Description
Proposal
Similarly to queries, we should also have a scheme to register functions in a very lightweight manner. This would allow us to have implementations in crates that come after rustc_middle while being able to call said functions from any crate that has access to TyCtxt. While one could use a query for that in many cases, as already mentioned queries are expensive, but additionally, not everything can be in a query argument. Query arguments must be StableHash, which can be problematic.
More concretely, with such a scheme we would have an easy way to fix rust-lang/rust#77650 and rust-lang/rust#77708 (some discussion in https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/incremental.20const_evaluatable_checked.20bug/near/221163894)
Mentors or Reviewers
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 mergeon either the MCP or the PR.
- Finding a "second" suffices for internal changes. If however you are proposing a new public-facing feature, such as a
- 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.