bjoernager/rust
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Auto merge of #119478 - bjorn3:no_serialize_specialization, r=wesleywiser

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Avoid specialization in the metadata serialization code

With the exception of a perf-only specialization for byte slices and byte vectors.

This uses the same trick of introducing a new trait and having the Encodable and Decodable derives add a bound to it as used for TyEncoder/TyDecoder. The new code is clearer about which encoder/decoder uses which impl and it reduces the dependency of rustc on specialization, making it easier to remove support for specialization entirely or turn it into a construct that is only allowed for perf optimizations if we decide to do this.
This commit is contained in:
bors 2024-01-06 09:56:00 +00:00
commit e21f4cd98f
24 changed files with 478 additions and 400 deletions
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2
compiler/rustc_macros/src/lib.rs
View file

@ -56,6 +56,8 @@ decl_derive!(
hash_stable::hash_stable_no_context_derive
);
decl_derive!([Decodable_Generic] => serialize::decodable_generic_derive);
decl_derive!([Encodable_Generic] => serialize::encodable_generic_derive);
decl_derive!([Decodable] => serialize::decodable_derive);
decl_derive!([Encodable] => serialize::encodable_derive);
decl_derive!([TyDecodable] => serialize::type_decodable_derive);

16
compiler/rustc_macros/src/serialize.rs
View file

@ -31,6 +31,14 @@ pub fn meta_decodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2:
}
pub fn decodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
let decoder_ty = quote! { __D };
s.add_impl_generic(parse_quote! {#decoder_ty: ::rustc_span::SpanDecoder});
s.add_bounds(synstructure::AddBounds::Generics);
decodable_body(s, decoder_ty)
}
pub fn decodable_generic_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
let decoder_ty = quote! { __D };
s.add_impl_generic(parse_quote! {#decoder_ty: ::rustc_serialize::Decoder});
s.add_bounds(synstructure::AddBounds::Generics);
@ -129,6 +137,14 @@ pub fn meta_encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2:
}
pub fn encodable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
let encoder_ty = quote! { __E };
s.add_impl_generic(parse_quote! { #encoder_ty: ::rustc_span::SpanEncoder});
s.add_bounds(synstructure::AddBounds::Generics);
encodable_body(s, encoder_ty, false)
}
pub fn encodable_generic_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::TokenStream {
let encoder_ty = quote! { __E };
s.add_impl_generic(parse_quote! { #encoder_ty: ::rustc_serialize::Encoder});
s.add_bounds(synstructure::AddBounds::Generics);