Consistently use "region" terminology in later stages of the compiler

[WaffleLapkin]

Proposal

This includes the following renames:

• GenericArgKind::{Lifetime => Region}
• tcx.{lifetimes => regions}
  • CommonLifetimes => CommonRegions
  • CommonRegions::{re_erased => erased, re_vars => vars, re_late_bounds => late_bounds}
    - re_static was left as-is (static is a keyword...)

The reasoning is that most things in the later stages already use "region" terminology and this will be more consistent. As an example GenericArgKind::Lifetime currently wraps ty::Region, which is odd.

While we may want to consider different names in the future, I don't thinks that that conflicts with this proposal, if anything it'll be easier to rename to a different name if everything uses the same terminology; consistency in the moment matters.

Mentors or Reviewers

This is a simple rename, that doesn't necessarily need mentors.

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

[apiraino]

Closing MCP since supersed by rust-lang/rust#110254 (that proposal discussed on Zulip)

[WaffleLapkin]

@apiraino "since" is a bit weird, rust-lang/rust#110254 was opened before this MCP...

[apiraino]

@WaffleLapkin you're right, I mixed up a bit the timeline of events. By reading the discussion on Zulip I got that the agreement was that this proposal was going in the opposite direction of rust-lang/rust#110254 (opened later tha this MCP) and #451 (started much earlier of this MCP AFAICS). Thus this proposal was not seconded.