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Emit the enum discriminant separately for the Encodable macro

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This commit is contained in:
John Kåre Alsaker 2023-02-24 23:58:32 +01:00
parent 07c993eba8
commit 7de205ea3a
2 changed files with 30 additions and 29 deletions
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47
compiler/rustc_macros/src/serialize.rs
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@ -42,6 +42,12 @@ fn decodable_body(
}
let ty_name = s.ast().ident.to_string();
let decode_body = match s.variants() {
[] => {
let message = format!("`{}` has no variants to decode", ty_name);
quote! {
panic!(#message)
}
}
[vi] => vi.construct(|field, _index| decode_field(field)),
variants => {
let match_inner: TokenStream = variants
@ -139,6 +145,11 @@ fn encodable_body(
});
let encode_body = match s.variants() {
[] => {
quote! {
match *self {}
}
}
[_] => {
let encode_inner = s.each_variant(|vi| {
vi.bindings()
@ -160,6 +171,23 @@ fn encodable_body(
}
}
_ => {
let disc = {
let mut variant_idx = 0usize;
let encode_inner = s.each_variant(|_| {
let result = quote! {
#variant_idx
};
variant_idx += 1;
result
});
quote! {
let disc = match *self {
#encode_inner
};
::rustc_serialize::Encoder::emit_usize(__encoder, disc);
}
};
let mut variant_idx = 0usize;
let encode_inner = s.each_variant(|vi| {
let encode_fields: TokenStream = vi
@ -176,26 +204,11 @@ fn encodable_body(
result
})
.collect();
let result = if !vi.bindings().is_empty() {
quote! {
::rustc_serialize::Encoder::emit_enum_variant(
__encoder,
#variant_idx,
|__encoder| { #encode_fields }
)
}
} else {
quote! {
::rustc_serialize::Encoder::emit_fieldless_enum_variant::<#variant_idx>(
__encoder,
)
}
};
variant_idx += 1;
result
encode_fields
});
quote! {
#disc
match *self {
#encode_inner
}