-use crate::utils::span_lint;
+use clippy_utils::diagnostics::span_lint;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty;
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
- /// **What it does:** Checks for needlessly including a base struct on update
+ /// ### What it does
+ /// Checks for needlessly including a base struct on update
/// when all fields are changed anyway.
///
- /// **Why is this bad?** This will cost resources (because the base has to be
- /// somewhere), and make the code less readable.
+ /// This lint is not applied to structs marked with
+ /// [non_exhaustive](https://doc.rust-lang.org/reference/attributes/type_system.html).
///
- /// **Known problems:** None.
+ /// ### Why is this bad?
+ /// This will cost resources (because the base has to be
+ /// somewhere), and make the code less readable.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # struct Point {
/// # x: i32,
/// # z: i32,
/// # }
/// # let zero_point = Point { x: 0, y: 0, z: 0 };
- ///
- /// // Bad
/// Point {
/// x: 1,
/// y: 1,
/// z: 1,
/// ..zero_point
/// };
+ /// ```
///
- /// // Ok
+ /// Use instead:
+ /// ```rust,ignore
+ /// // Missing field `z`
/// Point {
/// x: 1,
/// y: 1,
/// ..zero_point
/// };
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub NEEDLESS_UPDATE,
complexity,
"using `Foo { ..base }` when there are no missing fields"
impl<'tcx> LateLintPass<'tcx> for NeedlessUpdate {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
- if let ExprKind::Struct(_, ref fields, Some(ref base)) = expr.kind {
+ if let ExprKind::Struct(_, fields, Some(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 let ty::Adt(def, _) = ty.kind() {
+ if fields.len() == def.non_enum_variant().fields.len()
+ && !def.variant(0_usize.into()).is_field_list_non_exhaustive()
+ {
span_lint(
cx,
NEEDLESS_UPDATE,