add test for casting pointer to union with unsized tail

This commit is contained in:
Lukas Markeffsky 2024-03-19 13:57:31 +01:00
parent 91b87c4f45
commit 7b21c1a457
2 changed files with 37 additions and 0 deletions

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@ -0,0 +1,14 @@
// Regression test for https://github.com/rust-lang/rust/issues/122581
// This used to ICE, because the union was unsized and the pointer casting code
// assumed that non-struct ADTs must be sized.
union Union {
val: std::mem::ManuallyDrop<[u8]>,
//~^ ERROR the size for values of type `[u8]` cannot be known at compilation time
}
fn cast(ptr: *const ()) -> *const Union {
ptr as _
}
fn main() {}

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error[E0277]: the size for values of type `[u8]` cannot be known at compilation time
--> $DIR/unsized-union-ice.rs:6:10
|
LL | val: std::mem::ManuallyDrop<[u8]>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
|
= help: within `ManuallyDrop<[u8]>`, the trait `Sized` is not implemented for `[u8]`, which is required by `ManuallyDrop<[u8]>: Sized`
note: required because it appears within the type `ManuallyDrop<[u8]>`
--> $SRC_DIR/core/src/mem/manually_drop.rs:LL:COL
= note: no field of a union may have a dynamically sized type
= help: change the field's type to have a statically known size
help: borrowed types always have a statically known size
|
LL | val: &std::mem::ManuallyDrop<[u8]>,
| +
help: the `Box` type always has a statically known size and allocates its contents in the heap
|
LL | val: Box<std::mem::ManuallyDrop<[u8]>>,
| ++++ +
error: aborting due to 1 previous error
For more information about this error, try `rustc --explain E0277`.