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Add bounds for associated types in derive macro

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This commit is contained in:
hkalbasi 2023-04-07 19:33:14 +03:30
parent 972f1313eb
commit c54cb88950
5 changed files with 187 additions and 30 deletions
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131
crates/hir-expand/src/builtin_derive_macro.rs
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@ -1,11 +1,12 @@
//! Builtin derives.
use base_db::{CrateOrigin, LangCrateOrigin};
use std::collections::HashSet;
use tracing::debug;
use crate::tt::{self, TokenId};
use syntax::{
ast::{self, AstNode, HasGenericParams, HasModuleItem, HasName},
ast::{self, AstNode, HasGenericParams, HasModuleItem, HasName, HasTypeBounds, PathType},
match_ast,
};
@ -60,8 +61,11 @@ pub fn find_builtin_derive(ident: &name::Name) -> Option<BuiltinDeriveExpander>
struct BasicAdtInfo {
name: tt::Ident,
/// `Some(ty)` if it's a const param of type `ty`, `None` if it's a type param.
param_types: Vec<Option<tt::Subtree>>,
/// first field is the name, and
/// second field is `Some(ty)` if it's a const param of type `ty`, `None` if it's a type param.
/// third fields is where bounds, if any
param_types: Vec<(tt::Subtree, Option<tt::Subtree>, Option<tt::Subtree>)>,
associated_types: Vec<tt::Subtree>,
}
fn parse_adt(tt: &tt::Subtree) -> Result<BasicAdtInfo, ExpandError> {
@ -86,18 +90,28 @@ fn parse_adt(tt: &tt::Subtree) -> Result<BasicAdtInfo, ExpandError> {
},
}
};
let name = name.ok_or_else(|| {
debug!("parsed item has no name");
ExpandError::Other("missing name".into())
})?;
let name_token_id =
token_map.token_by_range(name.syntax().text_range()).unwrap_or_else(TokenId::unspecified);
let name_token = tt::Ident { span: name_token_id, text: name.text().into() };
let mut param_type_set: HashSet<String> = HashSet::new();
let param_types = params
.into_iter()
.flat_map(|param_list| param_list.type_or_const_params())
.map(|param| {
if let ast::TypeOrConstParam::Const(param) = param {
let name = {
let this = param.name();
match this {
Some(x) => {
param_type_set.insert(x.to_string());
mbe::syntax_node_to_token_tree(x.syntax()).0
}
None => tt::Subtree::empty(),
}
};
let bounds = match &param {
ast::TypeOrConstParam::Type(x) => {
x.type_bound_list().map(|x| mbe::syntax_node_to_token_tree(x.syntax()).0)
}
ast::TypeOrConstParam::Const(_) => None,
};
let ty = if let ast::TypeOrConstParam::Const(param) = param {
let ty = param
.ty()
.map(|ty| mbe::syntax_node_to_token_tree(ty.syntax()).0)
@ -105,27 +119,97 @@ fn parse_adt(tt: &tt::Subtree) -> Result<BasicAdtInfo, ExpandError> {
Some(ty)
} else {
None
}
};
(name, ty, bounds)
})
.collect();
Ok(BasicAdtInfo { name: name_token, param_types })
let is_associated_type = |p: &PathType| {
if let Some(p) = p.path() {
if let Some(parent) = p.qualifier() {
if let Some(x) = parent.segment() {
if let Some(x) = x.path_type() {
if let Some(x) = x.path() {
if let Some(pname) = x.as_single_name_ref() {
if param_type_set.contains(&pname.to_string()) {
// <T as Trait>::Assoc
return true;
}
}
}
}
}
if let Some(pname) = parent.as_single_name_ref() {
if param_type_set.contains(&pname.to_string()) {
// T::Assoc
return true;
}
}
}
}
false
};
let associated_types = node
.descendants()
.filter_map(PathType::cast)
.filter(is_associated_type)
.map(|x| mbe::syntax_node_to_token_tree(x.syntax()).0)
.collect::<Vec<_>>();
let name = name.ok_or_else(|| {
debug!("parsed item has no name");
ExpandError::Other("missing name".into())
})?;
let name_token_id =
token_map.token_by_range(name.syntax().text_range()).unwrap_or_else(TokenId::unspecified);
let name_token = tt::Ident { span: name_token_id, text: name.text().into() };
Ok(BasicAdtInfo { name: name_token, param_types, associated_types })
}
/// Given that we are deriving a trait `DerivedTrait` for a type like:
///
/// ```ignore (only-for-syntax-highlight)
/// struct Struct<'a, ..., 'z, A, B: DeclaredTrait, C, ..., Z> where C: WhereTrait {
/// a: A,
/// b: B::Item,
/// b1: <B as DeclaredTrait>::Item,
/// c1: <C as WhereTrait>::Item,
/// c2: Option<<C as WhereTrait>::Item>,
/// ...
/// }
/// ```
///
/// create an impl like:
///
/// ```ignore (only-for-syntax-highlight)
/// impl<'a, ..., 'z, A, B: DeclaredTrait, C, ... Z> where
/// C: WhereTrait,
/// A: DerivedTrait + B1 + ... + BN,
/// B: DerivedTrait + B1 + ... + BN,
/// C: DerivedTrait + B1 + ... + BN,
/// B::Item: DerivedTrait + B1 + ... + BN,
/// <C as WhereTrait>::Item: DerivedTrait + B1 + ... + BN,
/// ...
/// {
/// ...
/// }
/// ```
///
/// where B1, ..., BN are the bounds given by `bounds_paths`.'. Z is a phantom type, and
/// therefore does not get bound by the derived trait.
fn expand_simple_derive(tt: &tt::Subtree, trait_path: tt::Subtree) -> ExpandResult<tt::Subtree> {
let info = match parse_adt(tt) {
Ok(info) => info,
Err(e) => return ExpandResult::with_err(tt::Subtree::empty(), e),
};
let mut where_block = vec![];
let (params, args): (Vec<_>, Vec<_>) = info
.param_types
.into_iter()
.enumerate()
.map(|(idx, param_ty)| {
let ident = tt::Leaf::Ident(tt::Ident {
span: tt::TokenId::unspecified(),
text: format!("T{idx}").into(),
});
.map(|(ident, param_ty, bound)| {
let ident_ = ident.clone();
if let Some(b) = bound {
let ident = ident.clone();
where_block.push(quote! { #ident : #b , });
}
if let Some(ty) = param_ty {
(quote! { const #ident : #ty , }, quote! { #ident_ , })
} else {
@ -134,9 +218,16 @@ fn expand_simple_derive(tt: &tt::Subtree, trait_path: tt::Subtree) -> ExpandResu
}
})
.unzip();
where_block.extend(info.associated_types.iter().map(|x| {
let x = x.clone();
let bound = trait_path.clone();
quote! { #x : #bound , }
}));
let name = info.name;
let expanded = quote! {
impl < ##params > #trait_path for #name < ##args > {}
impl < ##params > #trait_path for #name < ##args > where ##where_block {}
};
ExpandResult::ok(expanded)
}