# Where the beta compiler(maybe stage0?) come from? **URL:** \ **Category:** compiler\ **Created:** [May 15, 2026, 9:29am UTC](https://internals.rust-lang.org/t/where-the-beta-compiler-maybe-stage0-come-from/24304 "2026-05-15T09:29:02Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![curtainp](https://sea2.discourse-cdn.com/flex002/user_avatar/internals.rust-lang.org/curtainp/32/14323_2.png) [@curtainp](https://internals.rust-lang.org/u/curtainp)\ **Post date:** [May 15, 2026, 9:29am UTC](https://internals.rust-lang.org/t/where-the-beta-compiler-maybe-stage0-come-from/24304/1 "2026-05-15T09:29:02Z")
Hello everyone, I'm new here, when I follow the rustc guide to setup my local environment and notice there's a beta compiler which called stage0 compiler, I'm curious about where it come from, I discover that there is a stage0 file within `src/stage0` which indicate where to download it, but it already a binary, So how does the beta compiler is produced? ---
**Author:** ![kornel](https://sea2.discourse-cdn.com/flex002/user_avatar/internals.rust-lang.org/kornel/32/2711_2.png) [@kornel](https://internals.rust-lang.org/u/kornel)\ **Post date:** [May 15, 2026, 10:03am UTC](https://internals.rust-lang.org/t/where-the-beta-compiler-maybe-stage0-come-from/24304/2 "2026-05-15T10:03:49Z")
It's a previous build of the compiler, which has been built with previous build of the compiler, which has been built with previous build of the compiler… which has been built by a Rust prototype compiler written in Ocaml. If you want to build Rust fully from source without using pre-built binary, this process is called bootstrapping. See mrustc compiler. ---
**Author:** ![curtainp](https://sea2.discourse-cdn.com/flex002/user_avatar/internals.rust-lang.org/curtainp/32/14323_2.png) [@curtainp](https://internals.rust-lang.org/u/curtainp)\ **Post date:** [May 15, 2026, 11:08am UTC](https://internals.rust-lang.org/t/where-the-beta-compiler-maybe-stage0-come-from/24304/3 "2026-05-15T11:08:49Z")
thanks, bro. I just get it !