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Suggest copy_from_slice for manual_memcpy when possible

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This commit is contained in:
Jason Newcomb 2022-01-05 12:35:35 -05:00
parent 14f34454b0
commit 3925def9cf
3 changed files with 44 additions and 35 deletions
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29
clippy_lints/src/loops/manual_memcpy.rs
View file

@ -2,6 +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_copy;
use clippy_utils::{get_enclosing_block, higher, path_to_local, sugg};
use if_chain::if_chain;
use rustc_ast::ast;
@ -61,15 +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
@ -77,7 +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 "));
@ -104,6 +105,7 @@ fn build_manual_memcpy_suggestion<'tcx>(
start: &Expr<'_>,
end: &Expr<'_>,
limits: ast::RangeLimits,
elem_ty: Ty<'tcx>,
dst: &IndexExpr<'_>,
src: &IndexExpr<'_>,
) -> String {
@ -186,9 +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()
@ -323,12 +332,12 @@ struct Start<'hir> {
kind: StartKind<'hir>,
}
fn is_slice_like<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'_>) -> bool {
fn get_slice_like_element_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'tcx>> {
match ty.kind() {
ty::Adt(adt, _) => cx.tcx.is_diagnostic_item(sym::Vec, adt.did),
ty::Ref(_, subty, _) => is_slice_like(cx, subty),
ty::Slice(..) | ty::Array(..) => true,
_ => false,
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,
}
}

24
tests/ui/manual_memcpy/with_loop_counters.stderr
View file

@ -5,7 +5,7 @@ LL | / for i in 3..src.len() {
LL | | dst[i] = src[count];
LL | | count += 1;
LL | | }
| |_____^ help: try replacing the loop by: `dst[3..src.len()].clone_from_slice(&src[..(src.len() - 3)]);`
| |_____^ help: try replacing the loop by: `dst[3..src.len()].copy_from_slice(&src[..(src.len() - 3)]);`
|
= note: `-D clippy::manual-memcpy` implied by `-D warnings`
@ -16,7 +16,7 @@ LL | / for i in 3..src.len() {
LL | | dst[count] = src[i];
LL | | count += 1;
LL | | }
| |_____^ help: try replacing the loop by: `dst[..(src.len() - 3)].clone_from_slice(&src[3..]);`
| |_____^ help: try replacing the loop by: `dst[..(src.len() - 3)].copy_from_slice(&src[3..]);`
error: it looks like you're manually copying between slices
--> $DIR/with_loop_counters.rs:17:5
@ -25,7 +25,7 @@ LL | / for i in 0..src.len() {
LL | | dst[count] = src[i];
LL | | count += 1;
LL | | }
| |_____^ help: try replacing the loop by: `dst[3..(src.len() + 3)].clone_from_slice(&src[..]);`
| |_____^ help: try replacing the loop by: `dst[3..(src.len() + 3)].copy_from_slice(&src[..]);`
error: it looks like you're manually copying between slices
--> $DIR/with_loop_counters.rs:23:5
@ -34,7 +34,7 @@ LL | / for i in 0..src.len() {
LL | | dst[i] = src[count];
LL | | count += 1;
LL | | }
| |_____^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[3..(src.len() + 3)]);`
| |_____^ help: try replacing the loop by: `dst[..src.len()].copy_from_slice(&src[3..(src.len() + 3)]);`
error: it looks like you're manually copying between slices
--> $DIR/with_loop_counters.rs:29:5
@ -43,7 +43,7 @@ LL | / for i in 3..(3 + src.len()) {
LL | | dst[i] = src[count];
LL | | count += 1;
LL | | }
| |_____^ help: try replacing the loop by: `dst[3..(3 + src.len())].clone_from_slice(&src[..(3 + src.len() - 3)]);`
| |_____^ help: try replacing the loop by: `dst[3..(3 + src.len())].copy_from_slice(&src[..(3 + src.len() - 3)]);`
error: it looks like you're manually copying between slices
--> $DIR/with_loop_counters.rs:35:5
@ -52,7 +52,7 @@ LL | / for i in 5..src.len() {
LL | | dst[i] = src[count - 2];
LL | | count += 1;
LL | | }
| |_____^ help: try replacing the loop by: `dst[5..src.len()].clone_from_slice(&src[(3 - 2)..((src.len() - 2) + 3 - 5)]);`
| |_____^ help: try replacing the loop by: `dst[5..src.len()].copy_from_slice(&src[(3 - 2)..((src.len() - 2) + 3 - 5)]);`
error: it looks like you're manually copying between slices
--> $DIR/with_loop_counters.rs:41:5
@ -61,7 +61,7 @@ LL | / for i in 0..dst.len() {
LL | | dst[i] = src[count];
LL | | count += 1;
LL | | }
| |_____^ help: try replacing the loop by: `dst.clone_from_slice(&src[2..(dst.len() + 2)]);`
| |_____^ help: try replacing the loop by: `dst.copy_from_slice(&src[2..(dst.len() + 2)]);`
error: it looks like you're manually copying between slices
--> $DIR/with_loop_counters.rs:47:5
@ -70,7 +70,7 @@ LL | / for i in 3..10 {
LL | | dst[i] = src[count];
LL | | count += 1;
LL | | }
| |_____^ help: try replacing the loop by: `dst[3..10].clone_from_slice(&src[5..(10 + 5 - 3)]);`
| |_____^ help: try replacing the loop by: `dst[3..10].copy_from_slice(&src[5..(10 + 5 - 3)]);`
error: it looks like you're manually copying between slices
--> $DIR/with_loop_counters.rs:54:5
@ -85,8 +85,8 @@ LL | | }
|
help: try replacing the loop by
|
LL ~ dst[3..(src.len() + 3)].clone_from_slice(&src[..]);
LL + dst2[30..(src.len() + 30)].clone_from_slice(&src[..]);
LL ~ dst[3..(src.len() + 3)].copy_from_slice(&src[..]);
LL + dst2[30..(src.len() + 30)].copy_from_slice(&src[..]);
|
error: it looks like you're manually copying between slices
@ -96,7 +96,7 @@ LL | / for i in 0..1 << 1 {
LL | | dst[count] = src[i + 2];
LL | | count += 1;
LL | | }
| |_____^ help: try replacing the loop by: `dst[(0 << 1)..((1 << 1) + (0 << 1))].clone_from_slice(&src[2..((1 << 1) + 2)]);`
| |_____^ help: try replacing the loop by: `dst[(0 << 1)..((1 << 1) + (0 << 1))].copy_from_slice(&src[2..((1 << 1) + 2)]);`
error: it looks like you're manually copying between slices
--> $DIR/with_loop_counters.rs:71:5
@ -105,7 +105,7 @@ LL | / for i in 3..src.len() {
LL | | dst[i] = src[count];
LL | | count += 1
LL | | }
| |_____^ help: try replacing the loop by: `dst[3..src.len()].clone_from_slice(&src[..(src.len() - 3)]);`
| |_____^ help: try replacing the loop by: `dst[3..src.len()].copy_from_slice(&src[..(src.len() - 3)]);`
error: aborting due to 11 previous errors

26
tests/ui/manual_memcpy/without_loop_counters.stderr
View file

@ -4,7 +4,7 @@ error: it looks like you're manually copying between slices
LL | / for i in 0..src.len() {
LL | | dst[i] = src[i];
LL | | }
| |_____^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[..]);`
| |_____^ help: try replacing the loop by: `dst[..src.len()].copy_from_slice(&src[..]);`
|
= note: `-D clippy::manual-memcpy` implied by `-D warnings`
@ -14,7 +14,7 @@ error: it looks like you're manually copying between slices
LL | / for i in 0..src.len() {
LL | | dst[i + 10] = src[i];
LL | | }
| |_____^ help: try replacing the loop by: `dst[10..(src.len() + 10)].clone_from_slice(&src[..]);`
| |_____^ help: try replacing the loop by: `dst[10..(src.len() + 10)].copy_from_slice(&src[..]);`
error: it looks like you're manually copying between slices
--> $DIR/without_loop_counters.rs:17:5
@ -22,7 +22,7 @@ error: it looks like you're manually copying between slices
LL | / for i in 0..src.len() {
LL | | dst[i] = src[i + 10];
LL | | }
| |_____^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[10..(src.len() + 10)]);`
| |_____^ help: try replacing the loop by: `dst[..src.len()].copy_from_slice(&src[10..(src.len() + 10)]);`
error: it looks like you're manually copying between slices
--> $DIR/without_loop_counters.rs:22:5
@ -30,7 +30,7 @@ error: it looks like you're manually copying between slices
LL | / for i in 11..src.len() {
LL | | dst[i] = src[i - 10];
LL | | }
| |_____^ help: try replacing the loop by: `dst[11..src.len()].clone_from_slice(&src[(11 - 10)..(src.len() - 10)]);`
| |_____^ help: try replacing the loop by: `dst[11..src.len()].copy_from_slice(&src[(11 - 10)..(src.len() - 10)]);`
error: it looks like you're manually copying between slices
--> $DIR/without_loop_counters.rs:27:5
@ -38,7 +38,7 @@ error: it looks like you're manually copying between slices
LL | / for i in 0..dst.len() {
LL | | dst[i] = src[i];
LL | | }
| |_____^ help: try replacing the loop by: `dst.clone_from_slice(&src[..dst.len()]);`
| |_____^ help: try replacing the loop by: `dst.copy_from_slice(&src[..dst.len()]);`
error: it looks like you're manually copying between slices
--> $DIR/without_loop_counters.rs:40:5
@ -51,8 +51,8 @@ LL | | }
|
help: try replacing the loop by
|
LL ~ dst[10..256].clone_from_slice(&src[(10 - 5)..(256 - 5)]);
LL + dst2[(10 + 500)..(256 + 500)].clone_from_slice(&src[10..256]);
LL ~ dst[10..256].copy_from_slice(&src[(10 - 5)..(256 - 5)]);
LL + dst2[(10 + 500)..(256 + 500)].copy_from_slice(&src[10..256]);
|
error: it looks like you're manually copying between slices
@ -61,7 +61,7 @@ error: it looks like you're manually copying between slices
LL | / for i in 10..LOOP_OFFSET {
LL | | dst[i + LOOP_OFFSET] = src[i - some_var];
LL | | }
| |_____^ help: try replacing the loop by: `dst[(10 + LOOP_OFFSET)..(LOOP_OFFSET + LOOP_OFFSET)].clone_from_slice(&src[(10 - some_var)..(LOOP_OFFSET - some_var)]);`
| |_____^ help: try replacing the loop by: `dst[(10 + LOOP_OFFSET)..(LOOP_OFFSET + LOOP_OFFSET)].copy_from_slice(&src[(10 - some_var)..(LOOP_OFFSET - some_var)]);`
error: it looks like you're manually copying between slices
--> $DIR/without_loop_counters.rs:65:5
@ -69,7 +69,7 @@ error: it looks like you're manually copying between slices
LL | / for i in 0..src_vec.len() {
LL | | dst_vec[i] = src_vec[i];
LL | | }
| |_____^ help: try replacing the loop by: `dst_vec[..src_vec.len()].clone_from_slice(&src_vec[..]);`
| |_____^ help: try replacing the loop by: `dst_vec[..src_vec.len()].copy_from_slice(&src_vec[..]);`
error: it looks like you're manually copying between slices
--> $DIR/without_loop_counters.rs:94:5
@ -77,7 +77,7 @@ error: it looks like you're manually copying between slices
LL | / for i in from..from + src.len() {
LL | | dst[i] = src[i - from];
LL | | }
| |_____^ help: try replacing the loop by: `dst[from..(from + src.len())].clone_from_slice(&src[..(from + src.len() - from)]);`
| |_____^ help: try replacing the loop by: `dst[from..(from + src.len())].copy_from_slice(&src[..(from + src.len() - from)]);`
error: it looks like you're manually copying between slices
--> $DIR/without_loop_counters.rs:98:5
@ -85,7 +85,7 @@ error: it looks like you're manually copying between slices
LL | / for i in from..from + 3 {
LL | | dst[i] = src[i - from];
LL | | }
| |_____^ help: try replacing the loop by: `dst[from..(from + 3)].clone_from_slice(&src[..(from + 3 - from)]);`
| |_____^ help: try replacing the loop by: `dst[from..(from + 3)].copy_from_slice(&src[..(from + 3 - from)]);`
error: it looks like you're manually copying between slices
--> $DIR/without_loop_counters.rs:103:5
@ -93,7 +93,7 @@ error: it looks like you're manually copying between slices
LL | / for i in 0..5 {
LL | | dst[i - 0] = src[i];
LL | | }
| |_____^ help: try replacing the loop by: `dst[..5].clone_from_slice(&src[..5]);`
| |_____^ help: try replacing the loop by: `dst[..5].copy_from_slice(&src[..5]);`
error: it looks like you're manually copying between slices
--> $DIR/without_loop_counters.rs:108:5
@ -101,7 +101,7 @@ error: it looks like you're manually copying between slices
LL | / for i in 0..0 {
LL | | dst[i] = src[i];
LL | | }
| |_____^ help: try replacing the loop by: `dst[..0].clone_from_slice(&src[..0]);`
| |_____^ help: try replacing the loop by: `dst[..0].copy_from_slice(&src[..0]);`
error: it looks like you're manually copying between slices
--> $DIR/without_loop_counters.rs:120:5