Transfer rustc-demangle to the @rust-lang GitHub org.

[eddyb]

Proposal

Both the Rust standard library and rustc depend on rustc-demangle, for demangling symbol names in RUST_BACKTRACE output, and (de)mangling tests, respectively.
Outside of rust-lang/rust uses, rustc-demangle is also used in the ecosystem by tools like rustfilt and other projects that may e.g. analyze binaries/profiles/etc. which could contain mangled Rust symbols.
It even has a C API (added in rust-lang/rustc-demangle#14), for integrating it into non-Rust projects that want to support handling Rust symbols.

The crate is currently under @alexcrichton's account, i.e. at alexcrichton/rustc-demangle, but I believe that it being the official Rust symbol name demangler warrants moving it to the @rust-lang organization.

Additionally, unlike other std/rustc dependencies, its implementation needs to co-evolve with rustc's mangling implementation (and we've seen this with the v0 mangling over the past couple years), in order to remain maximally useful.

Regarding rust-lang/rfcs#3119 classifications, "Intentional artifacts" seems more appropriate, as it has users in the wider ecosystem, and we prefer it being used, than the demangling algorithms getting reimplemented.

I'm not entirely sure that the compiler team is the best choice to maintain it, but I'm leaning towards it given the co-evolution aspect between mangling and demangling.

Mentors or Reviewers

Process

The main points of the Major Change Process are as follows:

• File an issue describing the proposal.
• A compiler team member or contributor who is knowledgeable in the area can second by writing @rustbot second.
  • Finding a "second" suffices for internal changes. If however, you are proposing a new public-facing feature, such as a -C flag, then full team check-off is required.
  • Compiler team members can initiate a check-off via @rfcbot fcp merge on either the MCP or the PR.
• Once an MCP is seconded, the Final Comment Period begins. If no objections are raised after 10 days, the MCP is considered approved.

You can read more about Major Change Proposals on forge.

Comments

This issue is not meant to be used for technical discussion. There is a Zulip stream for that. Use this issue to leave procedural comments, such as volunteering to review, indicating that you second the proposal (or third, etc), or raising a concern that you would like to be addressed.

[rustbot]

This issue is not meant to be used for technical discussion. There is a Zulip stream for that. Use this issue to leave procedural comments, such as volunteering to review, indicating that you second the proposal (or third, etc), or raising a concern that you would like to be addressed.

cc @rust-lang/compiler @rust-lang/compiler-contributors

[wesleywiser]

@rustbot second

[apiraino]

@rustbot label -final-comment-period +major-change-accepted