Auto merge of #9148 - arieluy:then_some_unwrap_or, r=Jarcho

[rust.git] / clippy_lints / src / needless_update.rs

diff --git a/clippy_lints/src/needless_update.rs b/clippy_lints/src/needless_update.rs
index 98e9078094a225b0f9acaee37eb4e32c3c231163..0bd29d1776b28e714dc2438f7a675fa632887fca 100644 (file)
--- a/clippy_lints/src/needless_update.rs
+++ b/clippy_lints/src/needless_update.rs
@@ -1,19 +1,22 @@
-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,
@@ -21,22 +24,24 @@
     /// #     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"
@@ -46,10 +51,12 @@
 
 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 fields.len() == def.non_enum_variant().fields.len()
+                    && !def.variant(0_usize.into()).is_field_list_non_exhaustive()
+                {
                     span_lint(
                         cx,
                         NEEDLESS_UPDATE,