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Support derive(Default) on structs

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This commit is contained in:
David Tolnay 2020-11-27 17:22:35 -08:00
parent b600e4f348
commit a6a9e94e08
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GPG Key ID: F9BA143B95FF6D82
3 changed files with 32 additions and 1 deletions
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19
macro/src/derive.rs
View File

@ -14,6 +14,7 @@ pub fn expand_struct(strct: &Struct, actual_derives: &mut Option<TokenStream>) -
Trait::Copy => expanded.extend(struct_copy(strct, span)),
Trait::Clone => expanded.extend(struct_clone(strct, span)),
Trait::Debug => expanded.extend(struct_debug(strct, span)),
Trait::Default => expanded.extend(struct_default(strct, span)),
Trait::Eq => traits.push(quote_spanned!(span=> ::std::cmp::Eq)),
Trait::Ord => expanded.extend(struct_ord(strct, span)),
Trait::PartialEq => traits.push(quote_spanned!(span=> ::std::cmp::PartialEq)),
@ -50,6 +51,7 @@ pub fn expand_enum(enm: &Enum, actual_derives: &mut Option<TokenStream>) -> Toke
has_clone = true;
}
Trait::Debug => expanded.extend(enum_debug(enm, span)),
Trait::Default => unreachable!(),
Trait::Eq => {
traits.push(quote_spanned!(span=> ::std::cmp::Eq));
has_eq = true;
@ -136,6 +138,23 @@ fn struct_debug(strct: &Struct, span: Span) -> TokenStream {
}
}
fn struct_default(strct: &Struct, span: Span) -> TokenStream {
let ident = &strct.name.rust;
let fields = strct.fields.iter().map(|field| &field.ident);
quote_spanned! {span=>
impl ::std::default::Default for #ident {
fn default() -> Self {
#ident {
#(
#fields: ::std::default::Default::default(),
)*
}
}
}
}
}
fn struct_ord(strct: &Struct, span: Span) -> TokenStream {
let ident = &strct.name.rust;
let fields = strct.fields.iter().map(|field| &field.ident);

11
syntax/check.rs
View File

@ -3,7 +3,7 @@ use crate::syntax::report::Errors;
use crate::syntax::types::TrivialReason;
use crate::syntax::{
error, ident, Api, Array, Enum, ExternFn, ExternType, Impl, Lang, Receiver, Ref, Signature,
SliceRef, Struct, Ty1, Type, Types,
SliceRef, Struct, Trait, Ty1, Type, Types,
};
use proc_macro2::{Delimiter, Group, Ident, TokenStream};
use quote::{quote, ToTokens};
@ -256,6 +256,15 @@ fn check_api_enum(cx: &mut Check, enm: &Enum) {
"explicit #[repr(...)] is required for enum without any variants",
);
}
for derive in &enm.derives {
if derive.what == Trait::Default {
cx.error(
derive,
"derive(Default) on shared enums is not supported yet",
);
}
}
}
fn check_api_type(cx: &mut Check, ety: &ExternType) {

3
syntax/derive.rs
View File

@ -11,6 +11,7 @@ pub enum Trait {
Clone,
Copy,
Debug,
Default,
Eq,
Ord,
PartialEq,
@ -23,6 +24,7 @@ impl Derive {
"Clone" => Trait::Clone,
"Copy" => Trait::Copy,
"Debug" => Trait::Debug,
"Default" => Trait::Default,
"Eq" => Trait::Eq,
"Ord" => Trait::Ord,
"PartialEq" => Trait::PartialEq,
@ -46,6 +48,7 @@ impl AsRef<str> for Trait {
Trait::Clone => "Clone",
Trait::Copy => "Copy",
Trait::Debug => "Debug",
Trait::Default => "Default",
Trait::Eq => "Eq",
Trait::Ord => "Ord",
Trait::PartialEq => "PartialEq",