diff options
| -rw-r--r-- | clippy_lints/src/manual_let_else.rs | 7 | ||||
| -rw-r--r-- | tests/ui/manual_let_else_match.rs | 29 | ||||
| -rw-r--r-- | tests/ui/manual_let_else_match.stderr | 15 |
3 files changed, 46 insertions, 5 deletions
diff --git a/clippy_lints/src/manual_let_else.rs b/clippy_lints/src/manual_let_else.rs index 9c6f8b43c07..9eacb383514 100644 --- a/clippy_lints/src/manual_let_else.rs +++ b/clippy_lints/src/manual_let_else.rs @@ -115,6 +115,13 @@ impl<'tcx> LateLintPass<'tcx> for ManualLetElse { .enumerate() .find(|(_, arm)| expr_diverges(cx, arm.body) && pat_allowed_for_else(cx, arm.pat, check_types)); let Some((idx, diverging_arm)) = diverging_arm_opt else { return; }; + // If the non-diverging arm is the first one, its pattern can be reused in a let/else statement. + // However, if it arrives in second position, its pattern may cover some cases already covered + // by the diverging one. + // TODO: accept the non-diverging arm as a second position if patterns are disjointed. + if idx == 0 { + return; + } let pat_arm = &arms[1 - idx]; if !expr_is_simple_identity(pat_arm.pat, pat_arm.body) { return; diff --git a/tests/ui/manual_let_else_match.rs b/tests/ui/manual_let_else_match.rs index 28caed9d79d..73b74679125 100644 --- a/tests/ui/manual_let_else_match.rs +++ b/tests/ui/manual_let_else_match.rs @@ -42,13 +42,13 @@ fn fire() { loop { // More complex pattern for the identity arm and diverging arm let v = match h() { - (Some(_), Some(_)) | (None, None) => continue, (Some(v), None) | (None, Some(v)) => v, + (Some(_), Some(_)) | (None, None) => continue, }; // Custom enums are supported as long as the "else" arm is a simple _ let v = match build_enum() { - _ => continue, Variant::Bar(v) | Variant::Baz(v) => v, + _ => continue, }; } @@ -71,6 +71,12 @@ fn fire() { Variant::Bar(_) | Variant::Baz(_) => (), _ => return, }; + + let data = [1_u8, 2, 3, 4, 0, 0, 0, 0]; + let data = match data.as_slice() { + [data @ .., 0, 0, 0, 0] | [data @ .., 0, 0] | [data @ .., 0] => data, + _ => return, + }; } fn not_fire() { @@ -125,4 +131,23 @@ fn not_fire() { Ok(v) | Err(Variant::Bar(v) | Variant::Baz(v)) => v, Err(Variant::Foo) => return, }; + + // Issue 10241 + // The non-divergent arm arrives in second position and + // may cover values already matched in the first arm. + let v = match h() { + (Some(_), Some(_)) | (None, None) => return, + (Some(v), _) | (None, Some(v)) => v, + }; + + let v = match build_enum() { + _ => return, + Variant::Bar(v) | Variant::Baz(v) => v, + }; + + let data = [1_u8, 2, 3, 4, 0, 0, 0, 0]; + let data = match data.as_slice() { + [] | [0, 0] => return, + [data @ .., 0, 0, 0, 0] | [data @ .., 0, 0] | [data @ ..] => data, + }; } diff --git a/tests/ui/manual_let_else_match.stderr b/tests/ui/manual_let_else_match.stderr index cd5e9a9ac39..7abaa0b85d2 100644 --- a/tests/ui/manual_let_else_match.stderr +++ b/tests/ui/manual_let_else_match.stderr @@ -22,8 +22,8 @@ error: this could be rewritten as `let...else` --> $DIR/manual_let_else_match.rs:44:9 | LL | / let v = match h() { -LL | | (Some(_), Some(_)) | (None, None) => continue, LL | | (Some(v), None) | (None, Some(v)) => v, +LL | | (Some(_), Some(_)) | (None, None) => continue, LL | | }; | |__________^ help: consider writing: `let ((Some(v), None) | (None, Some(v))) = h() else { continue };` @@ -31,8 +31,8 @@ error: this could be rewritten as `let...else` --> $DIR/manual_let_else_match.rs:49:9 | LL | / let v = match build_enum() { -LL | | _ => continue, LL | | Variant::Bar(v) | Variant::Baz(v) => v, +LL | | _ => continue, LL | | }; | |__________^ help: consider writing: `let (Variant::Bar(v) | Variant::Baz(v)) = build_enum() else { continue };` @@ -63,5 +63,14 @@ LL | | _ => return, LL | | }; | |______^ help: consider writing: `let (Variant::Bar(_) | Variant::Baz(_)) = f else { return };` -error: aborting due to 7 previous errors +error: this could be rewritten as `let...else` + --> $DIR/manual_let_else_match.rs:76:5 + | +LL | / let data = match data.as_slice() { +LL | | [data @ .., 0, 0, 0, 0] | [data @ .., 0, 0] | [data @ .., 0] => data, +LL | | _ => return, +LL | | }; + | |______^ help: consider writing: `let ([data @ .., 0, 0, 0, 0] | [data @ .., 0, 0] | [data @ .., 0]) = data.as_slice() else { return };` + +error: aborting due to 8 previous errors |