pin_init_internal/
pinned_drop.rs

1// SPDX-License-Identifier: Apache-2.0 OR MIT
2
3use proc_macro2::TokenStream;
4use quote::quote;
5use syn::{parse::Nothing, parse_quote, spanned::Spanned, ImplItem, ItemImpl, Token};
6
7use crate::diagnostics::{DiagCtxt, ErrorGuaranteed};
8
9pub(crate) fn pinned_drop(
10    _args: Nothing,
11    mut input: ItemImpl,
12    dcx: &mut DiagCtxt,
13) -> Result<TokenStream, ErrorGuaranteed> {
14    if let Some(unsafety) = input.unsafety {
15        dcx.error(unsafety, "implementing `PinnedDrop` is safe");
16    }
17    input.unsafety = Some(Token![unsafe](input.impl_token.span));
18    match &mut input.trait_ {
19        Some((not, path, _for)) => {
20            if let Some(not) = not {
21                dcx.error(not, "cannot implement `!PinnedDrop`");
22            }
23            for (seg, expected) in path
24                .segments
25                .iter()
26                .rev()
27                .zip(["PinnedDrop", "pin_init", ""])
28            {
29                if expected.is_empty() || seg.ident != expected {
30                    dcx.error(seg, "bad import path for `PinnedDrop`");
31                }
32                if !seg.arguments.is_none() {
33                    dcx.error(&seg.arguments, "unexpected arguments for `PinnedDrop` path");
34                }
35            }
36            *path = parse_quote!(::pin_init::PinnedDrop);
37        }
38        None => {
39            let span = input
40                .impl_token
41                .span
42                .join(input.self_ty.span())
43                .unwrap_or(input.impl_token.span);
44            dcx.error(
45                span,
46                "expected `impl ... PinnedDrop for ...`, got inherent impl",
47            );
48        }
49    }
50    for item in &mut input.items {
51        if let ImplItem::Fn(fn_item) = item {
52            if fn_item.sig.ident == "drop" {
53                fn_item
54                    .sig
55                    .inputs
56                    .push(parse_quote!(_: ::pin_init::__internal::OnlyCallFromDrop));
57            }
58        }
59    }
60    Ok(quote!(#input))
61}
pin_init_internal/pinned_drop.rs

pin_init_internal/
pinned_drop.rs
