1 files changed, 135 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/manual_let_else_match.fixed b/src/tools/clippy/tests/ui/manual_let_else_match.fixed
new file mode 100644
index 000000000..09b713f04
--- /dev/null
+++ b/src/tools/clippy/tests/ui/manual_let_else_match.fixed
@@ -0,0 +1,135 @@
+#![allow(unused_braces, unused_variables, dead_code)]
+#![allow(
+    clippy::collapsible_else_if,
+    clippy::let_unit_value,
+    clippy::redundant_at_rest_pattern
+)]
+#![warn(clippy::manual_let_else)]
+// Ensure that we don't conflict with match -> if let lints
+#![warn(clippy::single_match_else, clippy::single_match)]
+
+fn f() -> Result<u32, u32> {
+    Ok(0)
+}
+
+fn g() -> Option<()> {
+    None
+}
+
+fn h() -> (Option<()>, Option<()>) {
+    (None, None)
+}
+
+enum Variant {
+    Foo,
+    Bar(u32),
+    Baz(u32),
+}
+
+fn build_enum() -> Variant {
+    Variant::Foo
+}
+
+fn main() {}
+
+fn fire() {
+    let Some(v) = g() else { return };
+
+    let Some(v) = g() else { return };
+
+    loop {
+        // More complex pattern for the identity arm and diverging arm
+        let ((Some(v), None) | (None, Some(v))) = h() else { continue };
+        // Custom enums are supported as long as the "else" arm is a simple _
+        let (Variant::Bar(v) | Variant::Baz(v)) = build_enum() else { continue };
+    }
+
+    // There is a _ in the diverging arm
+    // TODO also support unused bindings aka _v
+    let Ok(v) = f() else { return };
+
+    // Err(()) is an allowed pattern
+    let Ok(v) = f().map_err(|_| ()) else { return };
+
+    let f = Variant::Bar(1);
+
+    let (Variant::Bar(_value) | Variant::Baz(_value)) = f else { return };
+
+    let Some(Variant::Bar(_value) | Variant::Baz(_value)) = Some(build_enum()) else { return };
+
+    let data = [1_u8, 2, 3, 4, 0, 0, 0, 0];
+    let ([data @ .., 0, 0, 0, 0] | [data @ .., 0, 0] | [data @ .., 0]) = data.as_slice() else { return };
+}
+
+fn not_fire() {
+    // Multiple diverging arms
+    let v = match h() {
+        _ => panic!(),
+        (None, Some(_v)) => return,
+        (Some(v), None) => v,
+    };
+
+    // Multiple identity arms
+    let v = match h() {
+        _ => panic!(),
+        (None, Some(v)) => v,
+        (Some(v), None) => v,
+    };
+
+    // No diverging arm at all, only identity arms.
+    // This is no case for let else, but destructuring assignment.
+    let v = match f() {
+        Ok(v) => v,
+        Err(e) => e,
+    };
+
+    // The identity arm has a guard
+    let v = match g() {
+        Some(v) if g().is_none() => v,
+        _ => return,
+    };
+
+    // The diverging arm has a guard
+    let v = match f() {
+        Err(v) if v > 0 => panic!(),
+        Ok(v) | Err(v) => v,
+    };
+
+    // The diverging arm creates a binding
+    let v = match f() {
+        Ok(v) => v,
+        Err(e) => panic!("error: {e}"),
+    };
+
+    // Custom enum where the diverging arm
+    // explicitly mentions the variant
+    let v = match build_enum() {
+        Variant::Foo => return,
+        Variant::Bar(v) | Variant::Baz(v) => v,
+    };
+
+    // The custom enum is surrounded by an Err()
+    let v = match Err(build_enum()) {
+        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,
+    };
+}