Rename various internal things

[oli-obk]

Proposal

There are some things in rustc that are named historically or just really oddly. I would like to rename them to reflect what they are without having to understand Rust's history and/or programming language design/theory jargon.

• Region -> Lifetime in general. While Region kinda makes more sense, we use Lifetime in the language
• EarlyBoundRegion -> GenericLifetime (to reflect what they are in the language)
• LateBoundRegion ->HigherRankedLifetime (")
• *Folder and fold_* -> *Replacer and replace_*
• Substs -> GenericArgs
• subst -> replace_generics

Mentors or Reviewers

@oli-obk, @eddyb

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

[eddyb]

@rustbot second (specifically, I would prefer if moved past the confusing "folder" and "substs" terminology, feels like it's long overdue - the other changes seem like they don't have to be done at the same time)

[apiraino]

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