Add parenthesis around closure method call

src/chains.rs

@@ -253,11 +253,7 @@ impl ChainItemKind {
                 return (
                     ChainItemKind::Parent {
                         expr: expr.clone(),
-                        parens: is_method_call_receiver
-                            && matches!(
-                                &expr.kind,
-                                ast::ExprKind::Lit(lit) if crate::expr::lit_ends_in_dot(lit)
-                            ),
+                        parens: is_method_call_receiver && should_add_parens(expr),
                     },
                     expr.span,
                 );
@@ -982,3 +978,22 @@ fn trim_tries(s: &str) -> String {
     }
     result
 }
+
+/// Whether a method call's receiver needs parenthesis, like
+/// ```rust,ignore
+/// || .. .method();
+/// || 1.. .method();
+/// 1. .method();
+/// ```
+/// Which all need parenthesis or a space before `.method()`.
+fn should_add_parens(expr: &ast::Expr) -> bool {
+    match expr.kind {
+        ast::ExprKind::Lit(ref lit) => crate::expr::lit_ends_in_dot(lit),
+        ast::ExprKind::Closure(ref cl) => match cl.body.kind {
+            ast::ExprKind::Range(_, _, ast::RangeLimits::HalfOpen) => true,
+            ast::ExprKind::Lit(ref lit) => crate::expr::lit_ends_in_dot(lit),
+            _ => false,
+        },
+        _ => false,
+    }
+}

tests/source/issue-4808.rs

@@ -0,0 +1,19 @@
+trait Trait {
+    fn method(&self);
+}
+
+impl<F: Fn() -> T, T> Trait for F {
+    fn method(&self) {}
+}
+
+trait Trait {
+    fn method(&self) {}
+}
+
+impl Trait for f32 {}
+
+fn main() {
+    || 10. .method();
+    || .. .method();
+    || 1.. .method();
+}

tests/target/issue-4808.rs

@@ -0,0 +1,19 @@
+trait Trait {
+    fn method(&self);
+}
+
+impl<F: Fn() -> T, T> Trait for F {
+    fn method(&self) {}
+}
+
+trait Trait {
+    fn method(&self) {}
+}
+
+impl Trait for f32 {}
+
+fn main() {
+    || (10.).method();
+    (|| ..).method();
+    (|| 1..).method();
+}