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Auto merge of rust-lang#8226 - Jarcho:manual_memcpy_8160, r=flip1995
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`manual_memcpy` fix

fixes rust-lang#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
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@bors
bors committed Jan 12, 2022
2 parents 5479024 + 062db10 commit 60e68d6
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Showing 4 changed files with 58 additions and 40 deletions.
35 changes: 21 additions & 14 deletions clippy_lints/src/loops/manual_memcpy.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -62,23 +62,23 @@ 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
}
}
})
})
.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 "));
Expand All @@ -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 {
Expand Down Expand Up @@ -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()
Expand Down Expand Up @@ -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> {
Expand Down
24 changes: 12 additions & 12 deletions tests/ui/manual_memcpy/with_loop_counters.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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`

Expand All @@ -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
Expand All @@ -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
Expand All @@ -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
Expand All @@ -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
Expand All @@ -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
Expand All @@ -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
Expand All @@ -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
Expand All @@ -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
Expand All @@ -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
Expand All @@ -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

11 changes: 11 additions & 0 deletions tests/ui/manual_memcpy/without_loop_counters.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -113,6 +113,17 @@ pub fn manual_copy(src: &[i32], dst: &mut [i32], dst2: &mut [i32]) {
for i in 0.. {
dst[i] = src[i];
}

// VecDeque - ideally this would work, but would require something like `range_as_slices`
let mut dst = std::collections::VecDeque::from_iter([0; 5]);
let src = std::collections::VecDeque::from_iter([0, 1, 2, 3, 4]);
for i in 0..dst.len() {
dst[i] = src[i];
}
let src = vec![0, 1, 2, 3, 4];
for i in 0..dst.len() {
dst[i] = src[i];
}
}

#[warn(clippy::needless_range_loop, clippy::manual_memcpy)]
Expand Down
28 changes: 14 additions & 14 deletions tests/ui/manual_memcpy/without_loop_counters.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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`

Expand All @@ -14,31 +14,31 @@ 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
|
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
|
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
|
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
Expand All @@ -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
Expand All @@ -61,50 +61,50 @@ 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
|
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
|
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
|
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
|
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
|
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
--> $DIR/without_loop_counters.rs:131:5
|
LL | / for i in 0..src.len() {
LL | | dst[i] = src[i].clone();
Expand Down

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