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Add lint transmute_num_to_bytes

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Closes #7803

changelog: [`transmute_num_to_bytes`] new lint
This commit is contained in:
Nixon Enraght-Moony 2021-10-11 23:46:49 +01:00
parent 72723663a3
commit 58969807ab
8 changed files with 194 additions and 3 deletions
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1
CHANGELOG.md
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@ -3024,6 +3024,7 @@ Released 2018-09-13
[`transmute_int_to_bool`]: https://rust-lang.github.io/rust-clippy/master/index.html#transmute_int_to_bool
[`transmute_int_to_char`]: https://rust-lang.github.io/rust-clippy/master/index.html#transmute_int_to_char
[`transmute_int_to_float`]: https://rust-lang.github.io/rust-clippy/master/index.html#transmute_int_to_float
[`transmute_num_to_bytes`]: https://rust-lang.github.io/rust-clippy/master/index.html#transmute_num_to_bytes
[`transmute_ptr_to_ptr`]: https://rust-lang.github.io/rust-clippy/master/index.html#transmute_ptr_to_ptr
[`transmute_ptr_to_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#transmute_ptr_to_ref
[`transmutes_expressible_as_ptr_casts`]: https://rust-lang.github.io/rust-clippy/master/index.html#transmutes_expressible_as_ptr_casts

1
clippy_lints/src/lib.register_all.rs
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@ -266,6 +266,7 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![
LintId::of(transmute::TRANSMUTE_INT_TO_BOOL),
LintId::of(transmute::TRANSMUTE_INT_TO_CHAR),
LintId::of(transmute::TRANSMUTE_INT_TO_FLOAT),
LintId::of(transmute::TRANSMUTE_NUM_TO_BYTES),
LintId::of(transmute::TRANSMUTE_PTR_TO_REF),
LintId::of(transmute::UNSOUND_COLLECTION_TRANSMUTE),
LintId::of(transmute::WRONG_TRANSMUTE),

1
clippy_lints/src/lib.register_complexity.rs
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@ -82,6 +82,7 @@ store.register_group(true, "clippy::complexity", Some("clippy_complexity"), vec!
LintId::of(transmute::TRANSMUTE_INT_TO_BOOL),
LintId::of(transmute::TRANSMUTE_INT_TO_CHAR),
LintId::of(transmute::TRANSMUTE_INT_TO_FLOAT),
LintId::of(transmute::TRANSMUTE_NUM_TO_BYTES),
LintId::of(transmute::TRANSMUTE_PTR_TO_REF),
LintId::of(types::BORROWED_BOX),
LintId::of(types::TYPE_COMPLEXITY),

1
clippy_lints/src/lib.register_lints.rs
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@ -449,6 +449,7 @@ store.register_lints(&[
transmute::TRANSMUTE_INT_TO_BOOL,
transmute::TRANSMUTE_INT_TO_CHAR,
transmute::TRANSMUTE_INT_TO_FLOAT,
transmute::TRANSMUTE_NUM_TO_BYTES,
transmute::TRANSMUTE_PTR_TO_PTR,
transmute::TRANSMUTE_PTR_TO_REF,
transmute::UNSOUND_COLLECTION_TRANSMUTE,

25
clippy_lints/src/transmute/mod.rs
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@ -3,6 +3,7 @@ mod transmute_float_to_int;
mod transmute_int_to_bool;
mod transmute_int_to_char;
mod transmute_int_to_float;
mod transmute_num_to_bytes;
mod transmute_ptr_to_ptr;
mod transmute_ptr_to_ref;
mod transmute_ref_to_ref;
@ -261,6 +262,28 @@ declare_clippy_lint! {
"transmutes from a float to an integer"
}
declare_clippy_lint! {
/// # What it does
/// Checks for transmutes from a number to an array of `u8`
///
/// ### Why this is bad?
/// Transmutes are dangerous and error-prone, whereas `to_ne_bytes`
/// is intuitive and safe.
///
/// ### Example
/// ```rust
/// unsafe {
/// let x: [u8; 8] = std::mem::transmute(1i64);
/// }
///
/// // should be
/// let x: [u8; 8] = 0i64.to_ne_bytes();
/// ```
pub TRANSMUTE_NUM_TO_BYTES,
complexity,
"transmutes from a number to an array of `u8`"
}
declare_clippy_lint! {
/// ### What it does
/// Checks for transmutes from a pointer to a pointer, or
@ -330,6 +353,7 @@ declare_lint_pass!(Transmute => [
TRANSMUTE_INT_TO_BOOL,
TRANSMUTE_INT_TO_FLOAT,
TRANSMUTE_FLOAT_TO_INT,
TRANSMUTE_NUM_TO_BYTES,
UNSOUND_COLLECTION_TRANSMUTE,
TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS,
]);
@ -365,6 +389,7 @@ impl<'tcx> LateLintPass<'tcx> for Transmute {
linted |= transmute_int_to_bool::check(cx, e, from_ty, to_ty, args);
linted |= transmute_int_to_float::check(cx, e, from_ty, to_ty, args, const_context);
linted |= transmute_float_to_int::check(cx, e, from_ty, to_ty, args, const_context);
linted |= transmute_num_to_bytes::check(cx, e, from_ty, to_ty, args, const_context);
linted |= unsound_collection_transmute::check(cx, e, from_ty, to_ty);
if !linted {

49
clippy_lints/src/transmute/transmute_num_to_bytes.rs Normal file
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@ -0,0 +1,49 @@
use super::TRANSMUTE_NUM_TO_BYTES;
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::sugg;
use rustc_errors::Applicability;
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty, UintTy};
/// Checks for `transmute_int_to_float` lint.
/// Returns `true` if it's triggered, otherwise returns `false`.
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
const_context: bool,
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
(ty::Int(_) | ty::Uint(_) | ty::Float(_), ty::Array(arr_ty, _)) => {
if !matches!(arr_ty.kind(), ty::Uint(UintTy::U8)) {
return false;
}
if matches!(from_ty.kind(), ty::Float(_)) && const_context {
// TODO: Remove when const_float_bits_conv is stabilized
// rust#72447
return false;
}
span_lint_and_then(
cx,
TRANSMUTE_NUM_TO_BYTES,
e.span,
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
|diag| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
diag.span_suggestion(
e.span,
"consider using `to_ne_bytes()`",
format!("{}.to_ne_bytes()", arg.to_string()),
Applicability::Unspecified,
);
},
);
true
},
_ => false,
}
}

27
tests/ui/transmute.rs
View File

@ -103,6 +103,33 @@ mod int_to_float {
}
}
mod num_to_bytes {
fn test() {
unsafe {
let _: [u8; 1] = std::mem::transmute(0u8);
let _: [u8; 4] = std::mem::transmute(0u32);
let _: [u8; 16] = std::mem::transmute(0u128);
let _: [u8; 1] = std::mem::transmute(0i8);
let _: [u8; 4] = std::mem::transmute(0i32);
let _: [u8; 16] = std::mem::transmute(0i128);
let _: [u8; 4] = std::mem::transmute(0.0f32);
let _: [u8; 8] = std::mem::transmute(0.0f64);
}
}
const fn test_const() {
unsafe {
let _: [u8; 1] = std::mem::transmute(0u8);
let _: [u8; 4] = std::mem::transmute(0u32);
let _: [u8; 16] = std::mem::transmute(0u128);
let _: [u8; 1] = std::mem::transmute(0i8);
let _: [u8; 4] = std::mem::transmute(0i32);
let _: [u8; 16] = std::mem::transmute(0i128);
let _: [u8; 4] = std::mem::transmute(0.0f32);
let _: [u8; 8] = std::mem::transmute(0.0f64);
}
}
}
fn bytes_to_str(b: &[u8], mb: &mut [u8]) {
let _: &str = unsafe { std::mem::transmute(b) };
let _: &mut str = unsafe { std::mem::transmute(mb) };

92
tests/ui/transmute.stderr
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@ -140,8 +140,94 @@ error: transmute from a `i64` to a `f64`
LL | let _: f64 = unsafe { std::mem::transmute(0_i64) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `f64::from_bits(0_i64 as u64)`
error: transmute from a `u8` to a `[u8; 1]`
--> $DIR/transmute.rs:109:30
|
LL | let _: [u8; 1] = std::mem::transmute(0u8);
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0u8.to_ne_bytes()`
|
= note: `-D clippy::transmute-num-to-bytes` implied by `-D warnings`
error: transmute from a `u32` to a `[u8; 4]`
--> $DIR/transmute.rs:110:30
|
LL | let _: [u8; 4] = std::mem::transmute(0u32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0u32.to_ne_bytes()`
error: transmute from a `u128` to a `[u8; 16]`
--> $DIR/transmute.rs:111:31
|
LL | let _: [u8; 16] = std::mem::transmute(0u128);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0u128.to_ne_bytes()`
error: transmute from a `i8` to a `[u8; 1]`
--> $DIR/transmute.rs:112:30
|
LL | let _: [u8; 1] = std::mem::transmute(0i8);
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0i8.to_ne_bytes()`
error: transmute from a `i32` to a `[u8; 4]`
--> $DIR/transmute.rs:113:30
|
LL | let _: [u8; 4] = std::mem::transmute(0i32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0i32.to_ne_bytes()`
error: transmute from a `i128` to a `[u8; 16]`
--> $DIR/transmute.rs:114:31
|
LL | let _: [u8; 16] = std::mem::transmute(0i128);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0i128.to_ne_bytes()`
error: transmute from a `f32` to a `[u8; 4]`
--> $DIR/transmute.rs:115:30
|
LL | let _: [u8; 4] = std::mem::transmute(0.0f32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0.0f32.to_ne_bytes()`
error: transmute from a `f64` to a `[u8; 8]`
--> $DIR/transmute.rs:116:30
|
LL | let _: [u8; 8] = std::mem::transmute(0.0f64);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0.0f64.to_ne_bytes()`
error: transmute from a `u8` to a `[u8; 1]`
--> $DIR/transmute.rs:121:30
|
LL | let _: [u8; 1] = std::mem::transmute(0u8);
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0u8.to_ne_bytes()`
error: transmute from a `u32` to a `[u8; 4]`
--> $DIR/transmute.rs:122:30
|
LL | let _: [u8; 4] = std::mem::transmute(0u32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0u32.to_ne_bytes()`
error: transmute from a `u128` to a `[u8; 16]`
--> $DIR/transmute.rs:123:31
|
LL | let _: [u8; 16] = std::mem::transmute(0u128);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0u128.to_ne_bytes()`
error: transmute from a `i8` to a `[u8; 1]`
--> $DIR/transmute.rs:124:30
|
LL | let _: [u8; 1] = std::mem::transmute(0i8);
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0i8.to_ne_bytes()`
error: transmute from a `i32` to a `[u8; 4]`
--> $DIR/transmute.rs:125:30
|
LL | let _: [u8; 4] = std::mem::transmute(0i32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0i32.to_ne_bytes()`
error: transmute from a `i128` to a `[u8; 16]`
--> $DIR/transmute.rs:126:31
|
LL | let _: [u8; 16] = std::mem::transmute(0i128);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `to_ne_bytes()`: `0i128.to_ne_bytes()`
error: transmute from a `&[u8]` to a `&str`
--> $DIR/transmute.rs:107:28
--> $DIR/transmute.rs:134:28
|
LL | let _: &str = unsafe { std::mem::transmute(b) };
| ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8(b).unwrap()`
@ -149,10 +235,10 @@ LL | let _: &str = unsafe { std::mem::transmute(b) };
= note: `-D clippy::transmute-bytes-to-str` implied by `-D warnings`
error: transmute from a `&mut [u8]` to a `&mut str`
--> $DIR/transmute.rs:108:32
--> $DIR/transmute.rs:135:32
|
LL | let _: &mut str = unsafe { std::mem::transmute(mb) };
| ^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8_mut(mb).unwrap()`
error: aborting due to 24 previous errors
error: aborting due to 38 previous errors