mirror of
https://github.com/servo/servo
synced 2026-05-15 03:16:47 +02:00
47c269360c
At first I was considering moving it to a procedural macro
(source-level information should be sufficient),
and started by trying to reproduce the error case
by changing `htmldivelement.rs` to use `Element` instead of `HTMLElement`
as the first field.
The output was:
```rust
error[E0308]: mismatched types
--> /home/simon/servo2/target/debug/build/script-4caa244faca7d10f/out/Bindings/HTMLDivElementBinding.rs:665:31
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665 | let _: &HTMLElement = self.as_parent();
| ^^^^^^^^^^^^^^^^ expected struct `dom::htmlelement::HTMLElement`, found struct `dom::element::Element`
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= note: expected type `&dom::htmlelement::HTMLElement`
found type `&dom::element::Element`
```
This line number is inside a generated method called `__assert_parent_type`.
As far as I can tell, any case where this lint would error is already caught
by such methods. The lint is therefore redundant and can safely be removed.
62 lines
2.0 KiB
Rust
62 lines
2.0 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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extern crate proc_macro;
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#[macro_use]
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extern crate quote;
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extern crate syn;
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use proc_macro::TokenStream;
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use syn::*;
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#[proc_macro_attribute]
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pub fn dom_struct(args: TokenStream, input: TokenStream) -> TokenStream {
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if !args.is_empty() {
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panic!("#[dom_struct] takes no arguments");
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}
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let attributes = quote! {
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#[derive(DenyPublicFields, DomObject, JSTraceable, MallocSizeOf)]
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#[must_root]
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#[repr(C)]
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};
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// Work around https://github.com/rust-lang/rust/issues/46489
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let attributes: TokenStream = attributes.to_string().parse().unwrap();
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let output: TokenStream = attributes.into_iter().chain(input.into_iter()).collect();
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let item: Item = syn::parse(output).unwrap();
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if let Item::Struct(s) = item {
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let s2 = s.clone();
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if s.generics.params.len() > 0 {
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return quote!(#s2).into();
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}
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if let Fields::Named(ref f) = s.fields {
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let f = f.named.first().expect("Must have at least one field");
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let ident = f.ident.as_ref().expect("Must have named fields");
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let name = &s.ident;
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let ty = &f.ty;
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quote! (
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#s2
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impl crate::dom::bindings::inheritance::HasParent for #name {
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type Parent = #ty;
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/// This is used in a type assertion to ensure that
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/// the source and webidls agree as to what the parent type is
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fn as_parent(&self) -> &#ty {
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&self.#ident
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}
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}
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)
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.into()
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} else {
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panic!("#[dom_struct] only applies to structs with named fields");
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}
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} else {
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panic!("#[dom_struct] only applies to structs");
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}
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}
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