Store ICE backtraces to disk and point end users at the file location

[estebank]

Proposal

Modify rustc's panic handler to always store ICE backtraces and the query stack, as well as other minimal debugging-relevant information (platform, rustc version) to a file on disk. Modify the presented output to be less intrusive (we would no longer print out a wall of inscrutable text unless RUSTC_BACKTRACE=full is set and hope people notice the instructions) and include instructions on how to find the file and submit a ticket. When RUSTC_BACKTRACE=full isn't set and a backtrace wouldn't be printed, we'd print the backtrace to disk.

Mentors or Reviewers

@estebank

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

I've created a draft PR to experiment on what was technically feasible and I am satisfied with the results.

[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

[compiler-errors]

@rustbot second

[compiler-errors]

Hm, well seems like there's a bit more discussion in the zulip thread. Perhaps we should pause this MCP for now, at least until discussion has settled?

[apiraino]

@compiler-errors No problem, I'll tentatively revert the FCP until the discussion settles. Please feel free to second again (or anyone else) later on.

@rustbot label -final-comment-period

[oli-obk]

@rustbot second

[apiraino]

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