use derefs_to_slice in methods/utils.rs

clippy_lints/src/methods/get_unwrap.rs

@@ -1,4 +1,4 @@
-use crate::methods::derefs_to_slice;
+use super::utils::derefs_to_slice;
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::ty::{is_type_diagnostic_item, match_type};

clippy_lints/src/methods/iter_cloned_collect.rs

@@ -1,4 +1,4 @@
-use crate::methods::derefs_to_slice;
+use crate::methods::utils::derefs_to_slice;
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::ty::is_type_diagnostic_item;
 use if_chain::if_chain;

clippy_lints/src/methods/iter_count.rs

@@ -1,4 +1,4 @@
-use crate::methods::derefs_to_slice;
+use super::utils::derefs_to_slice;
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::paths;
 use clippy_utils::source::snippet_with_applicability;

clippy_lints/src/methods/iter_next_slice.rs

@@ -1,4 +1,4 @@
-use crate::methods::derefs_to_slice;
+use crate::methods::utils::derefs_to_slice;
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::ty::is_type_diagnostic_item;

clippy_lints/src/methods/iter_nth.rs

@@ -1,7 +1,7 @@
-use crate::methods::derefs_to_slice;
 use crate::methods::iter_nth_zero;
 use clippy_utils::diagnostics::span_lint_and_help;
 use clippy_utils::ty::is_type_diagnostic_item;
+use crate::methods::utils::derefs_to_slice;
 use rustc_hir as hir;
 use rustc_lint::LateContext;
 use rustc_span::symbol::sym;

clippy_lints/src/methods/mod.rs

@@ -53,6 +53,7 @@ mod unnecessary_fold;
 mod unnecessary_lazy_eval;
 mod unwrap_used;
 mod useless_asref;
+mod utils;
 mod wrong_self_convention;
 mod zst_offset;
 
@@ -1976,47 +1977,6 @@ impl<'tcx> LateLintPass<'tcx> for Methods {
 
     extract_msrv_attr!(LateContext);
 }
-
-fn derefs_to_slice<'tcx>(
-    cx: &LateContext<'tcx>,
-    expr: &'tcx hir::Expr<'tcx>,
-    ty: Ty<'tcx>,
-) -> Option<&'tcx hir::Expr<'tcx>> {
-    fn may_slice<'a>(cx: &LateContext<'a>, ty: Ty<'a>) -> bool {
-        match ty.kind() {
-            ty::Slice(_) => true,
-            ty::Adt(def, _) if def.is_box() => may_slice(cx, ty.boxed_ty()),
-            ty::Adt(..) => is_type_diagnostic_item(cx, ty, sym::vec_type),
-            ty::Array(_, size) => size
-                .try_eval_usize(cx.tcx, cx.param_env)
-                .map_or(false, |size| size < 32),
-            ty::Ref(_, inner, _) => may_slice(cx, inner),
-            _ => false,
-        }
-    }
-
-    if let hir::ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind {
-        if path.ident.name == sym::iter && may_slice(cx, cx.typeck_results().expr_ty(&args[0])) {
-            Some(&args[0])
-        } else {
-            None
-        }
-    } else {
-        match ty.kind() {
-            ty::Slice(_) => Some(expr),
-            ty::Adt(def, _) if def.is_box() && may_slice(cx, ty.boxed_ty()) => Some(expr),
-            ty::Ref(_, inner, _) => {
-                if may_slice(cx, inner) {
-                    Some(expr)
-                } else {
-                    None
-                }
-            },
-            _ => None,
-        }
-    }
-}
-
 /// Used for `lint_binary_expr_with_method_call`.
 #[derive(Copy, Clone)]
 struct BinaryExprInfo<'a> {