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fix: let-and-return suggests invalid cast (#16135) #16147

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fix: let-and-return suggests invalid cast (#16135) #16147

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5 changes: 4 additions & 1 deletion clippy_lints/src/returns/let_and_return.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,10 @@ pub(super) fn check_block<'tcx>(cx: &LateContext<'tcx>, block: &'tcx Block<'_>)
} else {
format!("({src})")
}
} else if !cx.typeck_results().expr_adjustments(retexpr).is_empty() {
} else if !cx.typeck_results().expr_adjustments(retexpr).is_empty()
// Do not suggest 'as _' for raw pointers; it's an invalid cast
&& !cx.typeck_results().expr_ty_adjusted(retexpr).is_raw_ptr()
{
if has_enclosing_paren(&src) {
format!("{src} as _")
} else {
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11 changes: 11 additions & 0 deletions tests/ui/let_and_return.edition2021.fixed
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Expand Up @@ -271,4 +271,15 @@ fn issue15987() -> i32 {
r
}

// https://github.com/rust-lang/rust-clippy/issues/16135
mod issue16135 {
struct S;
trait T {}
impl T for S {}

fn f(x: *const S) -> *const dyn T {
Clone::clone(&x) as _
}
}

fn main() {}
11 changes: 11 additions & 0 deletions tests/ui/let_and_return.edition2024.fixed
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Expand Up @@ -271,4 +271,15 @@ fn issue15987() -> i32 {
r
}

// https://github.com/rust-lang/rust-clippy/issues/16135
mod issue16135 {
struct S;
trait T {}
impl T for S {}

fn f(x: *const S) -> *const dyn T {
Clone::clone(&x) as _
}
}

fn main() {}
11 changes: 11 additions & 0 deletions tests/ui/let_and_return.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -271,4 +271,15 @@ fn issue15987() -> i32 {
r
}

// https://github.com/rust-lang/rust-clippy/issues/16135
mod issue16135 {
struct S;
trait T {}
impl T for S {}

fn f(x: *const S) -> *const dyn T {
Clone::clone(&x) as _
}
}
Comment on lines +275 to +283
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@Jarcho Jarcho Dec 12, 2025

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This doesn't test the lint. The function body should be:

let x = Clone::clone(&x);
x

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@ErinvanderVeen ErinvanderVeen Dec 12, 2025

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You're absolutely right. I'll try to get to this asap.

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@ErinvanderVeen ErinvanderVeen Dec 15, 2025

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No, that doesn't work.

struct S;
trait T {}
impl T for S {}

fn f(x: *const S) -> *const dyn T {
    Clone::clone(&x) as _
}

Doesn't actually create an error, so the lint was valid.

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@Jarcho Jarcho Dec 15, 2025

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That not cause a lint warning is why you need to change the test. Right now the test contains what the code should be after rustfix runs, but the test needs to make sure we don't make a broken suggestion. Hence you need to change the function's body to what I said earlier so that it will actually trigger let_and_return.

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@ErinvanderVeen ErinvanderVeen Dec 16, 2025 •
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That, I understand, but I'd love to be able to reproduce the error from the original issue in the test. This test doesn't have that error.


fn main() {}