[kbolino]

Neither Go nor Rust define an ABI for themselves. They can use dynamically linked C code just fine but cannot link their own language with all (or even a reasonably broad subset) of its own features. This is not as bad in Rust, where you can fall back to the unsafe C ABI while still having safe Rust on either side, whereas Go cannot have two instances of its runtime active in the same process.

Compare this situation with Java/JVM or C#/.NET, both of which define their own ABIs albeit not for native machine code, or especially Swift, which defines its own native-code ABI.