I'm not saying Rust doesn't do this. I'm not familiar with Rust but many languages do NRVO as you point out. The important distinction is whether we actually ru

I'm not saying Rust doesn't do this. I'm not familiar with Rust but many languages do NRVO as you point out. The important distinction is whether we actually run additional instructions in this variant of the optimization. In C++ at least, no additional instructions are run.