diff --git a/clippy_lints/src/needless_update.rs b/clippy_lints/src/needless_update.rs index 98e9078094a2..41cf541ecf5e 100644 --- a/clippy_lints/src/needless_update.rs +++ b/clippy_lints/src/needless_update.rs @@ -8,6 +8,9 @@ declare_clippy_lint! { /// **What it does:** Checks for needlessly including a base struct on update /// when all fields are changed anyway. /// + /// This lint is not applied to structs marked with + /// [non_exhaustive](https://doc.rust-lang.org/reference/attributes/type_system.html). + /// /// **Why is this bad?** This will cost resources (because the base has to be /// somewhere), and make the code less readable. /// @@ -49,7 +52,9 @@ impl<'tcx> LateLintPass<'tcx> for NeedlessUpdate { if let ExprKind::Struct(_, ref fields, Some(ref base)) = expr.kind { let ty = cx.typeck_results().expr_ty(expr); if let ty::Adt(def, _) = ty.kind() { - if fields.len() == def.non_enum_variant().fields.len() { + if fields.len() == def.non_enum_variant().fields.len() + && !def.variants[0_usize.into()].is_field_list_non_exhaustive() + { span_lint( cx, NEEDLESS_UPDATE, diff --git a/tests/ui/needless_update.rs b/tests/ui/needless_update.rs index bfa005a19f91..b93ff048a62f 100644 --- a/tests/ui/needless_update.rs +++ b/tests/ui/needless_update.rs @@ -6,9 +6,20 @@ struct S { pub b: i32, } +#[non_exhaustive] +struct T { + pub x: i32, + pub y: i32, +} + fn main() { let base = S { a: 0, b: 0 }; S { ..base }; // no error S { a: 1, ..base }; // no error S { a: 1, b: 1, ..base }; + + let base = T { x: 0, y: 0 }; + T { ..base }; // no error + T { x: 1, ..base }; // no error + T { x: 1, y: 1, ..base }; // no error } diff --git a/tests/ui/needless_update.stderr b/tests/ui/needless_update.stderr index 133c834880dd..b154b3b306dd 100644 --- a/tests/ui/needless_update.stderr +++ b/tests/ui/needless_update.stderr @@ -1,5 +1,5 @@ error: struct update has no effect, all the fields in the struct have already been specified - --> $DIR/needless_update.rs:13:23 + --> $DIR/needless_update.rs:19:23 | LL | S { a: 1, b: 1, ..base }; | ^^^^