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Add special-case for [T, 0] in dropck

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This commit is contained in:
Bryanskiy 2024-07-31 15:55:56 +03:00
parent 595316b400
commit 34fcf92ea0
2 changed files with 32 additions and 2 deletions
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11
compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs
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@ -42,8 +42,15 @@ pub fn trivial_dropck_outlives<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> bool {
| ty::Foreign(..)
| ty::Error(_) => true,
// `T is PAT`, `[T; N]`, and `[T]` have same properties as T.
ty::Pat(ty, _) | ty::Array(ty, _) | ty::Slice(ty) => trivial_dropck_outlives(tcx, *ty),
// `T is PAT` and `[T]` have same properties as T.
ty::Pat(ty, _) | ty::Slice(ty) => trivial_dropck_outlives(tcx, *ty),
ty::Array(ty, size) => {
// Empty array never has a dtor. See issue #110288.
match size.try_to_target_usize(tcx) {
Some(0) => true,
_ => trivial_dropck_outlives(tcx, *ty),
}
}
// (T1..Tn) and closures have same properties as T1..Tn --
// check if *all* of them are trivial.

23
tests/ui/dropck/dropck-empty-array.rs Normal file
View File

@ -0,0 +1,23 @@
//@ run-pass
#[allow(dead_code)]
struct Struct<'s>(&'s str);
impl<'s> Drop for Struct<'s> {
fn drop(&mut self) {}
}
fn to_array_zero<T>(_: T) -> [T; 0] {
[]
}
pub fn array_zero_in_tuple() {
let mut x = ([], String::new());
{
let s = String::from("temporary");
let p = Struct(&s);
x.0 = to_array_zero(p);
}
}
fn main() {}