educe/trait_handlers/hash/
panic.rs

1use quote::ToTokens;
2use syn::{spanned::Spanned, Meta};
3
4#[inline]
5pub(crate) fn union_without_unsafe(meta: &Meta) -> syn::Error {
6    let mut s = meta.into_token_stream().to_string();
7
8    match s.len() {
9        4 => s.push_str("(unsafe)"),
10        6 => s.insert_str(10, "unsafe"),
11        _ => unreachable!(),
12    }
13
14    syn::Error::new(
15        meta.span(),
16        format!(
17            "a union's `Hash` implementation is not precise, because it ignores the type of \
18             fields\n* If your union doesn't care about that, use `#[educe({s})]` to implement \
19             the `Hash` trait for it."
20        ),
21    )
22}