26f4b72724
Use `Freeze` for `SourceFile` This uses the `Freeze` type in `SourceFile` to let accessing `external_src` and `lines` be lock-free. Behavior of `add_external_src` is changed to set `ExternalSourceKind::AbsentErr` on a hash mismatch which matches the documentation. `ExternalSourceKind::Unneeded` was removed as it's unused. Based on https://github.com/rust-lang/rust/pull/115401.
This directory contains some source code for the Rust project, including:
- The bootstrapping build system
- Various submodules for tools, like cargo, tidy, etc.
For more information on how various parts of the compiler work, see the rustc dev guide.