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Auto merge of #8226 - Jarcho:manual_memcpy_8160, r=flip1995

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`manual_memcpy` fix

fixes #8160

Ideally this would work with `VecDeque`, but the current interface is unsuitable for it. At a minimum something like `range_as_slices` would be needed.

changelog: Don't lint `manual_memcpy` on `VecDeque`
changelog: Suggest `copy_from_slice` for `manual_memcpy` when applicable
This commit is contained in:
bors
2022-01-12 18:44:34 +00:00
parent 5479024250 062db10c12
commit 60e68d68c6
4 changed files with 58 additions and 40 deletions
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35
clippy_lints/src/loops/manual_memcpy.rs
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@@ -2,7 +2,7 @@ use super::{IncrementVisitor, InitializeVisitor, MANUAL_MEMCPY};
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet;
use clippy_utils::sugg::Sugg;
use clippy_utils::ty::is_type_diagnostic_item;
use clippy_utils::ty::is_copy;
use clippy_utils::{get_enclosing_block, higher, path_to_local, sugg};
use if_chain::if_chain;
use rustc_ast::ast;
@@ -62,15 +62,15 @@ pub(super) fn check<'tcx>(
if_chain! {
if let ExprKind::Index(base_left, idx_left) = lhs.kind;
if let ExprKind::Index(base_right, idx_right) = rhs.kind;
if is_slice_like(cx, cx.typeck_results().expr_ty(base_left));
if is_slice_like(cx, cx.typeck_results().expr_ty(base_right));
if let Some(ty) = get_slice_like_element_ty(cx, cx.typeck_results().expr_ty(base_left));
if get_slice_like_element_ty(cx, cx.typeck_results().expr_ty(base_right)).is_some();
if let Some((start_left, offset_left)) = get_details_from_idx(cx, idx_left, &starts);
if let Some((start_right, offset_right)) = get_details_from_idx(cx, idx_right, &starts);
// Source and destination must be different
if path_to_local(base_left) != path_to_local(base_right);
then {
Some((IndexExpr { base: base_left, idx: start_left, idx_offset: offset_left },
Some((ty, IndexExpr { base: base_left, idx: start_left, idx_offset: offset_left },
IndexExpr { base: base_right, idx: start_right, idx_offset: offset_right }))
} else {
None
@@ -78,7 +78,7 @@ pub(super) fn check<'tcx>(
}
})
})
.map(|o| o.map(|(dst, src)| build_manual_memcpy_suggestion(cx, start, end, limits, &dst, &src)))
.map(|o| o.map(|(ty, dst, src)| build_manual_memcpy_suggestion(cx, start, end, limits, ty, &dst, &src)))
.collect::<Option<Vec<_>>>()
.filter(|v| !v.is_empty())
.map(|v| v.join("\n "));
@@ -105,6 +105,7 @@ fn build_manual_memcpy_suggestion<'tcx>(
start: &Expr<'_>,
end: &Expr<'_>,
limits: ast::RangeLimits,
elem_ty: Ty<'tcx>,
dst: &IndexExpr<'_>,
src: &IndexExpr<'_>,
) -> String {
@@ -187,9 +188,16 @@ fn build_manual_memcpy_suggestion<'tcx>(
.into()
};
let method_str = if is_copy(cx, elem_ty) {
"copy_from_slice"
} else {
"clone_from_slice"
};
format!(
"{}.clone_from_slice(&{}[{}..{}]);",
"{}.{}(&{}[{}..{}]);",
dst,
method_str,
src_base_str,
src_offset.maybe_par(),
src_limit.maybe_par()
@@ -324,14 +332,13 @@ struct Start<'hir> {
kind: StartKind<'hir>,
}
fn is_slice_like<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'_>) -> bool {
let is_slice = match ty.kind() {
ty::Ref(_, subty, _) => is_slice_like(cx, subty),
ty::Slice(..) | ty::Array(..) => true,
_ => false,
};
is_slice || is_type_diagnostic_item(cx, ty, sym::Vec) || is_type_diagnostic_item(cx, ty, sym::VecDeque)
fn get_slice_like_element_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'tcx>> {
match ty.kind() {
ty::Adt(adt, subs) if cx.tcx.is_diagnostic_item(sym::Vec, adt.did) => Some(subs.type_at(0)),
ty::Ref(_, subty, _) => get_slice_like_element_ty(cx, subty),
ty::Slice(ty) | ty::Array(ty, _) => Some(ty),
_ => None,
}
}
fn fetch_cloned_expr<'tcx>(expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {