refactor: extract common pat_is_wild to clippy_utils

This function was previously defined for the iter_kv_map,
for_kw_map, and unused_enumerate_index lints. This commit extracts
it into clippy_utils.

Author: dnbln

clippy_lints/src/loops/for_kv_map.rs

@@ -1,9 +1,8 @@
 use super::FOR_KV_MAP;
 use clippy_utils::diagnostics::{multispan_sugg, span_lint_and_then};
 use clippy_utils::source::snippet;
-use clippy_utils::sugg;
 use clippy_utils::ty::is_type_diagnostic_item;
-use clippy_utils::visitors::is_local_used;
+use clippy_utils::{pat_is_wild, sugg};
 use rustc_hir::{BorrowKind, Expr, ExprKind, Mutability, Pat, PatKind};
 use rustc_lint::LateContext;
 use rustc_middle::ty;
@@ -55,12 +54,3 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>, arg: &'tcx
         }
     }
 }
-
-/// Returns `true` if the pattern is a `PatWild` or an ident prefixed with `_`.
-fn pat_is_wild<'tcx>(cx: &LateContext<'tcx>, pat: &'tcx PatKind<'_>, body: &'tcx Expr<'_>) -> bool {
-    match *pat {
-        PatKind::Wild => true,
-        PatKind::Binding(_, id, ident, None) if ident.as_str().starts_with('_') => !is_local_used(cx, body, id),
-        _ => false,
-    }
-}

clippy_lints/src/loops/unused_enumerate_index.rs

@@ -1,8 +1,7 @@
 use super::UNUSED_ENUMERATE_INDEX;
 use clippy_utils::diagnostics::{multispan_sugg, span_lint_and_then};
 use clippy_utils::source::snippet;
-use clippy_utils::sugg;
-use clippy_utils::visitors::is_local_used;
+use clippy_utils::{pat_is_wild, sugg};
 use rustc_hir::def::DefKind;
 use rustc_hir::{Expr, ExprKind, Pat, PatKind};
 use rustc_lint::LateContext;
@@ -61,12 +60,3 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>, arg: &'tcx
         },
     );
 }
-
-/// Returns `true` if the pattern is a `PatWild` or an ident prefixed with `_`.
-fn pat_is_wild<'tcx>(cx: &LateContext<'tcx>, pat: &'tcx PatKind<'_>, body: &'tcx Expr<'_>) -> bool {
-    match *pat {
-        PatKind::Wild => true,
-        PatKind::Binding(_, id, ident, None) if ident.as_str().starts_with('_') => !is_local_used(cx, body, id),
-        _ => false,
-    }
-}

clippy_lints/src/methods/iter_kv_map.rs

@@ -3,9 +3,8 @@
 use super::ITER_KV_MAP;
 use clippy_utils::diagnostics::{multispan_sugg, span_lint_and_sugg, span_lint_and_then};
 use clippy_utils::source::{snippet, snippet_with_applicability};
-use clippy_utils::sugg;
 use clippy_utils::ty::is_type_diagnostic_item;
-use clippy_utils::visitors::is_local_used;
+use clippy_utils::{pat_is_wild, sugg};
 use rustc_hir::{BindingAnnotation, Body, BorrowKind, ByRef, Expr, ExprKind, Mutability, Pat, PatKind};
 use rustc_lint::{LateContext, LintContext};
 use rustc_middle::ty;
@@ -84,13 +83,3 @@ pub(super) fn check<'tcx>(
         }
     }
 }
-
-/// Returns `true` if the pattern is a `PatWild`, or is an ident prefixed with `_`
-/// that is not locally used.
-fn pat_is_wild<'tcx>(cx: &LateContext<'tcx>, pat: &'tcx PatKind<'_>, body: &'tcx Expr<'_>) -> bool {
-    match *pat {
-        PatKind::Wild => true,
-        PatKind::Binding(_, id, ident, None) if ident.as_str().starts_with('_') => !is_local_used(cx, body, id),
-        _ => false,
-    }
-}

clippy_utils/src/lib.rs

@@ -2960,3 +2960,15 @@ op_utils! {
     Shl    ShlAssign
     Shr    ShrAssign
 }
+
+/// Returns `true` if the pattern is a `PatWild`, or is an ident prefixed with `_`
+/// that is not locally used.
+pub fn pat_is_wild<'tcx>(cx: &LateContext<'tcx>, pat: &'tcx PatKind<'_>, body: impl Visitable<'tcx>) -> bool {
+    match *pat {
+        PatKind::Wild => true,
+        PatKind::Binding(_, id, ident, None) if ident.as_str().starts_with('_') => {
+            !visitors::is_local_used(cx, body, id)
+        },
+        _ => false,
+    }
+}