Fix scoping for let chains in match guards #119554

matthewjasper · 2024-01-03T17:29:04Z

If let guards were previously represented as a different type of guard in HIR and THIR. This meant that let chains in match guards were not handled correctly because they were treated exactly like normal guards.

Remove hir::Guard and thir::Guard.
Make the scoping different between normal guards and if let guards also check for let chains.

closes #118593

rustbot · 2024-01-03T17:29:11Z

r? @WaffleLapkin

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rustbot · 2024-01-03T17:29:14Z

Changes to the size of AST and/or HIR nodes.

cc @nnethercote

Some changes might have occurred in exhaustiveness checking

cc @Nadrieril

compiler-errors · 2024-01-03T17:45:36Z

compiler/rustc_hir/src/hir.rs

@@ -1258,7 +1258,7 @@ pub struct Arm<'hir> {
    /// If this pattern and the optional guard matches, then `body` is evaluated.
    pub pat: &'hir Pat<'hir>,
    /// Optional guard clause.
-    pub guard: Option<Guard<'hir>>,


Ah, I've always been so confused why this was represented differently in HIR. This was also what caused the bug fixed by #119402, for example.

I think if_let_guards was implemented before let chains were ready. But it's definitely outstayed its usefulness.

rustbot · 2024-01-04T10:29:59Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

compiler-errors

One question below.

compiler/rustc_mir_build/src/build/matches/mod.rs

compiler-errors · 2024-01-04T15:33:10Z

@rustbot author

Use Expr instead. Use `ExprKind::Let` to represent if let guards.

Match guards with an if let guard or an if let chain guard should have a temporary scope of the whole arm. This is to allow ref bindings to temporaries to borrow check.

matthewjasper · 2024-01-05T11:45:08Z

@rustbot ready

compiler-errors · 2024-01-05T14:44:29Z

@bors r+

bors · 2024-01-05T14:44:31Z

📌 Commit 44bba54 has been approved by compiler-errors

It is now in the queue for this repository.

…tion, r=compiler-errors Fix scoping for let chains in match guards If let guards were previously represented as a different type of guard in HIR and THIR. This meant that let chains in match guards were not handled correctly because they were treated exactly like normal guards. - Remove `hir::Guard` and `thir::Guard`. - Make the scoping different between normal guards and if let guards also check for let chains. closes rust-lang#118593

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#118680 (Add support for shell argfiles) - rust-lang#119151 (Hide foreign `#[doc(hidden)]` paths in import suggestions) - rust-lang#119350 (Imply outlives-bounds on lazy type aliases) - rust-lang#119354 (Make `negative_bounds` internal & fix some of its issues) - rust-lang#119506 (Use `resolutions(()).effective_visiblities` to avoid cycle errors in `report_object_error`) - rust-lang#119554 (Fix scoping for let chains in match guards) - rust-lang#119563 (Check yield terminator's resume type in borrowck) - rust-lang#119589 (cstore: Remove unnecessary locking from `CrateMetadata`) r? `@ghost` `@rustbot` modify labels: rollup

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#119151 (Hide foreign `#[doc(hidden)]` paths in import suggestions) - rust-lang#119350 (Imply outlives-bounds on lazy type aliases) - rust-lang#119354 (Make `negative_bounds` internal & fix some of its issues) - rust-lang#119506 (Use `resolutions(()).effective_visiblities` to avoid cycle errors in `report_object_error`) - rust-lang#119554 (Fix scoping for let chains in match guards) - rust-lang#119563 (Check yield terminator's resume type in borrowck) - rust-lang#119589 (cstore: Remove unnecessary locking from `CrateMetadata`) - rust-lang#119622 (never patterns: Document behavior of never patterns with macros-by-example) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#119554 - matthewjasper:remove-guard-distinction, r=compiler-errors Fix scoping for let chains in match guards If let guards were previously represented as a different type of guard in HIR and THIR. This meant that let chains in match guards were not handled correctly because they were treated exactly like normal guards. - Remove `hir::Guard` and `thir::Guard`. - Make the scoping different between normal guards and if let guards also check for let chains. closes rust-lang#118593

…tion, r=compiler-errors Fix scoping for let chains in match guards If let guards were previously represented as a different type of guard in HIR and THIR. This meant that let chains in match guards were not handled correctly because they were treated exactly like normal guards. - Remove `hir::Guard` and `thir::Guard`. - Make the scoping different between normal guards and if let guards also check for let chains. closes rust-lang#118593

matthewjasper added F-let_chains `#![feature(let_chains)]` F-if_let_guard `#![feature(if_let_guard)]` labels Jan 3, 2024

rustbot assigned WaffleLapkin Jan 3, 2024

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 Jan 3, 2024

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compiler-errors assigned compiler-errors and unassigned WaffleLapkin Jan 4, 2024

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 4, 2024

matthewjasper force-pushed the remove-guard-distinction branch from 43d59ba to 6c935b3 Compare January 4, 2024 17:20

matthewjasper added 4 commits January 5, 2024 10:56

Remove hir::Guard

407cb24

Use Expr instead. Use `ExprKind::Let` to represent if let guards.

Remove thir::Guard

a549711

Use Expr instead. Use `ExprKind::Let` to represent if let guards.

Restore if let guard temporary scoping difference

1a267e3

Match guards with an if let guard or an if let chain guard should have a temporary scope of the whole arm. This is to allow ref bindings to temporaries to borrow check.

Update clippy for hir::Guard removal

44bba54

matthewjasper force-pushed the remove-guard-distinction branch from 6c935b3 to 44bba54 Compare January 5, 2024 10:57

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 5, 2024

compiler-errors approved these changes Jan 5, 2024

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bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 5, 2024

matthiaskrgr mentioned this pull request Jan 5, 2024

Rollup of 8 pull requests #119623

Closed

matthiaskrgr mentioned this pull request Jan 5, 2024

Rollup of 8 pull requests #119630

Closed

matthiaskrgr mentioned this pull request Jan 5, 2024

Rollup of 8 pull requests #119634

Merged

bors merged commit 958417f into rust-lang:master Jan 5, 2024
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rustbot added this to the 1.77.0 milestone Jan 5, 2024

dingxiangfei2009 mentioned this pull request Jan 7, 2024

Add new temporary lifetime feature gate and super let keyword #119043

Closed

matthewjasper deleted the remove-guard-distinction branch January 8, 2024 12:54

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Fix scoping for let chains in match guards #119554

Fix scoping for let chains in match guards #119554

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Fix scoping for let chains in match guards #119554

Fix scoping for let chains in match guards #119554

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