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Auto merge of #8612 - SabrinaJewson:suggest-from-utf8-unchecked-in-const, r=flip1995

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Suggest from_utf8_unchecked in const contexts

Unfortunately I couldn't figure out how to check whether a given expression is in an `unsafe` context or not, so I just unconditionally emit the wrapping `unsafe {}` block in the suggestion. If there is an easy way to get it to work better then I would love to hear it.

changelog: Suggest `from_utf8_unchecked` instead of `from_utf8` in const contexts for ``[`transmute_bytes_to_str`]``

refs: #8379
This commit is contained in:
bors 2022-04-06 09:32:51 +00:00
commit cf1e2e9c1c
3 changed files with 24 additions and 13 deletions
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14
clippy_lints/src/transmute/transmute_ref_to_ref.rs
View file

@ -32,18 +32,20 @@ pub(super) fn check<'tcx>(
""
};
let snippet = snippet(cx, arg.span, "..");
span_lint_and_sugg(
cx,
TRANSMUTE_BYTES_TO_STR,
e.span,
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
"consider using",
format!(
"std::str::from_utf8{}({}).unwrap()",
postfix,
snippet(cx, arg.span, ".."),
),
Applicability::Unspecified,
if const_context {
format!("std::str::from_utf8_unchecked{postfix}({snippet})")
} else {
format!("std::str::from_utf8{postfix}({snippet}).unwrap()")
},
Applicability::MaybeIncorrect,
);
triggered = true;
} else {

7
tests/ui/transmute.rs
View file

@ -134,9 +134,12 @@ mod num_to_bytes {
}
}
fn bytes_to_str(b: &[u8], mb: &mut [u8]) {
let _: &str = unsafe { std::mem::transmute(b) };
fn bytes_to_str(mb: &mut [u8]) {
const B: &[u8] = b"";
let _: &str = unsafe { std::mem::transmute(B) };
let _: &mut str = unsafe { std::mem::transmute(mb) };
const _: &str = unsafe { std::mem::transmute(B) };
}
fn main() {}

16
tests/ui/transmute.stderr
View file

@ -227,18 +227,24 @@ 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:138:28
--> $DIR/transmute.rs:140:28
|
LL | let _: &str = unsafe { std::mem::transmute(b) };
| ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8(b).unwrap()`
LL | let _: &str = unsafe { std::mem::transmute(B) };
| ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8(B).unwrap()`
|
= note: `-D clippy::transmute-bytes-to-str` implied by `-D warnings`
error: transmute from a `&mut [u8]` to a `&mut str`
--> $DIR/transmute.rs:139:32
--> $DIR/transmute.rs:141:32
|
LL | let _: &mut str = unsafe { std::mem::transmute(mb) };
| ^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8_mut(mb).unwrap()`
error: aborting due to 38 previous errors
error: transmute from a `&[u8]` to a `&str`
--> $DIR/transmute.rs:142:30
|
LL | const _: &str = unsafe { std::mem::transmute(B) };
| ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8_unchecked(B)`
error: aborting due to 39 previous errors