deref patterns: lower deref patterns to MIR #122598

Nadrieril · 2024-03-16T14:53:26Z

This lowers deref patterns to MIR. This is a bit tricky because this is the first kind of pattern that requires storing a value in a temporary. Thanks to #123324 false edges are no longer a problem.

The thing I'm not confident about is the handling of fake borrows. This PR ignores any fake borrows inside a deref pattern. We are guaranteed to at least fake borrow the place of the first pointer value, which could be enough, but I'm not certain.

Nadrieril · 2024-03-16T17:01:35Z

cc @fee1-dead @BoxyUwU if you're curious

Nadrieril · 2024-04-04T18:57:04Z

This is ready!

@rustbot ready

r? @matthewjasper

rustbot · 2024-04-07T15:31:31Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

This PR changes MIR

cc @oli-obk, @RalfJung, @JakobDegen, @davidtwco, @celinval, @vakaras

This PR changes Stable MIR

cc @oli-obk, @celinval, @ouz-a

Nadrieril · 2024-04-07T15:33:29Z

The only sensible solution I found to solve the fake borrows issue is to add non-shallow fake borrows to MIR and use that. That's a nontrivial change though.

compiler/stable_mir/src/mir/body.rs

compiler/rustc_middle/src/mir/syntax.rs

compiler/stable_mir/src/mir/pretty.rs

compiler/rustc_middle/src/mir/pretty.rs

compiler/rustc_middle/src/mir/syntax.rs

bors · 2024-04-16T02:43:14Z

☔ The latest upstream changes (presumably #123991) made this pull request unmergeable. Please resolve the merge conflicts.

compiler/rustc_middle/src/mir/syntax.rs

This handles using deref patterns to choose the correct match arm. This does not handle bindings or guards. Co-authored-by: Deadbeef <ent3rm4n@gmail.com>

matthewjasper · 2024-04-23T15:07:54Z

@bors r+

bors · 2024-04-23T15:07:57Z

📌 Commit 726fb55 has been approved by matthewjasper

It is now in the queue for this repository.

Rollup of 7 pull requests Successful merges: - rust-lang#120929 (Wrap dyn type with parentheses in suggestion) - rust-lang#122591 (Suggest using type args directly instead of equality constraint) - rust-lang#122598 (deref patterns: lower deref patterns to MIR) - rust-lang#123048 (alloc::Layout: explicitly document size invariant on the type level) - rust-lang#123993 (Do `check_coroutine_obligations` once per typeck root) - rust-lang#124218 (Allow nesting subdiagnostics in #[derive(Subdiagnostic)]) - rust-lang#124285 (Mark ``@RUSTC_BUILTIN`` search path usage as unstable) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#122598 - Nadrieril:full-derefpats, r=matthewjasper deref patterns: lower deref patterns to MIR This lowers deref patterns to MIR. This is a bit tricky because this is the first kind of pattern that requires storing a value in a temporary. Thanks to rust-lang#123324 false edges are no longer a problem. The thing I'm not confident about is the handling of fake borrows. This PR ignores any fake borrows inside a deref pattern. We are guaranteed to at least fake borrow the place of the first pointer value, which could be enough, but I'm not certain.

rustbot assigned pnkfelix Mar 16, 2024

This comment was marked as resolved.

# to view

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Mar 16, 2024