Point at return type when it influences non-first `match` arm #114819

estebank · 2023-08-14T18:36:45Z

When encountering code like

fn foo() -> i32 {
    match 0 {
        1 => return 0,
        2 => "",
        _ => 1,
    }
}

Point at the return type and not at the prior arm, as that arm has type ! which isn't influencing the arm corresponding to arm 2.

Fix #78124.

rustbot · 2023-08-14T18:36:52Z

r? @jackh726

(rustbot has picked a reviewer for you, use r? to override)

compiler-errors · 2023-08-14T18:42:46Z

compiler/rustc_middle/src/traits/mod.rs

@@ -402,7 +402,7 @@ pub enum ObligationCauseCode<'tcx> {
    OpaqueReturnType(Option<(Ty<'tcx>, Span)>),

    /// Block implicit return
-    BlockTailExpression(hir::HirId),
+    BlockTailExpression(hir::HirId, hir::HirId, hir::MatchSource),


Can you make these fields have names?

compiler/rustc_hir_typeck/src/_match.rs

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

rustbot · 2023-08-14T19:27:24Z

Some changes might have occurred in exhaustiveness checking

cc @Nadrieril

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

When encountering code like ```rust fn foo() -> i32 { match 0 { 1 => return 0, 2 => "", _ => 1, } } ``` Point at the return type and not at the prior arm, as that arm has type `!` which isn't influencing the arm corresponding to arm `2`. Fix rust-lang#78124.

compiler-errors

r=me if ci passes

compiler-errors · 2023-08-14T22:06:32Z

src/tools/clippy/tests/ui/if_same_then_else2.rs

@@ -98,7 +98,7 @@ fn if_same_then_else2() -> Result<&'static str, ()> {
    };

    if true {
-        //~^ ERROR: this `if` has identical blocks
+        // FIXME: should emit "this `if` has identical blocks"


Do you know why this regressed?

compiler-errors · 2023-08-15T02:28:26Z

@bors r+

bors · 2023-08-15T02:28:29Z

📌 Commit 58aa903 has been approved by compiler-errors

It is now in the queue for this repository.

…rrors Point at return type when it influences non-first `match` arm When encountering code like ```rust fn foo() -> i32 { match 0 { 1 => return 0, 2 => "", _ => 1, } } ``` Point at the return type and not at the prior arm, as that arm has type `!` which isn't influencing the arm corresponding to arm `2`. Fix rust-lang#78124.

flip1995 · 2023-08-15T20:30:02Z

src/tools/clippy/clippy_utils/src/check_proc_macro.rs

@@ -149,7 +149,7 @@ fn expr_search_pat(tcx: TyCtxt<'_>, e: &Expr<'_>) -> (Pat, Pat) {
            (Pat::Str("for"), Pat::Str("}"))
        },
        ExprKind::Match(_, _, MatchSource::Normal) => (Pat::Str("match"), Pat::Str("}")),
-        ExprKind::Match(e, _, MatchSource::TryDesugar) => (expr_search_pat(tcx, e).0, Pat::Str("?")),
+        ExprKind::Match(e, _, MatchSource::TryDesugar(_)) => (expr_search_pat(tcx, e).0, Pat::Str("?")),


This might be the reason for the Clippy regression. Did the expression e that is stored in the ExprKind::Match change by any chance and that's why re-calling expr_search_pat leads to different results than before? 🤔

(Pretty wild guess)

I'll take a look

Fixing in #115122

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#114588 (Improve docs for impl Default for ExitStatus) - rust-lang#114619 (Fix pthread_attr_union layout on Wasi) - rust-lang#114644 (Point out expectation even if we have `TypeError::RegionsInsufficientlyPolymorphic`) - rust-lang#114668 (Deny `FnDef` in patterns) - rust-lang#114819 (Point at return type when it influences non-first `match` arm) - rust-lang#114826 (Fix typos) - rust-lang#114837 (add missing feature(error_in_core)) - rust-lang#114853 (Migrate GUI colors test to original CSS color format) r? `@ghost` `@rustbot` modify labels: rollup

Follow up to rust-lang#114819.

Fix clippy lint for identical `if`/`else` contraining `?` expressions Follow up to rust-lang#114819.

…rrors Point at return type when it influences non-first `match` arm When encountering code like ```rust fn foo() -> i32 { match 0 { 1 => return 0, 2 => "", _ => 1, } } ``` Point at the return type and not at the prior arm, as that arm has type `!` which isn't influencing the arm corresponding to arm `2`. Fix rust-lang#78124.

Follow up to rust-lang#114819.

rustbot assigned jackh726 Aug 14, 2023

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 Aug 14, 2023

compiler-errors reviewed Aug 14, 2023

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estebank added 4 commits August 14, 2023 21:43

Move scrutinee HirId into MatchSource::TryDesugar

5021dde

review comment: add claryfing comment

298ca67

bless clippy test

58aa903

estebank force-pushed the issue-78124 branch from 459997b to 58aa903 Compare August 14, 2023 22:00

compiler-errors approved these changes Aug 14, 2023

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compiler-errors assigned compiler-errors and unassigned jackh726 Aug 14, 2023

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 Aug 15, 2023

matthiaskrgr mentioned this pull request Aug 15, 2023

Rollup of 4 pull requests #114835

Closed

matthiaskrgr mentioned this pull request Aug 15, 2023

Rollup of 7 pull requests #114857

Closed

This was referenced Aug 15, 2023

Rollup of 10 pull requests #114863

Closed

Rollup of 8 pull requests #114864

Merged

flip1995 reviewed Aug 15, 2023

View reviewed changes

bors merged commit 8db5a6d into rust-lang:master Aug 15, 2023

rustbot added this to the 1.73.0 milestone Aug 15, 2023

estebank added a commit to estebank/rust that referenced this pull request Aug 23, 2023

Fix clippy lint for identical if/else contraining ? expressions

91cf04d

Follow up to rust-lang#114819.

estebank mentioned this pull request Aug 23, 2023

Fix clippy lint for identical if/else contraining ? expressions #115122

Merged

matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request Aug 23, 2023

Rollup merge of rust-lang#115122 - estebank:fix-clippy, r=Manishearth

e777fd4

Fix clippy lint for identical `if`/`else` contraining `?` expressions Follow up to rust-lang#114819.

Dylan-DPC added a commit to Dylan-DPC/rust that referenced this pull request Aug 23, 2023

Rollup merge of rust-lang#115122 - estebank:fix-clippy, r=Manishearth

867a12d

Fix clippy lint for identical `if`/`else` contraining `?` expressions Follow up to rust-lang#114819.

flip1995 pushed a commit to flip1995/rust that referenced this pull request Aug 24, 2023

Fix clippy lint for identical if/else contraining ? expressions

32eecd4

Follow up to rust-lang#114819.

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Point at return type when it influences non-first `match` arm #114819

Point at return type when it influences non-first `match` arm #114819

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Point at return type when it influences non-first match arm #114819

Point at return type when it influences non-first match arm #114819

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Point at return type when it influences non-first `match` arm #114819

Point at return type when it influences non-first `match` arm #114819