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Fix lint manual_slice_size_calculation when the slice is ref more than once

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This commit is contained in:
coekjan 2024-10-02 23:51:52 +08:00
parent 398be8c842
commit 2080634d33
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GPG Key ID: E2B19491B838BB2B
4 changed files with 35 additions and 13 deletions
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14
clippy_lints/src/manual_slice_size_calculation.rs
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@ -45,10 +45,11 @@ impl<'tcx> LateLintPass<'tcx> for ManualSliceSizeCalculation {
&& !expr.span.from_expansion()
// Does not apply inside const because size_of_val is not cost in stable.
&& !is_in_const_context(cx)
&& let Some(receiver) = simplify(cx, left, right)
&& let Some((receiver, refs_count)) = simplify(cx, left, right)
{
let ctxt = expr.span.ctxt();
let mut app = Applicability::MachineApplicable;
let deref = "*".repeat(refs_count - 1);
let val_name = snippet_with_context(cx, receiver.span, ctxt, "slice", &mut app).0;
let Some(sugg) = std_or_core(cx) else { return };
@ -58,7 +59,7 @@ impl<'tcx> LateLintPass<'tcx> for ManualSliceSizeCalculation {
expr.span,
"manual slice size calculation",
"try",
format!("{sugg}::mem::size_of_val({val_name})"),
format!("{sugg}::mem::size_of_val({deref}{val_name})"),
app,
);
}
@ -69,7 +70,7 @@ fn simplify<'tcx>(
cx: &LateContext<'tcx>,
expr1: &'tcx Expr<'tcx>,
expr2: &'tcx Expr<'tcx>,
) -> Option<&'tcx Expr<'tcx>> {
) -> Option<(&'tcx Expr<'tcx>, usize)> {
let expr1 = expr_or_init(cx, expr1);
let expr2 = expr_or_init(cx, expr2);
@ -80,13 +81,14 @@ fn simplify_half<'tcx>(
cx: &LateContext<'tcx>,
expr1: &'tcx Expr<'tcx>,
expr2: &'tcx Expr<'tcx>,
) -> Option<&'tcx Expr<'tcx>> {
) -> Option<(&'tcx Expr<'tcx>, usize)> {
if !expr1.span.from_expansion()
// expr1 is `[T1].len()`?
&& let ExprKind::MethodCall(method_path, receiver, _, _) = expr1.kind
&& method_path.ident.name == sym::len
&& let receiver_ty = cx.typeck_results().expr_ty(receiver)
&& let ty::Slice(ty1) = receiver_ty.peel_refs().kind()
&& let (receiver_ty, refs_count) = clippy_utils::ty::walk_ptrs_ty_depth(receiver_ty)
&& let ty::Slice(ty1) = receiver_ty.kind()
// expr2 is `size_of::<T2>()`?
&& let ExprKind::Call(func, _) = expr2.kind
&& let ExprKind::Path(ref func_qpath) = func.kind
@ -96,7 +98,7 @@ fn simplify_half<'tcx>(
// T1 == T2?
&& *ty1 == ty2
{
Some(receiver)
Some((receiver, refs_count))
} else {
None
}

4
tests/ui/manual_slice_size_calculation.fixed
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@ -10,11 +10,15 @@ use proc_macros::external;
fn main() {
let v_i32 = Vec::<i32>::new();
let s_i32 = v_i32.as_slice();
let s_i32_ref = &s_i32;
let s_i32_ref_ref = &s_i32_ref;
// True positives:
let _ = std::mem::size_of_val(s_i32); // WARNING
let _ = std::mem::size_of_val(s_i32); // WARNING
let _ = std::mem::size_of_val(s_i32) * 5; // WARNING
let _ = std::mem::size_of_val(*s_i32_ref); // WARNING
let _ = std::mem::size_of_val(**s_i32_ref_ref); // WARNING
let len = s_i32.len();
let size = size_of::<i32>();

4
tests/ui/manual_slice_size_calculation.rs
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@ -10,11 +10,15 @@ use proc_macros::external;
fn main() {
let v_i32 = Vec::<i32>::new();
let s_i32 = v_i32.as_slice();
let s_i32_ref = &s_i32;
let s_i32_ref_ref = &s_i32_ref;
// True positives:
let _ = s_i32.len() * size_of::<i32>(); // WARNING
let _ = size_of::<i32>() * s_i32.len(); // WARNING
let _ = size_of::<i32>() * s_i32.len() * 5; // WARNING
let _ = size_of::<i32>() * s_i32_ref.len(); // WARNING
let _ = size_of::<i32>() * s_i32_ref_ref.len(); // WARNING
let len = s_i32.len();
let size = size_of::<i32>();

26
tests/ui/manual_slice_size_calculation.stderr
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@ -1,5 +1,5 @@
error: manual slice size calculation
--> tests/ui/manual_slice_size_calculation.rs:15:13
--> tests/ui/manual_slice_size_calculation.rs:17:13
|
LL | let _ = s_i32.len() * size_of::<i32>(); // WARNING
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`
@ -8,40 +8,52 @@ LL | let _ = s_i32.len() * size_of::<i32>(); // WARNING
= help: to override `-D warnings` add `#[allow(clippy::manual_slice_size_calculation)]`
error: manual slice size calculation
--> tests/ui/manual_slice_size_calculation.rs:16:13
--> tests/ui/manual_slice_size_calculation.rs:18:13
|
LL | let _ = size_of::<i32>() * s_i32.len(); // WARNING
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`
error: manual slice size calculation
--> tests/ui/manual_slice_size_calculation.rs:17:13
--> tests/ui/manual_slice_size_calculation.rs:19:13
|
LL | let _ = size_of::<i32>() * s_i32.len() * 5; // WARNING
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`
error: manual slice size calculation
--> tests/ui/manual_slice_size_calculation.rs:20:13
|
LL | let _ = size_of::<i32>() * s_i32_ref.len(); // WARNING
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(*s_i32_ref)`
error: manual slice size calculation
--> tests/ui/manual_slice_size_calculation.rs:21:13
|
LL | let _ = size_of::<i32>() * s_i32_ref_ref.len(); // WARNING
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(**s_i32_ref_ref)`
error: manual slice size calculation
--> tests/ui/manual_slice_size_calculation.rs:25:13
|
LL | let _ = len * size_of::<i32>(); // WARNING
| ^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`
error: manual slice size calculation
--> tests/ui/manual_slice_size_calculation.rs:22:13
--> tests/ui/manual_slice_size_calculation.rs:26:13
|
LL | let _ = s_i32.len() * size; // WARNING
| ^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`
error: manual slice size calculation
--> tests/ui/manual_slice_size_calculation.rs:23:13
--> tests/ui/manual_slice_size_calculation.rs:27:13
|
LL | let _ = len * size; // WARNING
| ^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`
error: manual slice size calculation
--> tests/ui/manual_slice_size_calculation.rs:25:13
--> tests/ui/manual_slice_size_calculation.rs:29:13
|
LL | let _ = external!(&[1u64][..]).len() * size_of::<u64>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(external!(&[1u64][..]))`
error: aborting due to 7 previous errors
error: aborting due to 9 previous errors