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Implement #[error(fmt = ...)]

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David Tolnay 2024-11-04 23:20:03 -05:00
parent 5e4b7a5117
commit ba9af4522e
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11 changed files with 200 additions and 27 deletions
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32
impl/src/expand.rs
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@ -404,19 +404,23 @@ fn impl_enum(input: Enum) -> TokenStream {
};
let arms = input.variants.iter().map(|variant| {
let mut display_implied_bounds = Set::new();
let display = match &variant.attrs.display {
Some(display) => {
display_implied_bounds.clone_from(&display.implied_bounds);
display.to_token_stream()
}
None => {
let only_field = match &variant.fields[0].member {
MemberUnraw::Named(ident) => ident.to_local(),
MemberUnraw::Unnamed(index) => format_ident!("_{}", index),
};
display_implied_bounds.insert((0, Trait::Display));
quote!(::core::fmt::Display::fmt(#only_field, __formatter))
}
let display = if let Some(display) = &variant.attrs.display {
display_implied_bounds.clone_from(&display.implied_bounds);
display.to_token_stream()
} else if let Some(fmt) = &variant.attrs.fmt {
let fmt_path = &fmt.path;
let vars = variant.fields.iter().map(|field| match &field.member {
MemberUnraw::Named(ident) => ident.to_local(),
MemberUnraw::Unnamed(index) => format_ident!("_{}", index),
});
quote!(#fmt_path(#(#vars,)* __formatter))
} else {
let only_field = match &variant.fields[0].member {
MemberUnraw::Named(ident) => ident.to_local(),
MemberUnraw::Unnamed(index) => format_ident!("_{}", index),
};
display_implied_bounds.insert((0, Trait::Display));
quote!(::core::fmt::Display::fmt(#only_field, __formatter))
};
for (field, bound) in display_implied_bounds {
let field = &variant.fields[field];
@ -494,7 +498,7 @@ fn fields_pat(fields: &[Field]) -> TokenStream {
Some(MemberUnraw::Named(_)) => quote!({ #(#members),* }),
Some(MemberUnraw::Unnamed(_)) => {
let vars = members.map(|member| match member {
MemberUnraw::Unnamed(member) => format_ident!("_{}", member),
MemberUnraw::Unnamed(index) => format_ident!("_{}", index),
MemberUnraw::Named(_) => unreachable!(),
});
quote!((#(#vars),*))