Tracking Issue for short backtraces in the default panic hook

This is a tracking issue for short backtraces in the default panic hook (https://github.com/rust-lang/rust/issues/124586, https://github.com/rust-lang/compiler-team/issues/818). See previous Zulip discussion.

About tracking issues

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They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.
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Steps

Compile-time

• Parse, validate, and emit the new #[rustc_{skip,start,end}_short_backtrace] attributes in rustc itself (https://github.com/rust-lang/rust/pull/134831). Currently blocked on everything else.
• Extend LLVM to emit the appropriate debuginfo (https://github.com/llvm/llvm-project/pull/123683)
  • Waiting on pre-RFC
• Extend rustc_codegen_cranelift to emit the appropriate debuginfo (https://github.com/rust-lang/rust/pull/134831). Blocked.
• Extend rustc_codegen_gcc to emit the appropriate debuginfo. Waiting on me or Antoyo to implement it.

Runtime

• Extend either addr2line or gimli to give backtrace-rs a way to find the appropriate debuginfo (https://github.com/gimli-rs/gimli/pull/756). Waiting on me to rework the API in response to review comments.
• Update backtrace-rs to pass the debuginfo through to libstd (https://github.com/rust-lang/backtrace-rs/pull/693). Waiting on the gimli PR and for me to have time to debug this on macOS.
• Update the default panic hook to use the debuginfo (https://github.com/rust-lang/rust/pull/134831). Blocked on everything else.

Unresolved Questions

• How should we represent the debuginfo at runtime? The current three-state enum doesn't allow both marking a frame as the end of a push/pop pair while also omitting it in the backtrace. NOTE: please leave comments about this on LLVM discourse, not on this issue.
• How can we extend this to PDB? Right now it only works for DWARF. Possibly we can use llvm.codeview.annotation?

Implementation history

See above.

@rustbot label T-compiler T-libs A-runtime A-backtrace A-debuginfo

Start by reviewing the unchecked compile-time and runtime items, especially rust-lang/rust PR 134831, the LLVM pre-RFC, and the linked gimli and backtrace-rs PRs. Done requires resolving the listed compiler, debuginfo, runtime, and panic-hook dependencies, but the issue shows that several remain blocked or under discussion.