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Auto merge of rust-lang#10910 - Alexendoo:unnecessary-pointer-casts, …
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…r=llogiq

Ignore more pointer types in `unnecessary_cast`

Spotted this because

https://github.com/rust-lang/rust-clippy/blob/e2c655b4c07c912ef749be316aeea8453cb9d840/tests/ui/suspicious_to_owned.rs#L9-L10

currently fails on `aarch64-unknown-linux-gnu` as `c_char` is `u8` there

The current implementation checks for `as alias`, `as _`. This adds things like
- `as *const alias`
- `as *const cfg_dependant`
- `as *const _`

changelog: none
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@bors
bors committed Jun 8, 2023
2 parents e2c655b + 4346c99 commit 384cf37
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Showing 4 changed files with 69 additions and 37 deletions.
28 changes: 17 additions & 11 deletions clippy_lints/src/casts/unnecessary_cast.rs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::numeric_literal::NumericLiteral;
use clippy_utils::source::snippet_opt;
use clippy_utils::{get_parent_expr, is_ty_alias, path_to_local};
use clippy_utils::{get_parent_expr, is_hir_ty_cfg_dependant, is_ty_alias, path_to_local};
use if_chain::if_chain;
use rustc_ast::{LitFloatType, LitIntType, LitKind};
use rustc_errors::Applicability;
Expand All @@ -27,17 +27,23 @@ pub(super) fn check<'tcx>(
// check both mutability and type are the same
if cast_from.kind() == cast_to.kind();
if let ExprKind::Cast(_, cast_to_hir) = expr.kind;
// Ignore casts to e.g. type aliases and infer types
// - p as pointer_alias
// - p as _
if let TyKind::Ptr(to_pointee) = cast_to_hir.kind;
then {
if_chain! {
if let TyKind::Path(qpath) = cast_to_hir.kind;
if is_ty_alias(&qpath);
then {
return false;
}
}

if let TyKind::Infer = cast_to_hir.kind {
return false;
match to_pointee.ty.kind {
// Ignore casts to pointers that are aliases or cfg dependant, e.g.
// - p as *const std::ffi::c_char (alias)
// - p as *const std::os::raw::c_char (cfg dependant)
TyKind::Path(qpath) => {
if is_ty_alias(&qpath) || is_hir_ty_cfg_dependant(cx, to_pointee.ty) {
return false;
}
},
// Ignore `p as *const _`
TyKind::Infer => return false,
_ => {},
}

span_lint_and_sugg(
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13 changes: 13 additions & 0 deletions tests/ui/unnecessary_cast.fixed
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,8 @@ fn main() {
[1u8, 2].as_mut_ptr() as PtrConstU8;
let _: *const u8 = [1u8, 2].as_ptr() as _;
let _: *mut u8 = [1u8, 2].as_mut_ptr() as _;
let _: *const u8 = [1u8, 2].as_ptr() as *const _;
let _: *mut u8 = [1u8, 2].as_mut_ptr() as *mut _;

owo::<u32>([1u32].as_ptr());
uwu::<u32, u8>([1u32].as_ptr());
Expand All @@ -71,6 +73,17 @@ fn main() {
1 as I32Alias;
&1 as &I32Alias;

let i8_ptr: *const i8 = &1;
let u8_ptr: *const u8 = &1;

// cfg dependant pointees
i8_ptr as *const std::os::raw::c_char;
u8_ptr as *const std::os::raw::c_char;

// type aliased pointees
i8_ptr as *const std::ffi::c_char;
u8_ptr as *const std::ffi::c_char;

// issue #9960
macro_rules! bind_var {
($id:ident, $e:expr) => {{
Expand Down
13 changes: 13 additions & 0 deletions tests/ui/unnecessary_cast.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,8 @@ fn main() {
[1u8, 2].as_mut_ptr() as PtrConstU8;
let _: *const u8 = [1u8, 2].as_ptr() as _;
let _: *mut u8 = [1u8, 2].as_mut_ptr() as _;
let _: *const u8 = [1u8, 2].as_ptr() as *const _;
let _: *mut u8 = [1u8, 2].as_mut_ptr() as *mut _;

owo::<u32>([1u32].as_ptr()) as *const u32;
uwu::<u32, u8>([1u32].as_ptr()) as *const u8;
Expand All @@ -71,6 +73,17 @@ fn main() {
1 as I32Alias;
&1 as &I32Alias;

let i8_ptr: *const i8 = &1;
let u8_ptr: *const u8 = &1;

// cfg dependant pointees
i8_ptr as *const std::os::raw::c_char;
u8_ptr as *const std::os::raw::c_char;

// type aliased pointees
i8_ptr as *const std::ffi::c_char;
u8_ptr as *const std::ffi::c_char;

// issue #9960
macro_rules! bind_var {
($id:ident, $e:expr) => {{
Expand Down
52 changes: 26 additions & 26 deletions tests/ui/unnecessary_cast.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -73,157 +73,157 @@ LL | [1u8, 2].as_mut_ptr() as *mut u8;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `[1u8, 2].as_mut_ptr()`

error: casting raw pointers to the same type and constness is unnecessary (`*const u32` -> `*const u32`)
--> $DIR/unnecessary_cast.rs:49:5
--> $DIR/unnecessary_cast.rs:51:5
|
LL | owo::<u32>([1u32].as_ptr()) as *const u32;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `owo::<u32>([1u32].as_ptr())`

error: casting raw pointers to the same type and constness is unnecessary (`*const u8` -> `*const u8`)
--> $DIR/unnecessary_cast.rs:50:5
--> $DIR/unnecessary_cast.rs:52:5
|
LL | uwu::<u32, u8>([1u32].as_ptr()) as *const u8;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `uwu::<u32, u8>([1u32].as_ptr())`

error: casting raw pointers to the same type and constness is unnecessary (`*const u32` -> `*const u32`)
--> $DIR/unnecessary_cast.rs:52:5
--> $DIR/unnecessary_cast.rs:54:5
|
LL | uwu::<u32, u32>([1u32].as_ptr()) as *const u32;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `uwu::<u32, u32>([1u32].as_ptr())`

error: casting integer literal to `f32` is unnecessary
--> $DIR/unnecessary_cast.rs:93:9
--> $DIR/unnecessary_cast.rs:106:9
|
LL | 100 as f32;
| ^^^^^^^^^^ help: try: `100_f32`

error: casting integer literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:94:9
--> $DIR/unnecessary_cast.rs:107:9
|
LL | 100 as f64;
| ^^^^^^^^^^ help: try: `100_f64`

error: casting integer literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:95:9
--> $DIR/unnecessary_cast.rs:108:9
|
LL | 100_i32 as f64;
| ^^^^^^^^^^^^^^ help: try: `100_f64`

error: casting integer literal to `f32` is unnecessary
--> $DIR/unnecessary_cast.rs:96:17
--> $DIR/unnecessary_cast.rs:109:17
|
LL | let _ = -100 as f32;
| ^^^^^^^^^^^ help: try: `-100_f32`

error: casting integer literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:97:17
--> $DIR/unnecessary_cast.rs:110:17
|
LL | let _ = -100 as f64;
| ^^^^^^^^^^^ help: try: `-100_f64`

error: casting integer literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:98:17
--> $DIR/unnecessary_cast.rs:111:17
|
LL | let _ = -100_i32 as f64;
| ^^^^^^^^^^^^^^^ help: try: `-100_f64`

error: casting float literal to `f32` is unnecessary
--> $DIR/unnecessary_cast.rs:99:9
--> $DIR/unnecessary_cast.rs:112:9
|
LL | 100. as f32;
| ^^^^^^^^^^^ help: try: `100_f32`

error: casting float literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:100:9
--> $DIR/unnecessary_cast.rs:113:9
|
LL | 100. as f64;
| ^^^^^^^^^^^ help: try: `100_f64`

error: casting integer literal to `u32` is unnecessary
--> $DIR/unnecessary_cast.rs:112:9
--> $DIR/unnecessary_cast.rs:125:9
|
LL | 1 as u32;
| ^^^^^^^^ help: try: `1_u32`

error: casting integer literal to `i32` is unnecessary
--> $DIR/unnecessary_cast.rs:113:9
--> $DIR/unnecessary_cast.rs:126:9
|
LL | 0x10 as i32;
| ^^^^^^^^^^^ help: try: `0x10_i32`

error: casting integer literal to `usize` is unnecessary
--> $DIR/unnecessary_cast.rs:114:9
--> $DIR/unnecessary_cast.rs:127:9
|
LL | 0b10 as usize;
| ^^^^^^^^^^^^^ help: try: `0b10_usize`

error: casting integer literal to `u16` is unnecessary
--> $DIR/unnecessary_cast.rs:115:9
--> $DIR/unnecessary_cast.rs:128:9
|
LL | 0o73 as u16;
| ^^^^^^^^^^^ help: try: `0o73_u16`

error: casting integer literal to `u32` is unnecessary
--> $DIR/unnecessary_cast.rs:116:9
--> $DIR/unnecessary_cast.rs:129:9
|
LL | 1_000_000_000 as u32;
| ^^^^^^^^^^^^^^^^^^^^ help: try: `1_000_000_000_u32`

error: casting float literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:118:9
--> $DIR/unnecessary_cast.rs:131:9
|
LL | 1.0 as f64;
| ^^^^^^^^^^ help: try: `1.0_f64`

error: casting float literal to `f32` is unnecessary
--> $DIR/unnecessary_cast.rs:119:9
--> $DIR/unnecessary_cast.rs:132:9
|
LL | 0.5 as f32;
| ^^^^^^^^^^ help: try: `0.5_f32`

error: casting integer literal to `i32` is unnecessary
--> $DIR/unnecessary_cast.rs:123:17
--> $DIR/unnecessary_cast.rs:136:17
|
LL | let _ = -1 as i32;
| ^^^^^^^^^ help: try: `-1_i32`

error: casting float literal to `f32` is unnecessary
--> $DIR/unnecessary_cast.rs:124:17
--> $DIR/unnecessary_cast.rs:137:17
|
LL | let _ = -1.0 as f32;
| ^^^^^^^^^^^ help: try: `-1.0_f32`

error: casting to the same type is unnecessary (`i32` -> `i32`)
--> $DIR/unnecessary_cast.rs:130:18
--> $DIR/unnecessary_cast.rs:143:18
|
LL | let _ = &(x as i32);
| ^^^^^^^^^^ help: try: `{ x }`

error: casting integer literal to `i32` is unnecessary
--> $DIR/unnecessary_cast.rs:136:22
--> $DIR/unnecessary_cast.rs:149:22
|
LL | let _: i32 = -(1) as i32;
| ^^^^^^^^^^^ help: try: `-1_i32`

error: casting integer literal to `i64` is unnecessary
--> $DIR/unnecessary_cast.rs:138:22
--> $DIR/unnecessary_cast.rs:151:22
|
LL | let _: i64 = -(1) as i64;
| ^^^^^^^^^^^ help: try: `-1_i64`

error: casting float literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:145:22
--> $DIR/unnecessary_cast.rs:158:22
|
LL | let _: f64 = (-8.0 as f64).exp();
| ^^^^^^^^^^^^^ help: try: `(-8.0_f64)`

error: casting float literal to `f64` is unnecessary
--> $DIR/unnecessary_cast.rs:147:23
--> $DIR/unnecessary_cast.rs:160:23
|
LL | let _: f64 = -(8.0 as f64).exp(); // should suggest `-8.0_f64.exp()` here not to change code behavior
| ^^^^^^^^^^^^ help: try: `8.0_f64`

error: casting to the same type is unnecessary (`f32` -> `f32`)
--> $DIR/unnecessary_cast.rs:155:20
--> $DIR/unnecessary_cast.rs:168:20
|
LL | let _num = foo() as f32;
| ^^^^^^^^^^^^ help: try: `foo()`
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