Retrobootstrapping Rust for some reason

a year ago

Rust's initial compiler, rustboot, was written in OCaml and emitted 32-bit i386 machine code.
The transition to rustc (using LLVM) involved a bootstrap process: stage0 (rustboot on rustc), stage1 (stage0 on rustc), and stage2 (stage1 on rustc) for verification.
Bitrot issues complicate retrobootstrapping due to changes in tools, compilers, and libraries over 14 years.
Debian's EOL Docker images provide a viable environment for retrobootstrapping Rust's initial bootstrap and fixpoint.
The correct Rust commit for the fixpoint is 6daf440037cb10baab332fde2b471712a3a42c76 from April 2011.
LLVM version 45e1a53efd40a594fa8bb59aee75bb0984770d29 (or equivalent SVN commit) is required for compatibility.
Performance observations: stage0 (rustboot) was faster to build but produced slower code, with LLVM providing a 2x speed boost at 3x the binary size.
Modern Rust's bootstrap is slower due to increased codebase size (600kloc vs. initial 25kloc).

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