The Rust compiler only takes 45 minutes to build if you're also including the time to build LLVM from scratch. Given that the page mentions V's "Clang backend"

The Rust compiler only takes 45 minutes to build if you're also including the time to build LLVM from scratch. Given that the page mentions V's "Clang backend" and later asserts that Clang takes one hour to build, that means that it's fair to say that the V compiler builds itself in one hour and one second.