diff options
| -rw-r--r-- | clippy_lints/src/ranges.rs | 62 | ||||
| -rw-r--r-- | tests/ui/reversed_empty_ranges_fixable.fixed | 8 | ||||
| -rw-r--r-- | tests/ui/reversed_empty_ranges_fixable.rs | 8 | ||||
| -rw-r--r-- | tests/ui/reversed_empty_ranges_fixable.stderr | 16 | ||||
| -rw-r--r-- | tests/ui/reversed_empty_ranges_unfixable.rs | 5 | ||||
| -rw-r--r-- | tests/ui/reversed_empty_ranges_unfixable.stderr | 18 |
6 files changed, 51 insertions, 66 deletions
diff --git a/clippy_lints/src/ranges.rs b/clippy_lints/src/ranges.rs index 1eb26d97ed4..52e540d4e00 100644 --- a/clippy_lints/src/ranges.rs +++ b/clippy_lints/src/ranges.rs @@ -241,14 +241,26 @@ fn check_inclusive_range_minus_one(cx: &LateContext<'_, '_>, expr: &Expr<'_>) { } fn check_reversed_empty_range(cx: &LateContext<'_, '_>, expr: &Expr<'_>) { - fn inside_indexing_expr<'a>(cx: &'a LateContext<'_, '_>, expr: &Expr<'_>) -> Option<&'a Expr<'a>> { - match get_parent_expr(cx, expr) { - parent_expr @ Some(Expr { + fn inside_indexing_expr(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool { + matches!( + get_parent_expr(cx, expr), + Some(Expr { kind: ExprKind::Index(..), .. - }) => parent_expr, - _ => None, + }) + ) + } + + fn is_for_loop_arg(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool { + let mut cur_expr = expr; + while let Some(parent_expr) = get_parent_expr(cx, cur_expr) { + match higher::for_loop(parent_expr) { + Some((_, args, _)) if args.hir_id == expr.hir_id => return true, + _ => cur_expr = parent_expr, + } } + + false } fn is_empty_range(limits: RangeLimits, ordering: Ordering) -> bool { @@ -267,34 +279,18 @@ fn check_reversed_empty_range(cx: &LateContext<'_, '_>, expr: &Expr<'_>) { if let Some(ordering) = Constant::partial_cmp(cx.tcx, ty, &start_idx, &end_idx); if is_empty_range(limits, ordering); then { - if let Some(parent_expr) = inside_indexing_expr(cx, expr) { - let (reason, outcome) = if ordering == Ordering::Equal { - ("empty", "always yield an empty slice") - } else { - ("reversed", "panic at run-time") - }; - - span_lint_and_then( - cx, - REVERSED_EMPTY_RANGES, - expr.span, - &format!("this range is {} and using it to index a slice will {}", reason, outcome), - |diag| { - if_chain! { - if ordering == Ordering::Equal; - if let ty::Slice(slice_ty) = cx.tables.expr_ty(parent_expr).kind; - then { - diag.span_suggestion( - parent_expr.span, - "if you want an empty slice, use", - format!("[] as &[{}]", slice_ty), - Applicability::MaybeIncorrect - ); - } - } - } - ); - } else { + if inside_indexing_expr(cx, expr) { + // Avoid linting `N..N` as it has proven to be useful, see #5689 and #5628 ... + if ordering != Ordering::Equal { + span_lint( + cx, + REVERSED_EMPTY_RANGES, + expr.span, + "this range is reversed and using it to index a slice will panic at run-time", + ); + } + // ... except in for loop arguments for backwards compatibility with `reverse_range_loop` + } else if ordering != Ordering::Equal || is_for_loop_arg(cx, expr) { span_lint_and_then( cx, REVERSED_EMPTY_RANGES, diff --git a/tests/ui/reversed_empty_ranges_fixable.fixed b/tests/ui/reversed_empty_ranges_fixable.fixed index 332c0427ef6..79e482eec30 100644 --- a/tests/ui/reversed_empty_ranges_fixable.fixed +++ b/tests/ui/reversed_empty_ranges_fixable.fixed @@ -4,8 +4,6 @@ const ANSWER: i32 = 42; fn main() { - let arr = [1, 2, 3, 4, 5]; - // These should be linted: (21..=42).rev().for_each(|x| println!("{}", x)); @@ -14,16 +12,18 @@ fn main() { for _ in (-42..=-21).rev() {} for _ in (21u32..42u32).rev() {} - let _ = &[] as &[i32]; - // These should be ignored as they are not empty ranges: (21..=42).for_each(|x| println!("{}", x)); (21..42).for_each(|x| println!("{}", x)); + let arr = [1, 2, 3, 4, 5]; let _ = &arr[1..=3]; let _ = &arr[1..3]; for _ in 21..=42 {} for _ in 21..42 {} + + // This range is empty but should be ignored, see issue #5689 + let _ = &arr[0..0]; } diff --git a/tests/ui/reversed_empty_ranges_fixable.rs b/tests/ui/reversed_empty_ranges_fixable.rs index 901ec8bcc09..b2e8bf33771 100644 --- a/tests/ui/reversed_empty_ranges_fixable.rs +++ b/tests/ui/reversed_empty_ranges_fixable.rs @@ -4,8 +4,6 @@ const ANSWER: i32 = 42; fn main() { - let arr = [1, 2, 3, 4, 5]; - // These should be linted: (42..=21).for_each(|x| println!("{}", x)); @@ -14,16 +12,18 @@ fn main() { for _ in -21..=-42 {} for _ in 42u32..21u32 {} - let _ = &arr[3..3]; - // These should be ignored as they are not empty ranges: (21..=42).for_each(|x| println!("{}", x)); (21..42).for_each(|x| println!("{}", x)); + let arr = [1, 2, 3, 4, 5]; let _ = &arr[1..=3]; let _ = &arr[1..3]; for _ in 21..=42 {} for _ in 21..42 {} + + // This range is empty but should be ignored, see issue #5689 + let _ = &arr[0..0]; } diff --git a/tests/ui/reversed_empty_ranges_fixable.stderr b/tests/ui/reversed_empty_ranges_fixable.stderr index 9a646fd9939..de83c4f3d63 100644 --- a/tests/ui/reversed_empty_ranges_fixable.stderr +++ b/tests/ui/reversed_empty_ranges_fixable.stderr @@ -1,5 +1,5 @@ error: this range is empty so it will yield no values - --> $DIR/reversed_empty_ranges_fixable.rs:11:5 + --> $DIR/reversed_empty_ranges_fixable.rs:9:5 | LL | (42..=21).for_each(|x| println!("{}", x)); | ^^^^^^^^^ @@ -11,7 +11,7 @@ LL | (21..=42).rev().for_each(|x| println!("{}", x)); | ^^^^^^^^^^^^^^^ error: this range is empty so it will yield no values - --> $DIR/reversed_empty_ranges_fixable.rs:12:13 + --> $DIR/reversed_empty_ranges_fixable.rs:10:13 | LL | let _ = (ANSWER..21).filter(|x| x % 2 == 0).take(10).collect::<Vec<_>>(); | ^^^^^^^^^^^^ @@ -22,7 +22,7 @@ LL | let _ = (21..ANSWER).rev().filter(|x| x % 2 == 0).take(10).collect::<Ve | ^^^^^^^^^^^^^^^^^^ error: this range is empty so it will yield no values - --> $DIR/reversed_empty_ranges_fixable.rs:14:14 + --> $DIR/reversed_empty_ranges_fixable.rs:12:14 | LL | for _ in -21..=-42 {} | ^^^^^^^^^ @@ -33,7 +33,7 @@ LL | for _ in (-42..=-21).rev() {} | ^^^^^^^^^^^^^^^^^ error: this range is empty so it will yield no values - --> $DIR/reversed_empty_ranges_fixable.rs:15:14 + --> $DIR/reversed_empty_ranges_fixable.rs:13:14 | LL | for _ in 42u32..21u32 {} | ^^^^^^^^^^^^ @@ -43,11 +43,5 @@ help: consider using the following if you are attempting to iterate over this ra LL | for _ in (21u32..42u32).rev() {} | ^^^^^^^^^^^^^^^^^^^^ -error: this range is empty and using it to index a slice will always yield an empty slice - --> $DIR/reversed_empty_ranges_fixable.rs:17:18 - | -LL | let _ = &arr[3..3]; - | ----^^^^- help: if you want an empty slice, use: `[] as &[i32]` - -error: aborting due to 5 previous errors +error: aborting due to 4 previous errors diff --git a/tests/ui/reversed_empty_ranges_unfixable.rs b/tests/ui/reversed_empty_ranges_unfixable.rs index 561a35625f0..264d3d1e95a 100644 --- a/tests/ui/reversed_empty_ranges_unfixable.rs +++ b/tests/ui/reversed_empty_ranges_unfixable.rs @@ -4,11 +4,12 @@ const ANSWER: i32 = 42; const SOME_NUM: usize = 3; fn main() { - let _ = (42 + 10..42 + 10).map(|x| x / 2).find(|&x| x == 21); - let arr = [1, 2, 3, 4, 5]; let _ = &arr[3usize..=1usize]; let _ = &arr[SOME_NUM..1]; for _ in ANSWER..ANSWER {} + + // Should not be linted, see issue #5689 + let _ = (42 + 10..42 + 10).map(|x| x / 2).find(|&x| x == 21); } diff --git a/tests/ui/reversed_empty_ranges_unfixable.stderr b/tests/ui/reversed_empty_ranges_unfixable.stderr index 240188cbb46..f23d4eb0f9c 100644 --- a/tests/ui/reversed_empty_ranges_unfixable.stderr +++ b/tests/ui/reversed_empty_ranges_unfixable.stderr @@ -1,28 +1,22 @@ -error: this range is empty so it will yield no values - --> $DIR/reversed_empty_ranges_unfixable.rs:7:13 - | -LL | let _ = (42 + 10..42 + 10).map(|x| x / 2).find(|&x| x == 21); - | ^^^^^^^^^^^^^^^^^^ - | - = note: `-D clippy::reversed-empty-ranges` implied by `-D warnings` - error: this range is reversed and using it to index a slice will panic at run-time - --> $DIR/reversed_empty_ranges_unfixable.rs:10:18 + --> $DIR/reversed_empty_ranges_unfixable.rs:8:18 | LL | let _ = &arr[3usize..=1usize]; | ^^^^^^^^^^^^^^^ + | + = note: `-D clippy::reversed-empty-ranges` implied by `-D warnings` error: this range is reversed and using it to index a slice will panic at run-time - --> $DIR/reversed_empty_ranges_unfixable.rs:11:18 + --> $DIR/reversed_empty_ranges_unfixable.rs:9:18 | LL | let _ = &arr[SOME_NUM..1]; | ^^^^^^^^^^^ error: this range is empty so it will yield no values - --> $DIR/reversed_empty_ranges_unfixable.rs:13:14 + --> $DIR/reversed_empty_ranges_unfixable.rs:11:14 | LL | for _ in ANSWER..ANSWER {} | ^^^^^^^^^^^^^^ -error: aborting due to 4 previous errors +error: aborting due to 3 previous errors |