Tracking Issue for short backtraces in the default panic hook

[jyn514]

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

About tracking issues

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Steps

Compile-time

• Parse, validate, and emit the new #[rustc_{skip,start,end}_short_backtrace] attributes in rustc itself ([experimental] shorten backtraces using debuginfo #134831). Currently blocked on everything else.
• Extend LLVM to emit the appropriate debuginfo (Generate DW_AT_RUST_short_backtrace attributes for DISubprogram nodes llvm/llvm-project#123683)
  • Waiting on pre-RFC
• Extend rustc_codegen_cranelift to emit the appropriate debuginfo ([experimental] shorten backtraces using debuginfo #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 (Add UnitRef::shared_attrs gimli-rs/gimli#756). Waiting on me to rework the API in response to review comments.
• Update backtrace-rs to pass the debuginfo through to libstd (Parse short backtraces out of debuginfo backtrace-rs#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 ([experimental] shorten backtraces using debuginfo #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