Closed
Description
Code
use std::marker::PhantomData;
pub enum Empty {}
struct Test<A, B: ?Sized> {
phantom: PhantomData<(A, B)>,
}
fn main() {
let x: Test<Empty, [usize]>;
}Error output
Compiling playground v0.0.1 (/playground)
warning: unused variable: `x`
--> src/main.rs:10:9
|
10 | let x: Test<Empty, [usize]>;
| ^ help: if this is intentional, prefix it with an underscore: `_x`
|
= note: `#[warn(unused_variables)]` on by default
thread 'rustc' panicked at 'assertion failed: layout.abi.is_uninhabited()', compiler/rustc_middle/src/ty/layout.rs:205:21
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
error: internal compiler error: unexpected panic
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md
note: rustc 1.50.0 (cb75ad5db 2021-02-10) running on x86_64-unknown-linux-gnu
note: compiler flags: -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2 --crate-type bin
note: some of the compiler flags provided by cargo are hidden
query stack during panic:
#0 [layout_raw] computing layout of `(Empty, [usize])`
end of query stack
warning: 1 warning emitted
error: could not compile `playground`
To learn more, run the command again with --verbose.
The error seems to only occur when using an uninhabited type with a dynamically sized one in a tuple.
Inhabited types with dynamically sized and uninhabited types with sized types both work.
A simple workaround for now is to box the DST in the PhantomData.
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment