fix: match_single_binding suggests wrongly inside tuple

Author: profetia

clippy_lints/src/matches/match_single_binding.rs

@@ -307,26 +307,6 @@ fn expr_in_nested_block(cx: &LateContext<'_>, match_expr: &Expr<'_>) -> bool {
     false
 }
 
-fn expr_must_have_curlies(cx: &LateContext<'_>, match_expr: &Expr<'_>) -> bool {
-    let parent = cx.tcx.parent_hir_node(match_expr.hir_id);
-    if let Node::Expr(Expr {
-        kind: ExprKind::Closure(..) | ExprKind::Binary(..),
-        ..
-    })
-    | Node::AnonConst(..) = parent
-    {
-        return true;
-    }
-
-    if let Node::Arm(arm) = &cx.tcx.parent_hir_node(match_expr.hir_id)
-        && let ExprKind::Match(..) = arm.body.kind
-    {
-        return true;
-    }
-
-    false
-}
-
 fn indent_of_nth_line(snippet: &str, nth: usize) -> Option<usize> {
     snippet
         .lines()
@@ -379,14 +359,42 @@ fn sugg_with_curlies<'a>(
 
     let mut indent = " ".repeat(indent_of(cx, ex.span).unwrap_or(0));
     let (mut cbrace_start, mut cbrace_end) = (String::new(), String::new());
-    if !expr_in_nested_block(cx, match_expr)
-        && ((needs_var_binding && is_var_binding_used_later) || expr_must_have_curlies(cx, match_expr))
-    {
+    let mut add_curlies = || {
         cbrace_end = format!("\n{indent}}}");
         // Fix body indent due to the closure
         indent = " ".repeat(indent_of(cx, bind_names).unwrap_or(0));
         cbrace_start = format!("{{\n{indent}");
         snippet_body = reindent_snippet_if_in_block(&snippet_body, !assignment_str.is_empty());
+    };
+
+    if !expr_in_nested_block(cx, match_expr) {
+        let mut parent = cx.tcx.parent_hir_node(match_expr.hir_id);
+        if let Node::Expr(Expr {
+            kind: ExprKind::Assign(..),
+            hir_id,
+            ..
+        }) = parent
+        {
+            parent = cx.tcx.parent_hir_node(*hir_id);
+        }
+        if let Node::Stmt(stmt) = parent {
+            parent = cx.tcx.parent_hir_node(stmt.hir_id);
+        }
+
+        match parent {
+            Node::Block(..)
+            | Node::Expr(Expr {
+                kind: ExprKind::Block(..) | ExprKind::ConstBlock(..),
+                ..
+            }) => {
+                if needs_var_binding && is_var_binding_used_later {
+                    add_curlies();
+                }
+            },
+            Node::Expr(..) | Node::AnonConst(..) => add_curlies(),
+            Node::Arm(arm) if let ExprKind::Match(..) = arm.body.kind => add_curlies(),
+            _ => {},
+        }
     }
 
     format!("{cbrace_start}{scrutinee};\n{indent}{assignment_str}{snippet_body}{cbrace_end}")

tests/ui/match_single_binding.fixed

@@ -265,3 +265,82 @@ fn issue15269(a: usize, b: usize, c: usize) -> bool {
     a < b
         && b < c
 }
+
+#[allow(
+    irrefutable_let_patterns,
+    clippy::blocks_in_conditions,
+    clippy::unused_unit,
+    clippy::let_unit_value,
+    clippy::unit_arg,
+    clippy::unnecessary_operation
+)]
+fn issue15537(a: i32) -> ((), (), ()) {
+    let y = (
+        { todo!() },
+        {
+            { a };
+            ()
+        },
+        (),
+    );
+
+    let y = [
+        { todo!() },
+        {
+            { a };
+            ()
+        },
+        (),
+    ];
+
+    fn call(x: (), y: (), z: ()) {}
+    let y = call(
+        { todo!() },
+        {
+            { a };
+            ()
+        },
+        (),
+    );
+
+    struct Foo;
+    impl Foo {
+        fn method(&self, x: (), y: (), z: ()) {}
+    }
+    let x = Foo;
+    x.method(
+        { todo!() },
+        {
+            { a };
+            ()
+        },
+        (),
+    );
+
+    -{
+        { a };
+        1
+    };
+
+    _ = { a };
+    1;
+
+    if let x = {
+        { a };
+        1
+    } {}
+
+    if {
+        { a };
+        true
+    } {
+        todo!()
+    }
+
+    [1, 2, 3][{
+        { a };
+        1usize
+    }];
+
+    todo!()
+}

tests/ui/match_single_binding.rs

@@ -342,3 +342,84 @@ fn issue15269(a: usize, b: usize, c: usize) -> bool {
             (a, b) => b < c,
         }
 }
+
+#[allow(
+    irrefutable_let_patterns,
+    clippy::blocks_in_conditions,
+    clippy::unused_unit,
+    clippy::let_unit_value,
+    clippy::unit_arg,
+    clippy::unnecessary_operation
+)]
+fn issue15537(a: i32) -> ((), (), ()) {
+    let y = (
+        { todo!() },
+        match { a } {
+            //~^ match_single_binding
+            _ => (),
+        },
+        (),
+    );
+
+    let y = [
+        { todo!() },
+        match { a } {
+            //~^ match_single_binding
+            _ => (),
+        },
+        (),
+    ];
+
+    fn call(x: (), y: (), z: ()) {}
+    let y = call(
+        { todo!() },
+        match { a } {
+            //~^ match_single_binding
+            _ => (),
+        },
+        (),
+    );
+
+    struct Foo;
+    impl Foo {
+        fn method(&self, x: (), y: (), z: ()) {}
+    }
+    let x = Foo;
+    x.method(
+        { todo!() },
+        match { a } {
+            //~^ match_single_binding
+            _ => (),
+        },
+        (),
+    );
+
+    -match { a } {
+        //~^ match_single_binding
+        _ => 1,
+    };
+
+    _ = match { a } {
+        //~^ match_single_binding
+        _ => 1,
+    };
+
+    if let x = match { a } {
+        //~^ match_single_binding
+        _ => 1,
+    } {}
+
+    if match { a } {
+        //~^ match_single_binding
+        _ => true,
+    } {
+        todo!()
+    }
+
+    [1, 2, 3][match { a } {
+        //~^ match_single_binding
+        _ => 1usize,
+    }];
+
+    todo!()
+}