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merge XOR_SWAP with MANUAL_SWAP
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7 files changed

+175
-237
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7 files changed

+175
-237
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‎CHANGELOG.md‎

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2900,7 +2900,6 @@ Released 2018-09-13
29002900
[`wrong_pub_self_convention`]: https://rust-lang.github.io/rust-clippy/master/index.html#wrong_pub_self_convention
29012901
[`wrong_self_convention`]: https://rust-lang.github.io/rust-clippy/master/index.html#wrong_self_convention
29022902
[`wrong_transmute`]: https://rust-lang.github.io/rust-clippy/master/index.html#wrong_transmute
2903-
[`xor_swap`]: https://rust-lang.github.io/rust-clippy/master/index.html#xor_swap
29042903
[`zero_divided_by_zero`]: https://rust-lang.github.io/rust-clippy/master/index.html#zero_divided_by_zero
29052904
[`zero_prefixed_literal`]: https://rust-lang.github.io/rust-clippy/master/index.html#zero_prefixed_literal
29062905
[`zero_ptr`]: https://rust-lang.github.io/rust-clippy/master/index.html#zero_ptr

‎clippy_lints/src/lib.rs‎

Lines changed: 0 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -922,7 +922,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
922922
suspicious_trait_impl::SUSPICIOUS_OP_ASSIGN_IMPL,
923923
swap::ALMOST_SWAPPED,
924924
swap::MANUAL_SWAP,
925-
swap::XOR_SWAP,
926925
tabs_in_doc_comments::TABS_IN_DOC_COMMENTS,
927926
temporary_assignment::TEMPORARY_ASSIGNMENT,
928927
to_digit_is_some::TO_DIGIT_IS_SOME,
@@ -1420,7 +1419,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
14201419
LintId::of(suspicious_trait_impl::SUSPICIOUS_OP_ASSIGN_IMPL),
14211420
LintId::of(swap::ALMOST_SWAPPED),
14221421
LintId::of(swap::MANUAL_SWAP),
1423-
LintId::of(swap::XOR_SWAP),
14241422
LintId::of(tabs_in_doc_comments::TABS_IN_DOC_COMMENTS),
14251423
LintId::of(temporary_assignment::TEMPORARY_ASSIGNMENT),
14261424
LintId::of(to_digit_is_some::TO_DIGIT_IS_SOME),
@@ -1649,7 +1647,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
16491647
LintId::of(strings::STRING_FROM_UTF8_AS_BYTES),
16501648
LintId::of(strlen_on_c_strings::STRLEN_ON_C_STRINGS),
16511649
LintId::of(swap::MANUAL_SWAP),
1652-
LintId::of(swap::XOR_SWAP),
16531650
LintId::of(temporary_assignment::TEMPORARY_ASSIGNMENT),
16541651
LintId::of(transmute::CROSSPOINTER_TRANSMUTE),
16551652
LintId::of(transmute::TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS),

‎clippy_lints/src/swap.rs‎

Lines changed: 67 additions & 192 deletions
Original file line numberDiff line numberDiff line change
@@ -2,15 +2,15 @@ use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
22
use clippy_utils::source::snippet_with_applicability;
33
use clippy_utils::sugg::Sugg;
44
use clippy_utils::ty::is_type_diagnostic_item;
5-
use clippy_utils::{differing_macro_contexts, eq_expr_value};
5+
use clippy_utils::{can_mut_borrow_both, differing_macro_contexts, eq_expr_value};
66
use if_chain::if_chain;
77
use rustc_errors::Applicability;
88
use rustc_hir::{BinOpKind, Block, Expr, ExprKind, PatKind, QPath, Stmt, StmtKind};
99
use rustc_lint::{LateContext, LateLintPass};
1010
use rustc_middle::ty;
1111
use rustc_session::{declare_lint_pass, declare_tool_lint};
1212
use rustc_span::source_map::Spanned;
13-
use rustc_span::sym;
13+
use rustc_span::{sym, Span};
1414

1515
declare_clippy_lint! {
1616
/// ### What it does
@@ -65,37 +65,7 @@ declare_clippy_lint! {
6565
"`foo = bar; bar = foo` sequence"
6666
}
6767

68-
declare_clippy_lint! {
69-
/// **What it does:** Checks for uses of xor-based swaps.
70-
///
71-
/// **Why is this bad?** The `std::mem::swap` function exposes the intent better
72-
/// without deinitializing or copying either variable.
73-
///
74-
/// **Known problems:** None.
75-
///
76-
/// **Example:**
77-
///
78-
/// ```rust
79-
/// let mut a = 1;
80-
/// let mut b = 2;
81-
///
82-
/// a ^= b;
83-
/// b ^= a;
84-
/// a ^= b;
85-
/// ```
86-
///
87-
/// Use std::mem::swap() instead:
88-
/// ```rust
89-
/// let mut a = 1;
90-
/// let mut b = 2;
91-
/// std::mem::swap(&mut a, &mut b);
92-
/// ```
93-
pub XOR_SWAP,
94-
complexity,
95-
"xor-based swap of two variables"
96-
}
97-
98-
declare_lint_pass!(Swap => [MANUAL_SWAP, ALMOST_SWAPPED, XOR_SWAP]);
68+
declare_lint_pass!(Swap => [MANUAL_SWAP, ALMOST_SWAPPED]);
9969

10070
impl<'tcx> LateLintPass<'tcx> for Swap {
10171
fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx Block<'_>) {
@@ -105,6 +75,63 @@ impl<'tcx> LateLintPass<'tcx> for Swap {
10575
}
10676
}
10777

78+
fn generate_swap_warning(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>, span: Span, is_xor_based: bool) {
79+
let mut applicability = Applicability::MachineApplicable;
80+
81+
if !can_mut_borrow_both(cx, e1, e2) {
82+
if let ExprKind::Index(lhs1, idx1) = e1.kind {
83+
if let ExprKind::Index(lhs2, idx2) = e2.kind {
84+
if eq_expr_value(cx, lhs1, lhs2) {
85+
let ty = cx.typeck_results().expr_ty(lhs1).peel_refs();
86+
87+
if matches!(ty.kind(), ty::Slice(_))
88+
|| matches!(ty.kind(), ty::Array(_, _))
89+
|| is_type_diagnostic_item(cx, ty, sym::vec_type)
90+
|| is_type_diagnostic_item(cx, ty, sym::vecdeque_type)
91+
{
92+
let slice = Sugg::hir_with_applicability(cx, lhs1, "<slice>", &mut applicability);
93+
span_lint_and_sugg(
94+
cx,
95+
MANUAL_SWAP,
96+
span,
97+
&format!("this looks like you are swapping elements of `{}` manually", slice),
98+
"try",
99+
format!(
100+
"{}.swap({}, {})",
101+
slice.maybe_par(),
102+
snippet_with_applicability(cx, idx1.span, "..", &mut applicability),
103+
snippet_with_applicability(cx, idx2.span, "..", &mut applicability),
104+
),
105+
applicability,
106+
);
107+
}
108+
}
109+
}
110+
}
111+
return;
112+
}
113+
114+
let first = Sugg::hir_with_applicability(cx, e1, "..", &mut applicability);
115+
let second = Sugg::hir_with_applicability(cx, e2, "..", &mut applicability);
116+
span_lint_and_then(
117+
cx,
118+
MANUAL_SWAP,
119+
span,
120+
&format!("this looks like you are swapping `{}` and `{}` manually", first, second),
121+
|diag| {
122+
diag.span_suggestion(
123+
span,
124+
"try",
125+
format!("std::mem::swap({}, {})", first.mut_addr(), second.mut_addr()),
126+
applicability,
127+
);
128+
if !is_xor_based {
129+
diag.note("or maybe you should use `std::mem::replace`?");
130+
}
131+
},
132+
);
133+
}
134+
108135
/// Implementation of the `MANUAL_SWAP` lint.
109136
fn check_manual_swap(cx: &LateContext<'_>, block: &Block<'_>) {
110137
for w in block.stmts.windows(3) {
@@ -128,123 +155,13 @@ fn check_manual_swap(cx: &LateContext<'_>, block: &Block<'_>) {
128155
if eq_expr_value(cx, tmp_init, lhs1);
129156
if eq_expr_value(cx, rhs1, lhs2);
130157
then {
131-
if let ExprKind::Field(lhs1, _) = lhs1.kind {
132-
if let ExprKind::Field(lhs2, _) = lhs2.kind {
133-
if lhs1.hir_id.owner == lhs2.hir_id.owner {
134-
return;
135-
}
136-
}
137-
}
138-
139-
let mut applicability = Applicability::MachineApplicable;
140-
141-
let slice = check_for_slice(cx, lhs1, lhs2);
142-
let (replace, what, sugg) = if let Slice::NotSwappable = slice {
143-
return;
144-
} else if let Slice::Swappable(slice, idx1, idx2) = slice {
145-
if let Some(slice) = Sugg::hir_opt(cx, slice) {
146-
(
147-
false,
148-
format!(" elements of `{}`", slice),
149-
format!(
150-
"{}.swap({}, {})",
151-
slice.maybe_par(),
152-
snippet_with_applicability(cx, idx1.span, "..", &mut applicability),
153-
snippet_with_applicability(cx, idx2.span, "..", &mut applicability),
154-
),
155-
)
156-
} else {
157-
(false, String::new(), String::new())
158-
}
159-
} else if let (Some(first), Some(second)) = (Sugg::hir_opt(cx, lhs1), Sugg::hir_opt(cx, rhs1)) {
160-
(
161-
true,
162-
format!(" `{}` and `{}`", first, second),
163-
format!("std::mem::swap({}, {})", first.mut_addr(), second.mut_addr()),
164-
)
165-
} else {
166-
(true, String::new(), String::new())
167-
};
168-
169158
let span = w[0].span.to(second.span);
170-
171-
span_lint_and_then(
172-
cx,
173-
MANUAL_SWAP,
174-
span,
175-
&format!("this looks like you are swapping{} manually", what),
176-
|diag| {
177-
if !sugg.is_empty() {
178-
diag.span_suggestion(
179-
span,
180-
"try",
181-
sugg,
182-
applicability,
183-
);
184-
185-
if replace {
186-
diag.note("or maybe you should use `std::mem::replace`?");
187-
}
188-
}
189-
}
190-
);
159+
generate_swap_warning(cx, lhs1, lhs2, span, false);
191160
}
192161
}
193162
}
194163
}
195164

196-
enum Slice<'a> {
197-
/// `slice.swap(idx1, idx2)` can be used
198-
///
199-
/// ## Example
200-
///
201-
/// ```rust
202-
/// # let mut a = vec![0, 1];
203-
/// let t = a[1];
204-
/// a[1] = a[0];
205-
/// a[0] = t;
206-
/// // can be written as
207-
/// a.swap(0, 1);
208-
/// ```
209-
Swappable(&'a Expr<'a>, &'a Expr<'a>, &'a Expr<'a>),
210-
/// The `swap` function cannot be used.
211-
///
212-
/// ## Example
213-
///
214-
/// ```rust
215-
/// # let mut a = [vec![1, 2], vec![3, 4]];
216-
/// let t = a[0][1];
217-
/// a[0][1] = a[1][0];
218-
/// a[1][0] = t;
219-
/// ```
220-
NotSwappable,
221-
/// Not a slice
222-
None,
223-
}
224-
225-
/// Checks if both expressions are index operations into "slice-like" types.
226-
fn check_for_slice<'a>(cx: &LateContext<'_>, lhs1: &'a Expr<'_>, lhs2: &'a Expr<'_>) -> Slice<'a> {
227-
if let ExprKind::Index(lhs1, idx1) = lhs1.kind {
228-
if let ExprKind::Index(lhs2, idx2) = lhs2.kind {
229-
if eq_expr_value(cx, lhs1, lhs2) {
230-
let ty = cx.typeck_results().expr_ty(lhs1).peel_refs();
231-
232-
if matches!(ty.kind(), ty::Slice(_))
233-
|| matches!(ty.kind(), ty::Array(_, _))
234-
|| is_type_diagnostic_item(cx, ty, sym::vec_type)
235-
|| is_type_diagnostic_item(cx, ty, sym::vecdeque_type)
236-
{
237-
return Slice::Swappable(lhs1, idx1, idx2);
238-
}
239-
} else {
240-
return Slice::NotSwappable;
241-
}
242-
}
243-
}
244-
245-
Slice::None
246-
}
247-
248165
/// Implementation of the `ALMOST_SWAPPED` lint.
249166
fn check_suspicious_swap(cx: &LateContext<'_>, block: &Block<'_>) {
250167
for w in block.stmts.windows(2) {
@@ -295,62 +212,20 @@ fn check_suspicious_swap(cx: &LateContext<'_>, block: &Block<'_>) {
295212
}
296213
}
297214

298-
/// Implementation of the `XOR_SWAP` lint.
215+
/// Implementation of the xor case for `MANUAL_SWAP` lint.
299216
fn check_xor_swap(cx: &LateContext<'_>, block: &Block<'_>) {
300217
for window in block.stmts.windows(3) {
301218
if_chain! {
302219
if let Some((lhs0, rhs0)) = extract_sides_of_xor_assign(&window[0]);
303220
if let Some((lhs1, rhs1)) = extract_sides_of_xor_assign(&window[1]);
304221
if let Some((lhs2, rhs2)) = extract_sides_of_xor_assign(&window[2]);
305-
if eq_expr_value(cx, lhs0, rhs1)
306-
&& eq_expr_value(cx, rhs1, lhs2)
307-
&& eq_expr_value(cx, rhs0, lhs1)
308-
&& eq_expr_value(cx, lhs1, rhs2);
222+
if eq_expr_value(cx, lhs0, rhs1);
223+
if eq_expr_value(cx, lhs2, rhs1);
224+
if eq_expr_value(cx, lhs1, rhs0);
225+
if eq_expr_value(cx, lhs1, rhs2);
309226
then {
310227
let span = window[0].span.to(window[2].span);
311-
let mut applicability = Applicability::MachineApplicable;
312-
match check_for_slice(cx, lhs0, rhs0) {
313-
Slice::Swappable(slice, idx0, idx1) => {
314-
if let Some(slice) = Sugg::hir_opt(cx, slice) {
315-
span_lint_and_sugg(
316-
cx,
317-
XOR_SWAP,
318-
span,
319-
&format!(
320-
"this xor-based swap of the elements of `{}` can be \
321-
more clearly expressed using `.swap`",
322-
slice
323-
),
324-
"try",
325-
format!(
326-
"{}.swap({}, {})",
327-
slice.maybe_par(),
328-
snippet_with_applicability(cx, idx0.span, "..", &mut applicability),
329-
snippet_with_applicability(cx, idx1.span, "..", &mut applicability)
330-
),
331-
applicability
332-
)
333-
}
334-
}
335-
Slice::None => {
336-
if let (Some(first), Some(second)) = (Sugg::hir_opt(cx, lhs0), Sugg::hir_opt(cx, rhs0)) {
337-
span_lint_and_sugg(
338-
cx,
339-
XOR_SWAP,
340-
span,
341-
&format!(
342-
"this xor-based swap of `{}` and `{}` can be \
343-
more clearly expressed using `std::mem::swap`",
344-
first, second
345-
),
346-
"try",
347-
format!("std::mem::swap({}, {})", first.mut_addr(), second.mut_addr()),
348-
applicability,
349-
);
350-
}
351-
}
352-
Slice::NotSwappable => {}
353-
}
228+
generate_swap_warning(cx, lhs0, rhs0, span, true);
354229
}
355230
};
356231
}

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