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Centri3Centri3
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emit unnecessary_cast on raw pointers as well
1 parent b6284f0 commit 7f7979f

12 files changed

+138
-52
lines changed

‎clippy_lints/src/casts/mod.rs

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -175,8 +175,8 @@ declare_clippy_lint! {
175175

176176
declare_clippy_lint! {
177177
/// ### What it does
178-
/// Checks for casts to the same type, casts of int literals to integer types
179-
/// and casts of float literals to float types.
178+
/// Checks for casts to the same type, casts of int literals to integer types, casts of float
179+
/// literals to float types and casts between raw pointers without changing type or constness.
180180
///
181181
/// ### Why is this bad?
182182
/// It's just unnecessary.

‎clippy_lints/src/casts/unnecessary_cast.rs

Lines changed: 34 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,7 @@
11
use clippy_utils::diagnostics::span_lint_and_sugg;
22
use clippy_utils::numeric_literal::NumericLiteral;
33
use clippy_utils::source::snippet_opt;
4-
use clippy_utils::{get_parent_expr, path_to_local};
4+
use clippy_utils::{get_parent_expr, is_ty_alias, path_to_local};
55
use if_chain::if_chain;
66
use rustc_ast::{LitFloatType, LitIntType, LitKind};
77
use rustc_errors::Applicability;
@@ -20,19 +20,49 @@ pub(super) fn check<'tcx>(
2020
cast_from: Ty<'tcx>,
2121
cast_to: Ty<'tcx>,
2222
) -> bool {
23+
let cast_str = snippet_opt(cx, cast_expr.span).unwrap_or_default();
24+
25+
if_chain! {
26+
if let ty::RawPtr(..) = cast_from.kind();
27+
// check both mutability and type are the same
28+
if cast_from.kind() == cast_to.kind();
29+
if let ExprKind::Cast(_, cast_to_hir) = expr.kind;
30+
then {
31+
if_chain! {
32+
if let TyKind::Path(qpath) = cast_to_hir.kind;
33+
if is_ty_alias(&qpath);
34+
then {
35+
return false;
36+
}
37+
}
38+
39+
if let TyKind::Infer = cast_to_hir.kind {
40+
return false;
41+
}
42+
43+
span_lint_and_sugg(
44+
cx,
45+
UNNECESSARY_CAST,
46+
expr.span,
47+
&format!("casting raw pointers to the same type and constness is unnecessary (`{cast_from}` -> `{cast_to}`)"),
48+
"try",
49+
cast_str.clone(),
50+
Applicability::MachineApplicable,
51+
);
52+
}
53+
}
54+
2355
// skip non-primitive type cast
2456
if_chain! {
2557
if let ExprKind::Cast(_, cast_to) = expr.kind;
2658
if let TyKind::Path(QPath::Resolved(_, path)) = &cast_to.kind;
2759
if let Res::PrimTy(_) = path.res;
2860
then {}
2961
else {
30-
return false
62+
return false;
3163
}
3264
}
3365

34-
let cast_str = snippet_opt(cx, cast_expr.span).unwrap_or_default();
35-
3666
if let Some(lit) = get_numeric_literal(cast_expr) {
3767
let literal_str = &cast_str;
3868

‎tests/ui/as_ptr_cast_mut.stderr

Lines changed: 15 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -12,5 +12,19 @@ error: casting the result of `as_ptr` to *mut i8
1212
LL | let _: *mut i8 = string.as_ptr() as *mut _;
1313
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `string.as_mut_ptr()`
1414

15-
error: aborting due to 2 previous errors
15+
error: casting raw pointers to the same type and constness is unnecessary (`*mut u8` -> `*mut u8`)
16+
--> $DIR/as_ptr_cast_mut.rs:25:13
17+
|
18+
LL | let _ = string.as_mut_ptr() as *mut u8;
19+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `string.as_mut_ptr()`
20+
|
21+
= note: `-D clippy::unnecessary-cast` implied by `-D warnings`
22+
23+
error: casting raw pointers to the same type and constness is unnecessary (`*mut u8` -> `*mut u8`)
24+
--> $DIR/as_ptr_cast_mut.rs:29:13
25+
|
26+
LL | let _ = nn.as_ptr() as *mut u8;
27+
| ^^^^^^^^^^^^^^^^^^^^^^ help: try: `nn.as_ptr()`
28+
29+
error: aborting due to 4 previous errors
1630

‎tests/ui/cast_slice_different_sizes.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
#![allow(clippy::let_unit_value)]
1+
#![allow(clippy::let_unit_value, clippy::unnecessary_cast)]
22

33
fn main() {
44
let x: [i32; 3] = [1_i32, 2, 3];

‎tests/ui/crashes/ice-1782.rs

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,5 @@
11
#![allow(dead_code, unused_variables)]
2+
#![allow(clippy::unnecessary_cast)]
23

34
/// Should not trigger an ICE in `SpanlessEq` / `consts::constant`
45
///

‎tests/ui/from_raw_with_void_ptr.rs

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,5 @@
11
#![warn(clippy::from_raw_with_void_ptr)]
2+
#![allow(clippy::unnecessary_cast)]
23

34
use std::ffi::c_void;
45
use std::rc::Rc;

‎tests/ui/from_raw_with_void_ptr.stderr

Lines changed: 10 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -1,60 +1,60 @@
11
error: creating a `Box` from a void raw pointer
2-
--> $DIR/from_raw_with_void_ptr.rs:10:22
2+
--> $DIR/from_raw_with_void_ptr.rs:11:22
33
|
44
LL | let _ = unsafe { Box::from_raw(ptr) };
55
| ^^^^^^^^^^^^^^^^^^
66
|
77
help: cast this to a pointer of the appropriate type
8-
--> $DIR/from_raw_with_void_ptr.rs:10:36
8+
--> $DIR/from_raw_with_void_ptr.rs:11:36
99
|
1010
LL | let _ = unsafe { Box::from_raw(ptr) };
1111
| ^^^
1212
= note: `-D clippy::from-raw-with-void-ptr` implied by `-D warnings`
1313

1414
error: creating a `Rc` from a void raw pointer
15-
--> $DIR/from_raw_with_void_ptr.rs:21:22
15+
--> $DIR/from_raw_with_void_ptr.rs:22:22
1616
|
1717
LL | let _ = unsafe { Rc::from_raw(ptr) };
1818
| ^^^^^^^^^^^^^^^^^
1919
|
2020
help: cast this to a pointer of the appropriate type
21-
--> $DIR/from_raw_with_void_ptr.rs:21:35
21+
--> $DIR/from_raw_with_void_ptr.rs:22:35
2222
|
2323
LL | let _ = unsafe { Rc::from_raw(ptr) };
2424
| ^^^
2525

2626
error: creating a `Arc` from a void raw pointer
27-
--> $DIR/from_raw_with_void_ptr.rs:25:22
27+
--> $DIR/from_raw_with_void_ptr.rs:26:22
2828
|
2929
LL | let _ = unsafe { Arc::from_raw(ptr) };
3030
| ^^^^^^^^^^^^^^^^^^
3131
|
3232
help: cast this to a pointer of the appropriate type
33-
--> $DIR/from_raw_with_void_ptr.rs:25:36
33+
--> $DIR/from_raw_with_void_ptr.rs:26:36
3434
|
3535
LL | let _ = unsafe { Arc::from_raw(ptr) };
3636
| ^^^
3737

3838
error: creating a `Weak` from a void raw pointer
39-
--> $DIR/from_raw_with_void_ptr.rs:29:22
39+
--> $DIR/from_raw_with_void_ptr.rs:30:22
4040
|
4141
LL | let _ = unsafe { std::rc::Weak::from_raw(ptr) };
4242
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
4343
|
4444
help: cast this to a pointer of the appropriate type
45-
--> $DIR/from_raw_with_void_ptr.rs:29:46
45+
--> $DIR/from_raw_with_void_ptr.rs:30:46
4646
|
4747
LL | let _ = unsafe { std::rc::Weak::from_raw(ptr) };
4848
| ^^^
4949

5050
error: creating a `Weak` from a void raw pointer
51-
--> $DIR/from_raw_with_void_ptr.rs:33:22
51+
--> $DIR/from_raw_with_void_ptr.rs:34:22
5252
|
5353
LL | let _ = unsafe { std::sync::Weak::from_raw(ptr) };
5454
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
5555
|
5656
help: cast this to a pointer of the appropriate type
57-
--> $DIR/from_raw_with_void_ptr.rs:33:48
57+
--> $DIR/from_raw_with_void_ptr.rs:34:48
5858
|
5959
LL | let _ = unsafe { std::sync::Weak::from_raw(ptr) };
6060
| ^^^

‎tests/ui/transmute_ptr_to_ref.fixed

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,7 @@
11
//@run-rustfix
22

33
#![warn(clippy::transmute_ptr_to_ref)]
4-
#![allow(clippy::match_single_binding)]
4+
#![allow(clippy::match_single_binding, clippy::unnecessary_cast)]
55

66
unsafe fn _ptr_to_ref<T, U>(p: *const T, m: *mut T, o: *const U, om: *mut U) {
77
let _: &T = &*p;

‎tests/ui/transmute_ptr_to_ref.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,7 @@
11
//@run-rustfix
22

33
#![warn(clippy::transmute_ptr_to_ref)]
4-
#![allow(clippy::match_single_binding)]
4+
#![allow(clippy::match_single_binding, clippy::unnecessary_cast)]
55

66
unsafe fn _ptr_to_ref<T, U>(p: *const T, m: *mut T, o: *const U, om: *mut U) {
77
let _: &T = std::mem::transmute(p);

‎tests/ui/unnecessary_cast.fixed

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -8,6 +8,9 @@
88
clippy::unnecessary_operation
99
)]
1010

11+
type PtrConstU8 = *const u8;
12+
type PtrMutU8 = *mut u8;
13+
1114
#[rustfmt::skip]
1215
fn main() {
1316
// Test cast_unnecessary
@@ -22,6 +25,17 @@ fn main() {
2225
1_i32;
2326
1_f32;
2427

28+
[1u8, 2].as_ptr();
29+
[1u8, 2].as_ptr() as *mut u8;
30+
[1u8, 2].as_mut_ptr();
31+
[1u8, 2].as_mut_ptr() as *const u8;
32+
[1u8, 2].as_ptr() as PtrConstU8;
33+
[1u8, 2].as_ptr() as PtrMutU8;
34+
[1u8, 2].as_mut_ptr() as PtrMutU8;
35+
[1u8, 2].as_mut_ptr() as PtrConstU8;
36+
let _: *const u8 = [1u8, 2].as_ptr() as _;
37+
let _: *mut u8 = [1u8, 2].as_mut_ptr() as _;
38+
2539
// macro version
2640
macro_rules! foo {
2741
($a:ident, $b:ident) => {

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