3 ms·

Stage2 is like a Band-Aid on an amputee. It is built with stage1. Any compiler built such that `if (false)` branches can run will also miscompile code, even if

• kprotty 4y ago
  1) Stage2 is intended as more than just fixes for stage1; It includes performance improvements, more codegen backends (direct x86/arm/wasm to avoid LLVM, C, etc.), will allow for incremental linking, hot reloading, and more. 2) The miscompilation in question is `if (false) else |capture| {}` not just `if (false)`. The latter is misinformation. 3) Miscompilations are conditional. Saying that the entire compiler is invalid given they exist is like saying rustc is invalid / can't uphold safety invariants given long standing compiler bugs allowing safe code to trigger UB / segfault [0] [1]. Both of such conclusions aren't true in practice. [0]: https://crates.io/crates/fake-static https://crates.io/crates/fake-static [1]: https://github.com/rust-lang/rust/issues/25860 https://github.com/rust-lang/rust/issues/25860
• kristoff_it 4y ago
  It's not uncommon for LLVM releases to come with regressions that cause miscompilations. The compiler toolchain industry is very different from what you seem to think it is.