Auto merge of #12216 - bpandreotti:redundant-type-annotations-fix, r=Jarcho

Fix false positive in `redundant_type_annotations` lint

This PR changes the `redundant_type_annotations` lint to allow slice type annotations (i.e., `&[u8]`) for byte string literals. It will still consider _array_ type annotations (i.e., `&[u8; 4]`) as redundant. The reasoning behind this is that the type of byte string literals is by default a reference to an array, but, by using a type annotation, you can force it to be a slice. For example:
```rust
let a: &[u8; 4] = b"test";
let b: &[u8] = b"test";
```

Now, the type annotation for `a` will still be linted (as it is still redundant), but the type annotation for `b` will not.

Fixes #12212.

changelog: [`redundant_type_annotations`]: Fix false positive with byte string literals
This commit is contained in:
bors 2024-02-07 16:02:28 +00:00
commit 08c8cd5014
3 changed files with 18 additions and 4 deletions

View file

@ -188,7 +188,6 @@ impl LateLintPass<'_> for RedundantTypeAnnotations {
match init_lit.node {
// In these cases the annotation is redundant
LitKind::Str(..)
| LitKind::ByteStr(..)
| LitKind::Byte(..)
| LitKind::Char(..)
| LitKind::Bool(..)
@ -202,6 +201,16 @@ impl LateLintPass<'_> for RedundantTypeAnnotations {
}
},
LitKind::Err => (),
LitKind::ByteStr(..) => {
// We only lint if the type annotation is an array type (e.g. &[u8; 4]).
// If instead it is a slice (e.g. &[u8]) it may not be redundant, so we
// don't lint.
if let hir::TyKind::Ref(_, mut_ty) = ty.kind
&& matches!(mut_ty.ty.kind, hir::TyKind::Array(..))
{
span_lint(cx, REDUNDANT_TYPE_ANNOTATIONS, local.span, "redundant type annotation");
}
},
}
},
_ => (),

View file

@ -196,13 +196,18 @@ fn test_simple_types() {
let _var: &str = "test";
//~^ ERROR: redundant type annotation
let _var: &[u8] = b"test";
let _var: &[u8; 4] = b"test";
//~^ ERROR: redundant type annotation
let _var: bool = false;
//~^ ERROR: redundant type annotation
}
fn issue12212() {
// This should not be linted
let _var: &[u8] = b"test";
}
fn issue11190() {}
fn main() {}

View file

@ -94,8 +94,8 @@ LL | let _var: &str = "test";
error: redundant type annotation
--> $DIR/redundant_type_annotations.rs:199:5
|
LL | let _var: &[u8] = b"test";
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | let _var: &[u8; 4] = b"test";
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: redundant type annotation
--> $DIR/redundant_type_annotations.rs:202:5