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Avoid generating ref patterns for fields of packed remote struct

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This commit is contained in:
David Tolnay 2021-08-23 10:17:44 -07:00
parent 14accf7518
commit 54102ee7d0
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GPG Key ID: F9BA143B95FF6D82
3 changed files with 19 additions and 9 deletions
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7
serde_derive/src/de.rs
View File

@ -36,7 +36,7 @@ pub fn expand_derive_deserialize(
let impl_block = if let Some(remote) = cont.attrs.remote() {
let vis = &input.vis;
let used = pretend::pretend_used(&cont);
let used = pretend::pretend_used(&cont, params.is_packed);
quote! {
impl #de_impl_generics #ident #ty_generics #where_clause {
#vis fn deserialize<__D>(__deserializer: __D) -> #serde::__private::Result<#remote #ty_generics, __D::Error>
@ -125,6 +125,9 @@ struct Parameters {
/// At least one field has a serde(getter) attribute, implying that the
/// remote type has a private field.
has_getter: bool,
/// Type has a repr(packed) attribute.
is_packed: bool,
}
impl Parameters {
@ -137,6 +140,7 @@ impl Parameters {
let borrowed = borrowed_lifetimes(cont);
let generics = build_generics(cont, &borrowed);
let has_getter = cont.data.has_getter();
let is_packed = cont.attrs.is_packed();
Parameters {
local,
@ -144,6 +148,7 @@ impl Parameters {
generics,
borrowed,
has_getter,
is_packed,
}
}

19
serde_derive/src/pretend.rs
View File

@ -20,8 +20,8 @@ use internals::ast::{Container, Data, Field, Style};
// 8 | enum EnumDef { V }
// | ^
//
pub fn pretend_used(cont: &Container) -> TokenStream {
let pretend_fields = pretend_fields_used(cont);
pub fn pretend_used(cont: &Container, is_packed: bool) -> TokenStream {
let pretend_fields = pretend_fields_used(cont, is_packed);
let pretend_variants = pretend_variants_used(cont);
quote! {
@ -48,7 +48,7 @@ pub fn pretend_used(cont: &Container) -> TokenStream {
// The `ref` is important in case the user has written a Drop impl on their
// type. Rust does not allow destructuring a struct or enum that has a Drop
// impl.
fn pretend_fields_used(cont: &Container) -> TokenStream {
fn pretend_fields_used(cont: &Container, is_packed: bool) -> TokenStream {
let type_ident = &cont.ident;
let (_, ty_generics, _) = cont.generics.split_for_impl();
@ -58,14 +58,14 @@ fn pretend_fields_used(cont: &Container) -> TokenStream {
.filter_map(|variant| match variant.style {
Style::Struct => {
let variant_ident = &variant.ident;
let pat = struct_pattern(&variant.fields);
let pat = struct_pattern(&variant.fields, is_packed);
Some(quote!(#type_ident::#variant_ident #pat))
}
_ => None,
})
.collect::<Vec<_>>(),
Data::Struct(Style::Struct, fields) => {
let pat = struct_pattern(fields);
let pat = struct_pattern(fields, is_packed);
vec![quote!(#type_ident #pat)]
}
Data::Struct(_, _) => {
@ -132,9 +132,14 @@ fn pretend_variants_used(cont: &Container) -> TokenStream {
quote!(#(#cases)*)
}
fn struct_pattern(fields: &[Field]) -> TokenStream {
fn struct_pattern(fields: &[Field], is_packed: bool) -> TokenStream {
let members = fields.iter().map(|field| &field.member);
let placeholders =
(0..fields.len()).map(|i| Ident::new(&format!("__v{}", i), Span::call_site()));
quote!({ #(#members: ref #placeholders),* })
let take_reference = if is_packed {
None
} else {
Some(quote!(ref))
};
quote!({ #(#members: #take_reference #placeholders),* })
}

2
serde_derive/src/ser.rs
View File

@ -30,7 +30,7 @@ pub fn expand_derive_serialize(
let impl_block = if let Some(remote) = cont.attrs.remote() {
let vis = &input.vis;
let used = pretend::pretend_used(&cont);
let used = pretend::pretend_used(&cont, params.is_packed);
quote! {
impl #impl_generics #ident #ty_generics #where_clause {
#vis fn serialize<__S>(__self: &#remote #ty_generics, __serializer: __S) -> #serde::__private::Result<__S::Ok, __S::Error>