Move adjust_derefs_manually_drop into clippy_utils

Author: samueltardieu

clippy_lints/src/dereference.rs

@@ -1,12 +1,11 @@
 use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_hir_and_then};
 use clippy_utils::source::{snippet_with_applicability, snippet_with_context};
 use clippy_utils::sugg::has_enclosing_paren;
-use clippy_utils::ty::{implements_trait, is_manually_drop};
+use clippy_utils::ty::{adjust_derefs_manually_drop, implements_trait, is_manually_drop};
 use clippy_utils::{
     DefinedTy, ExprUseNode, expr_use_ctxt, get_parent_expr, is_block_like, is_lint_allowed, path_to_local,
     peel_middle_ty_refs,
 };
-use core::mem;
 use rustc_ast::util::parser::ExprPrecedence;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_errors::Applicability;
@@ -707,14 +706,6 @@ fn try_parse_ref_op<'tcx>(
     ))
 }
 
-// Checks if the adjustments contains a deref of `ManuallyDrop<_>`
-fn adjust_derefs_manually_drop<'tcx>(adjustments: &'tcx [Adjustment<'tcx>], mut ty: Ty<'tcx>) -> bool {
-    adjustments.iter().any(|a| {
-        let ty = mem::replace(&mut ty, a.target);
-        matches!(a.kind, Adjust::Deref(Some(ref op)) if op.mutbl == Mutability::Mut) && is_manually_drop(ty)
-    })
-}
-
 // Checks whether the type for a deref call actually changed the type, not just the mutability of
 // the reference.
 fn deref_method_same_type<'tcx>(result_ty: Ty<'tcx>, arg_ty: Ty<'tcx>) -> bool {

clippy_utils/src/ty/mod.rs

@@ -17,6 +17,7 @@ use rustc_lint::LateContext;
 use rustc_middle::mir::ConstValue;
 use rustc_middle::mir::interpret::Scalar;
 use rustc_middle::traits::EvaluationResult;
+use rustc_middle::ty::adjustment::{Adjust, Adjustment};
 use rustc_middle::ty::layout::ValidityRequirement;
 use rustc_middle::ty::{
     self, AdtDef, AliasTy, AssocItem, AssocTag, Binder, BoundRegion, FnSig, GenericArg, GenericArgKind, GenericArgsRef,
@@ -30,7 +31,7 @@ use rustc_trait_selection::traits::query::normalize::QueryNormalizeExt;
 use rustc_trait_selection::traits::{Obligation, ObligationCause};
 use std::assert_matches::debug_assert_matches;
 use std::collections::hash_map::Entry;
-use std::iter;
+use std::{iter, mem};
 
 use crate::path_res;
 use crate::paths::{PathNS, lookup_path_str};
@@ -1362,7 +1363,6 @@ pub fn is_slice_like<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
         || matches!(ty.kind(), ty::Adt(adt_def, _) if cx.tcx.is_diagnostic_item(sym::Vec, adt_def.did()))
 }
 
-/// Gets the index of a field by name.
 pub fn get_field_idx_by_name(ty: Ty<'_>, name: Symbol) -> Option<usize> {
     match *ty.kind() {
         ty::Adt(def, _) if def.is_union() || def.is_struct() => {
@@ -1372,3 +1372,11 @@ pub fn get_field_idx_by_name(ty: Ty<'_>, name: Symbol) -> Option<usize> {
         _ => None,
     }
 }
+
+/// Checks if the adjustments contain a mutable dereference of a `ManuallyDrop<_>`.
+pub fn adjust_derefs_manually_drop<'tcx>(adjustments: &'tcx [Adjustment<'tcx>], mut ty: Ty<'tcx>) -> bool {
+    adjustments.iter().any(|a| {
+        let ty = mem::replace(&mut ty, a.target);
+        matches!(a.kind, Adjust::Deref(Some(op)) if op.mutbl == Mutability::Mut) && is_manually_drop(ty)
+    })
+}