Merge commit '0e87918536b9833bbc6c683d1f9d51ee2bf03ef1' into clippyup

[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 f77f0b380157d2905ea53dead0117c70ace993a9..e93de8a252a34befc63b1aac34164f0bf266213b 100644 (file)
--- a/clippy_lints/src/needless_update.rs
+++ b/clippy_lints/src/needless_update.rs
@@ -1,13 +1,16 @@
-use crate::utils::span_lint;
-use rustc::lint::{LateContext, LateLintPass};
-use rustc::ty;
+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
     /// 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.
     ///
@@ -21,6 +24,16 @@
     /// #     z: i32,
     /// # }
     /// # let zero_point = Point { x: 0, y: 0, z: 0 };
+    ///
+    /// // Bad
+    /// Point {
+    ///     x: 1,
+    ///     y: 1,
+    ///     z: 1,
+    ///     ..zero_point
+    /// };
+    ///
+    /// // Ok
     /// Point {
     ///     x: 1,
     ///     y: 1,
@@ -34,12 +47,14 @@
 
 declare_lint_pass!(NeedlessUpdate => [NEEDLESS_UPDATE]);
 
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NeedlessUpdate {
-    fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
+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 {
-            let ty = cx.tables.expr_ty(expr);
-            if let ty::Adt(def, _) = ty.kind {
-                if fields.len() == def.non_enum_variant().fields.len() {
+            let ty = cx.typeck_results().expr_ty(expr);
+            if let ty::Adt(def, _) = ty.kind() {
+                if fields.len() == def.non_enum_variant().fields.len()
+                    && !def.variants[0_usize.into()].is_field_list_non_exhaustive()
+                {
                     span_lint(
                         cx,
                         NEEDLESS_UPDATE,