__((warn_unused_result))' will produce a warning if function is called without using the result. Equivalent for MSVC is '_Check_return_'.

Obviously this is not nearly as convenient as your Rust example, but enables some of its the benefits.

[gpderetta]

C++17 has (will have?) [[nodiscard]] with the same semantics.