Add `-Z unpretty` flags for the AST and the THIR

[LeSeulArtichaut]

Proposal

Add a few -Z (perma-unstable) flags to dump a representation of the AST and THIR, akin to -Zunpretty=hir-tree for the HIR:

• -Zunpretty=ast-tree and -Zunpretty=ast-tree,expanded for the AST
• -Zunpretty=thir-tree for the THIR

Being able to dump those IRs is always useful when hacking on the compiler. Also, this is something we (the rustc-dev-guide WG) would like to have for rust-lang/rustc-dev-guide#1062, to be able to better teach those IRs.

Mentors or Reviewers

Implemented in rust-lang/rust#82304, looking for a reviewer

Process

The main points of the Major Change Process is 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

[estebank]

@rustbot second