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Merge pull request #131 from cormacrelf/bad-derive-default

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Manually implement Default for *GroupStorage
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Niko Matsakis 2019-01-25 11:01:01 -05:00 committed by GitHub
commit 1b04ac19ff
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1 changed files with 13 additions and 1 deletions
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14
components/salsa-macros/src/query_group.rs
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@ -135,6 +135,7 @@ pub(crate) fn query_group(args: TokenStream, input: TokenStream) -> TokenStream
let mut query_descriptor_variants = proc_macro2::TokenStream::new();
let mut query_descriptor_maybe_change = proc_macro2::TokenStream::new();
let mut storage_fields = proc_macro2::TokenStream::new();
let mut storage_defaults = proc_macro2::TokenStream::new();
for query in &queries {
let key_names: &Vec<_> = &(0..query.keys.len())
.map(|i| Ident::new(&format!("key{}", i), Span::call_site()))
@ -221,6 +222,7 @@ pub(crate) fn query_group(args: TokenStream, input: TokenStream) -> TokenStream
storage_fields.extend(quote! {
pub #fn_name: <#qt as salsa::Query<DB__>>::Storage,
});
storage_defaults.extend(quote! { #fn_name: Default::default(), });
}
// Emit the trait itself.
@ -366,12 +368,22 @@ pub(crate) fn query_group(args: TokenStream, input: TokenStream) -> TokenStream
}
// Emit query group storage struct
// It would derive Default, but then all database structs would have to implement Default
// as the derived version includes an unused `+ Default` constraint.
output.extend(quote! {
#[derive(Default)]
#trait_vis struct #group_storage<DB__: #trait_name> {
#storage_fields
}
impl<DB__: #trait_name> Default for #group_storage<DB__> {
#[inline]
fn default() -> Self {
#group_storage {
#storage_defaults
}
}
}
impl<DB__> #group_storage<DB__>
where
DB__: #trait_name,