Auto merge of #4809 - iankronquist:patch-1, r=flip1995

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

diff --git a/clippy_lints/src/large_enum_variant.rs b/clippy_lints/src/large_enum_variant.rs
index 79ff0c84bceae4e82ca22a9289475a2e7ec5da6f..0cd02f21238d22d896786296acd105dce8a71964 100644 (file)
--- a/clippy_lints/src/large_enum_variant.rs
+++ b/clippy_lints/src/large_enum_variant.rs
@@ -1,39 +1,29 @@
-// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-
 //! lint when there is a large size difference between variants on an enum
 
-use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use crate::rustc::{declare_tool_lint, lint_array};
-use crate::rustc::hir::*;
 use crate::utils::{snippet_opt, span_lint_and_then};
-use crate::rustc::ty::layout::LayoutOf;
-use crate::rustc_errors::Applicability;
+use rustc::ty::layout::LayoutOf;
+use rustc_errors::Applicability;
+use rustc_hir::*;
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
 
-/// **What it does:** Checks for large size differences between variants on
-/// `enum`s.
-///
-/// **Why is this bad?** Enum size is bounded by the largest variant. Having a
-/// large variant
-/// can penalize the memory layout of that enum.
-///
-/// **Known problems:** None.
-///
-/// **Example:**
-/// ```rust
-/// enum Test {
-///    A(i32),
-///    B([i32; 8000]),
-/// }
-/// ```
 declare_clippy_lint! {
+    /// **What it does:** Checks for large size differences between variants on
+    /// `enum`s.
+    ///
+    /// **Why is this bad?** Enum size is bounded by the largest variant. Having a
+    /// large variant
+    /// can penalize the memory layout of that enum.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust
+    /// enum Test {
+    ///     A(i32),
+    ///     B([i32; 8000]),
+    /// }
+    /// ```
     pub LARGE_ENUM_VARIANT,
     perf,
     "large size difference between variants on an enum"
@@ -45,6 +35,7 @@ pub struct LargeEnumVariant {
 }
 
 impl LargeEnumVariant {
+    #[must_use]
     pub fn new(maximum_size_difference_allowed: u64) -> Self {
         Self {
             maximum_size_difference_allowed,
@@ -52,19 +43,14 @@ pub fn new(maximum_size_difference_allowed: u64) -> Self {
     }
 }
 
-impl LintPass for LargeEnumVariant {
-    fn get_lints(&self) -> LintArray {
-        lint_array!(LARGE_ENUM_VARIANT)
-    }
-}
+impl_lint_pass!(LargeEnumVariant => [LARGE_ENUM_VARIANT]);
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant {
-    fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &Item) {
-        let did = cx.tcx.hir.local_def_id(item.id);
-        if let ItemKind::Enum(ref def, _) = item.node {
+    fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &Item<'_>) {
+        let did = cx.tcx.hir().local_def_id(item.hir_id);
+        if let ItemKind::Enum(ref def, _) = item.kind {
             let ty = cx.tcx.type_of(did);
-            let adt = ty.ty_adt_def()
-                .expect("already checked whether this is an enum");
+            let adt = ty.ty_adt_def().expect("already checked whether this is an enum");
 
             let mut smallest_variant: Option<(_, _)> = None;
             let mut largest_variant: Option<(_, _)> = None;
@@ -100,14 +86,14 @@ fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &Item) {
                         "large size difference between variants",
                         |db| {
                             if variant.fields.len() == 1 {
-                                let span = match def.variants[i].node.data {
-                                    VariantData::Struct(ref fields, _) | VariantData::Tuple(ref fields, _) => {
+                                let span = match def.variants[i].data {
+                                    VariantData::Struct(ref fields, ..) | VariantData::Tuple(ref fields, ..) => {
                                         fields[0].ty.span
                                     },
-                                    VariantData::Unit(_) => unreachable!(),
+                                    VariantData::Unit(..) => unreachable!(),
                                 };
                                 if let Some(snip) = snippet_opt(cx, span) {
-                                    db.span_suggestion_with_applicability(
+                                    db.span_suggestion(
                                         span,
                                         "consider boxing the large fields to reduce the total size of the \
                                          enum",