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Deprecate misaligned_transmute

This commit is contained in:
Devon Hollowood 2018-04-11 02:50:04 -07:00
parent c6bc682325
commit b77d74030b
7 changed files with 33 additions and 58 deletions
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11
clippy_lints/src/deprecated_lints.rs
View File

@ -71,3 +71,14 @@ declare_deprecated_lint! {
pub STRING_TO_STRING,
"using `string::to_string` is common even today and specialization will likely happen soon"
}
/// **What it does:** Nothing. This lint has been deprecated.
///
/// **Deprecation reason:** This lint should never have applied to non-pointer types, as transmuting
/// between non-pointer types of differing alignment is well-defined behavior (it's semantically
/// equivalent to a memcpy). This lint has thus been refactored into two separate lints:
/// cast_ptr_alignment and transmute_ptr_to_ptr.
declare_deprecated_lint! {
pub MISALIGNED_TRANSMUTE,
"this lint has been split into cast_ptr_alignment and transmute_ptr_to_ptr"
}

6
clippy_lints/src/lib.rs
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@ -277,6 +277,10 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
"string_to_string",
"using `string::to_string` is common even today and specialization will likely happen soon",
);
store.register_removed(
"misaligned_transmute",
"this lint has been split into cast_ptr_alignment and transmute_ptr_to_ptr",
);
// end deprecated lints, do not remove this comment, it’s used in `update_lints`
reg.register_late_lint_pass(box serde_api::Serde);
@ -635,7 +639,6 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
swap::MANUAL_SWAP,
temporary_assignment::TEMPORARY_ASSIGNMENT,
transmute::CROSSPOINTER_TRANSMUTE,
transmute::MISALIGNED_TRANSMUTE,
transmute::TRANSMUTE_BYTES_TO_STR,
transmute::TRANSMUTE_INT_TO_BOOL,
transmute::TRANSMUTE_INT_TO_CHAR,
@ -787,7 +790,6 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
swap::MANUAL_SWAP,
temporary_assignment::TEMPORARY_ASSIGNMENT,
transmute::CROSSPOINTER_TRANSMUTE,
transmute::MISALIGNED_TRANSMUTE,
transmute::TRANSMUTE_BYTES_TO_STR,
transmute::TRANSMUTE_INT_TO_BOOL,
transmute::TRANSMUTE_INT_TO_CHAR,

31
clippy_lints/src/transmute.rs
View File

@ -1,7 +1,6 @@
use rustc::lint::*;
use rustc::ty::{self, Ty};
use rustc::hir::*;
use rustc::ty::layout::LayoutOf;
use std::borrow::Cow;
use syntax::ast;
use utils::{last_path_segment, match_def_path, paths, snippet, span_lint, span_lint_and_then};
@ -169,23 +168,6 @@ declare_clippy_lint! {
"transmutes from an integer to a float"
}
/// **What it does:** Checks for transmutes to a potentially less-aligned type.
///
/// **Why is this bad?** This might result in undefined behavior.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// // u32 is 32-bit aligned; u8 is 8-bit aligned
/// let _: u32 = unsafe { std::mem::transmute([0u8; 4]) };
/// ```
declare_clippy_lint! {
pub MISALIGNED_TRANSMUTE,
complexity,
"transmutes to a potentially less-aligned type"
}
/// **What it does:** Checks for transmutes from a pointer to a pointer, or
/// from a reference to a reference.
///
@ -227,7 +209,6 @@ impl LintPass for Transmute {
TRANSMUTE_BYTES_TO_STR,
TRANSMUTE_INT_TO_BOOL,
TRANSMUTE_INT_TO_FLOAT,
MISALIGNED_TRANSMUTE
)
}
}
@ -248,18 +229,6 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Transmute {
e.span,
&format!("transmute from a type (`{}`) to itself", from_ty),
),
_ if cx.layout_of(from_ty).ok().map(|a| a.align.abi())
< cx.layout_of(to_ty).ok().map(|a| a.align.abi())
=> span_lint(
cx,
MISALIGNED_TRANSMUTE,
e.span,
&format!(
"transmute from `{}` to a less-aligned type (`{}`)",
from_ty,
to_ty,
)
),
(&ty::TyRef(_, rty), &ty::TyRawPtr(ptr_ty)) => span_lint_and_then(
cx,
USELESS_TRANSMUTE,

2
tests/ui/deprecated.rs
View File

@ -9,4 +9,6 @@
#[warn(unstable_as_mut_slice)]
#[warn(misaligned_transmute)]
fn main() {}

8
tests/ui/deprecated.stderr
View File

@ -24,5 +24,11 @@ error: lint unstable_as_mut_slice has been removed: `Vec::as_mut_slice` has been
10 | #[warn(unstable_as_mut_slice)]
| ^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 4 previous errors
error: lint misaligned_transmute has been removed: this lint has been split into cast_ptr_alignment and transmute_ptr_to_ptr
--> $DIR/deprecated.rs:12:8
|
12 | #[warn(misaligned_transmute)]
| ^^^^^^^^^^^^^^^^^^^^
error: aborting due to 5 previous errors

7
tests/ui/transmute.rs
View File

@ -140,13 +140,6 @@ fn bytes_to_str(b: &[u8], mb: &mut [u8]) {
let _: &mut str = unsafe { std::mem::transmute(mb) };
}
#[warn(misaligned_transmute)]
fn misaligned_transmute() {
let _: u32 = unsafe { std::mem::transmute([0u8; 4]) }; // err
let _: u32 = unsafe { std::mem::transmute(0f32) }; // ok (alignment-wise)
let _: [u8; 4] = unsafe { std::mem::transmute(0u32) }; // ok (alignment-wise)
}
#[warn(transmute_ptr_to_ptr)]
fn transmute_ptr_to_ptr() {
let ptr = &1u32 as *const u32;

26
tests/ui/transmute.stderr
View File

@ -204,39 +204,31 @@ error: transmute from a `&mut [u8]` to a `&mut str`
140 | let _: &mut str = unsafe { std::mem::transmute(mb) };
| ^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8_mut(mb).unwrap()`
error: transmute from `[u8; 4]` to a less-aligned type (`u32`)
--> $DIR/transmute.rs:145:27
|
145 | let _: u32 = unsafe { std::mem::transmute([0u8; 4]) }; // err
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D misaligned-transmute` implied by `-D warnings`
error: transmute from a pointer to a pointer
--> $DIR/transmute.rs:156:29
--> $DIR/transmute.rs:149:29
|
156 | let _: *const f32 = std::mem::transmute(ptr);
149 | let _: *const f32 = std::mem::transmute(ptr);
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `ptr as *const f32`
|
= note: `-D transmute-ptr-to-ptr` implied by `-D warnings`
error: transmute from a pointer to a pointer
--> $DIR/transmute.rs:157:27
--> $DIR/transmute.rs:150:27
|
157 | let _: *mut f32 = std::mem::transmute(mut_ptr);
150 | let _: *mut f32 = std::mem::transmute(mut_ptr);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `mut_ptr as *mut f32`
error: transmute from a reference to a reference
--> $DIR/transmute.rs:159:23
--> $DIR/transmute.rs:152:23
|
159 | let _: &f32 = std::mem::transmute(&1u32);
152 | let _: &f32 = std::mem::transmute(&1u32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `&*(&1u32 as *const u32 as *const f32)`
error: transmute from a reference to a reference
--> $DIR/transmute.rs:160:27
--> $DIR/transmute.rs:153:27
|
160 | let _: &mut f32 = std::mem::transmute(&mut 1u32);
153 | let _: &mut f32 = std::mem::transmute(&mut 1u32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `&mut *(&mut 1u32 as *mut u32 as *mut f32)`
error: aborting due to 37 previous errors
error: aborting due to 36 previous errors