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Support the new CoercePointee derive

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This commit is contained in:
Chayim Refael Friedman 2025-01-02 19:05:07 +02:00
parent 061d257e90
commit ce323627c5
8 changed files with 767 additions and 63 deletions
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624
crates/hir-expand/src/builtin/derive_macro.rs
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@ -1,9 +1,10 @@
//! Builtin derives.
use intern::sym;
use itertools::izip;
use itertools::{izip, Itertools};
use parser::SyntaxKind;
use rustc_hash::FxHashSet;
use span::{MacroCallId, Span};
use span::{MacroCallId, Span, SyntaxContextId};
use stdx::never;
use syntax_bridge::DocCommentDesugarMode;
use tracing::debug;
@ -16,8 +17,12 @@ use crate::{
span_map::ExpansionSpanMap,
tt, ExpandError, ExpandResult,
};
use syntax::ast::{
self, AstNode, FieldList, HasAttrs, HasGenericParams, HasModuleItem, HasName, HasTypeBounds,
use syntax::{
ast::{
self, edit_in_place::GenericParamsOwnerEdit, make, AstNode, FieldList, HasAttrs,
HasGenericArgs, HasGenericParams, HasModuleItem, HasName, HasTypeBounds,
},
ted,
};
macro_rules! register_builtin {
@ -67,13 +72,15 @@ register_builtin! {
Ord => ord_expand,
PartialOrd => partial_ord_expand,
Eq => eq_expand,
PartialEq => partial_eq_expand
PartialEq => partial_eq_expand,
CoercePointee => coerce_pointee_expand
}
pub fn find_builtin_derive(ident: &name::Name) -> Option<BuiltinDeriveExpander> {
BuiltinDeriveExpander::find_by_name(ident)
}
#[derive(Clone)]
enum VariantShape {
Struct(Vec<tt::Ident>),
Tuple(usize),
@ -147,6 +154,7 @@ impl VariantShape {
}
}
#[derive(Clone)]
enum AdtShape {
Struct(VariantShape),
Enum { variants: Vec<(tt::Ident, VariantShape)>, default_variant: Option<usize> },
@ -197,30 +205,38 @@ impl AdtShape {
}
}
#[derive(Clone)]
struct BasicAdtInfo {
name: tt::Ident,
shape: AdtShape,
/// 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::TopSubtree, Option<tt::TopSubtree>, Option<tt::TopSubtree>)>,
param_types: Vec<AdtParam>,
where_clause: Vec<tt::TopSubtree>,
associated_types: Vec<tt::TopSubtree>,
}
#[derive(Clone)]
struct AdtParam {
name: tt::TopSubtree,
/// `None` if this is a type parameter.
const_ty: Option<tt::TopSubtree>,
bounds: Option<tt::TopSubtree>,
}
// FIXME: This whole thing needs a refactor. Each derive requires its special values, and the result is a mess.
fn parse_adt(tt: &tt::TopSubtree, call_site: Span) -> Result<BasicAdtInfo, ExpandError> {
let (parsed, tm) = &syntax_bridge::token_tree_to_syntax_node(
tt,
syntax_bridge::TopEntryPoint::MacroItems,
parser::Edition::CURRENT_FIXME,
);
let macro_items = ast::MacroItems::cast(parsed.syntax_node())
.ok_or_else(|| ExpandError::other(call_site, "invalid item definition"))?;
let item =
macro_items.items().next().ok_or_else(|| ExpandError::other(call_site, "no item found"))?;
let adt = &ast::Adt::cast(item.syntax().clone())
.ok_or_else(|| ExpandError::other(call_site, "expected struct, enum or union"))?;
let (name, generic_param_list, where_clause, shape) = match adt {
let (adt, tm) = to_adt_syntax(tt, call_site)?;
parse_adt_from_syntax(&adt, &tm, call_site)
}
fn parse_adt_from_syntax(
adt: &ast::Adt,
tm: &span::SpanMap<SyntaxContextId>,
call_site: Span,
) -> Result<BasicAdtInfo, ExpandError> {
let (name, generic_param_list, where_clause, shape) = match &adt {
ast::Adt::Struct(it) => (
it.name(),
it.generic_param_list(),
@ -291,7 +307,7 @@ fn parse_adt(tt: &tt::TopSubtree, call_site: Span) -> Result<BasicAdtInfo, Expan
}),
ast::TypeOrConstParam::Const(_) => None,
};
let ty = if let ast::TypeOrConstParam::Const(param) = param {
let const_ty = if let ast::TypeOrConstParam::Const(param) = param {
let ty = param
.ty()
.map(|ty| {
@ -309,7 +325,7 @@ fn parse_adt(tt: &tt::TopSubtree, call_site: Span) -> Result<BasicAdtInfo, Expan
} else {
None
};
(name, ty, bounds)
AdtParam { name, const_ty, bounds }
})
.collect();
@ -365,6 +381,24 @@ fn parse_adt(tt: &tt::TopSubtree, call_site: Span) -> Result<BasicAdtInfo, Expan
Ok(BasicAdtInfo { name: name_token, shape, param_types, where_clause, associated_types })
}
fn to_adt_syntax(
tt: &tt::TopSubtree,
call_site: Span,
) -> Result<(ast::Adt, span::SpanMap<SyntaxContextId>), ExpandError> {
let (parsed, tm) = syntax_bridge::token_tree_to_syntax_node(
tt,
syntax_bridge::TopEntryPoint::MacroItems,
parser::Edition::CURRENT_FIXME,
);
let macro_items = ast::MacroItems::cast(parsed.syntax_node())
.ok_or_else(|| ExpandError::other(call_site, "invalid item definition"))?;
let item =
macro_items.items().next().ok_or_else(|| ExpandError::other(call_site, "no item found"))?;
let adt = ast::Adt::cast(item.syntax().clone())
.ok_or_else(|| ExpandError::other(call_site, "expected struct, enum or union"))?;
Ok((adt, tm))
}
fn name_to_token(
call_site: Span,
token_map: &ExpansionSpanMap,
@ -426,38 +460,64 @@ fn expand_simple_derive(
)
}
};
ExpandResult::ok(expand_simple_derive_with_parsed(
invoc_span,
info,
trait_path,
make_trait_body,
true,
tt::TopSubtree::empty(tt::DelimSpan::from_single(invoc_span)),
))
}
fn expand_simple_derive_with_parsed(
invoc_span: Span,
info: BasicAdtInfo,
trait_path: tt::TopSubtree,
make_trait_body: impl FnOnce(&BasicAdtInfo) -> tt::TopSubtree,
constrain_to_trait: bool,
extra_impl_params: tt::TopSubtree,
) -> tt::TopSubtree {
let trait_body = make_trait_body(&info);
let mut where_block: Vec<_> =
info.where_clause.into_iter().map(|w| quote! {invoc_span => #w , }).collect();
let (params, args): (Vec<_>, Vec<_>) = info
.param_types
.into_iter()
.map(|(ident, param_ty, bound)| {
let ident_ = ident.clone();
if let Some(b) = bound {
let ident = ident.clone();
where_block.push(quote! {invoc_span => #ident : #b , });
.map(|param| {
let ident = param.name;
if let Some(b) = param.bounds {
let ident2 = ident.clone();
where_block.push(quote! {invoc_span => #ident2 : #b , });
}
if let Some(ty) = param_ty {
(quote! {invoc_span => const #ident : #ty , }, quote! {invoc_span => #ident_ , })
if let Some(ty) = param.const_ty {
let ident2 = ident.clone();
(quote! {invoc_span => const #ident : #ty , }, quote! {invoc_span => #ident2 , })
} else {
let bound = trait_path.clone();
(quote! {invoc_span => #ident : #bound , }, quote! {invoc_span => #ident_ , })
let ident2 = ident.clone();
let param = if constrain_to_trait {
quote! {invoc_span => #ident : #bound , }
} else {
quote! {invoc_span => #ident , }
};
(param, quote! {invoc_span => #ident2 , })
}
})
.unzip();
where_block.extend(info.associated_types.iter().map(|it| {
let it = it.clone();
let bound = trait_path.clone();
quote! {invoc_span => #it : #bound , }
}));
if constrain_to_trait {
where_block.extend(info.associated_types.iter().map(|it| {
let it = it.clone();
let bound = trait_path.clone();
quote! {invoc_span => #it : #bound , }
}));
}
let name = info.name;
let expanded = quote! {invoc_span =>
impl < ##params > #trait_path for #name < ##args > where ##where_block { #trait_body }
};
ExpandResult::ok(expanded)
quote! {invoc_span =>
impl < ##params #extra_impl_params > #trait_path for #name < ##args > where ##where_block { #trait_body }
}
}
fn copy_expand(span: Span, tt: &tt::TopSubtree) -> ExpandResult<tt::TopSubtree> {
@ -871,3 +931,493 @@ fn partial_ord_expand(span: Span, tt: &tt::TopSubtree) -> ExpandResult<tt::TopSu
}
})
}
fn coerce_pointee_expand(span: Span, tt: &tt::TopSubtree) -> ExpandResult<tt::TopSubtree> {
let (adt, _span_map) = match to_adt_syntax(tt, span) {
Ok(it) => it,
Err(err) => {
return ExpandResult::new(tt::TopSubtree::empty(tt::DelimSpan::from_single(span)), err);
}
};
let adt = adt.clone_for_update();
let ast::Adt::Struct(strukt) = &adt else {
return ExpandResult::new(
tt::TopSubtree::empty(tt::DelimSpan::from_single(span)),
ExpandError::other(span, "`CoercePointee` can only be derived on `struct`s"),
);
};
let has_at_least_one_field = strukt
.field_list()
.map(|it| match it {
ast::FieldList::RecordFieldList(it) => it.fields().next().is_some(),
ast::FieldList::TupleFieldList(it) => it.fields().next().is_some(),
})
.unwrap_or(false);
if !has_at_least_one_field {
return ExpandResult::new(
tt::TopSubtree::empty(tt::DelimSpan::from_single(span)),
ExpandError::other(
span,
"`CoercePointee` can only be derived on `struct`s with at least one field",
),
);
}
let is_repr_transparent = strukt.attrs().any(|attr| {
attr.as_simple_call().is_some_and(|(name, tt)| {
name == "repr"
&& tt.syntax().children_with_tokens().any(|it| {
it.into_token().is_some_and(|it| {
it.kind() == SyntaxKind::IDENT && it.text() == "transparent"
})
})
})
});
if !is_repr_transparent {
return ExpandResult::new(
tt::TopSubtree::empty(tt::DelimSpan::from_single(span)),
ExpandError::other(
span,
"`CoercePointee` can only be derived on `struct`s with `#[repr(transparent)]`",
),
);
}
let type_params = strukt
.generic_param_list()
.into_iter()
.flat_map(|generics| {
generics.generic_params().filter_map(|param| match param {
ast::GenericParam::TypeParam(param) => Some(param),
_ => None,
})
})
.collect_vec();
if type_params.is_empty() {
return ExpandResult::new(
tt::TopSubtree::empty(tt::DelimSpan::from_single(span)),
ExpandError::other(
span,
"`CoercePointee` can only be derived on `struct`s that are generic over at least one type",
),
);
}
let (pointee_param, pointee_param_idx) = if type_params.len() == 1 {
// Regardless of the only type param being designed as `#[pointee]` or not, we can just use it as such.
(type_params[0].clone(), 0)
} else {
let mut pointees = type_params.iter().cloned().enumerate().filter(|(_, param)| {
param.attrs().any(|attr| {
let is_pointee = attr.as_simple_atom().is_some_and(|name| name == "pointee");
if is_pointee {
// Remove the `#[pointee]` attribute so it won't be present in the generated
// impls (where we cannot resolve it).
ted::remove(attr.syntax());
}
is_pointee
})
});
match (pointees.next(), pointees.next()) {
(Some((pointee_idx, pointee)), None) => (pointee, pointee_idx),
(None, _) => {
return ExpandResult::new(
tt::TopSubtree::empty(tt::DelimSpan::from_single(span)),
ExpandError::other(
span,
"exactly one generic type parameter must be marked \
as `#[pointee]` to derive `CoercePointee` traits",
),
)
}
(Some(_), Some(_)) => {
return ExpandResult::new(
tt::TopSubtree::empty(tt::DelimSpan::from_single(span)),
ExpandError::other(
span,
"only one type parameter can be marked as `#[pointee]` \
when deriving `CoercePointee` traits",
),
)
}
}
};
let (Some(struct_name), Some(pointee_param_name)) = (strukt.name(), pointee_param.name())
else {
return ExpandResult::new(
tt::TopSubtree::empty(tt::DelimSpan::from_single(span)),
ExpandError::other(span, "invalid item"),
);
};
{
let mut pointee_has_maybe_sized_bound = false;
if let Some(bounds) = pointee_param.type_bound_list() {
pointee_has_maybe_sized_bound |= bounds.bounds().any(is_maybe_sized_bound);
}
if let Some(where_clause) = strukt.where_clause() {
pointee_has_maybe_sized_bound |= where_clause.predicates().any(|pred| {
let Some(ast::Type::PathType(ty)) = pred.ty() else { return false };
let is_not_pointee = ty.path().is_none_or(|path| {
let is_pointee = path
.as_single_name_ref()
.is_some_and(|name| name.text() == pointee_param_name.text());
!is_pointee
});
if is_not_pointee {
return false;
}
pred.type_bound_list()
.is_some_and(|bounds| bounds.bounds().any(is_maybe_sized_bound))
})
}
if !pointee_has_maybe_sized_bound {
return ExpandResult::new(
tt::TopSubtree::empty(tt::DelimSpan::from_single(span)),
ExpandError::other(
span,
format!("`derive(CoercePointee)` requires `{pointee_param_name}` to be marked `?Sized`"),
),
);
}
}
const ADDED_PARAM: &str = "__S";
let where_clause = strukt.get_or_create_where_clause();
{
let mut new_predicates = Vec::new();
// # Rewrite generic parameter bounds
// For each bound `U: ..` in `struct<U: ..>`, make a new bound with `__S` in place of `#[pointee]`
// Example:
// ```
// struct<
// U: Trait<T>,
// #[pointee] T: Trait<T> + ?Sized,
// V: Trait<T>> ...
// ```
// ... generates this `impl` generic parameters
// ```
// impl<
// U: Trait<T>,
// T: Trait<T> + ?Sized,
// V: Trait<T>
// >
// where
// U: Trait<__S>,
// __S: Trait<__S> + ?Sized,
// V: Trait<__S> ...
// ```
for param in &type_params {
let Some(param_name) = param.name() else { continue };
if let Some(bounds) = param.type_bound_list() {
// If the target type is the pointee, duplicate the bound as whole.
// Otherwise, duplicate only bounds that mention the pointee.
let is_pointee = param_name.text() == pointee_param_name.text();
let new_bounds = bounds
.bounds()
.map(|bound| bound.clone_subtree().clone_for_update())
.filter(|bound| {
bound.ty().is_some_and(|ty| {
substitute_type_in_bound(ty, &pointee_param_name.text(), ADDED_PARAM)
|| is_pointee
})
});
let new_bounds_target = if is_pointee {
make::name_ref(ADDED_PARAM)
} else {
make::name_ref(&param_name.text())
};
new_predicates.push(
make::where_pred(
make::ty_path(make::path_from_segments(
[make::path_segment(new_bounds_target)],
false,
)),
new_bounds,
)
.clone_for_update(),
);
}
}
// # Rewrite `where` clauses
//
// Move on to `where` clauses.
// Example:
// ```
// struct MyPointer<#[pointee] T, ..>
// where
// U: Trait<V> + Trait<T>,
// Companion<T>: Trait<T>,
// T: Trait<T> + ?Sized,
// { .. }
// ```
// ... will have a impl prelude like so
// ```
// impl<..> ..
// where
// U: Trait<V> + Trait<T>,
// U: Trait<__S>,
// Companion<T>: Trait<T>,
// Companion<__S>: Trait<__S>,
// T: Trait<T> + ?Sized,
// __S: Trait<__S> + ?Sized,
// ```
//
// We should also write a few new `where` bounds from `#[pointee] T` to `__S`
// as well as any bound that indirectly involves the `#[pointee] T` type.
for predicate in where_clause.predicates() {
let predicate = predicate.clone_subtree().clone_for_update();
let Some(pred_target) = predicate.ty() else { continue };
// If the target type references the pointee, duplicate the bound as whole.
// Otherwise, duplicate only bounds that mention the pointee.
if substitute_type_in_bound(
pred_target.clone(),
&pointee_param_name.text(),
ADDED_PARAM,
) {
if let Some(bounds) = predicate.type_bound_list() {
for bound in bounds.bounds() {
if let Some(ty) = bound.ty() {
substitute_type_in_bound(ty, &pointee_param_name.text(), ADDED_PARAM);
}
}
}
new_predicates.push(predicate);
} else if let Some(bounds) = predicate.type_bound_list() {
let new_bounds = bounds
.bounds()
.map(|bound| bound.clone_subtree().clone_for_update())
.filter(|bound| {
bound.ty().is_some_and(|ty| {
substitute_type_in_bound(ty, &pointee_param_name.text(), ADDED_PARAM)
})
});
new_predicates.push(make::where_pred(pred_target, new_bounds).clone_for_update());
}
}
for new_predicate in new_predicates {
where_clause.add_predicate(new_predicate);
}
}
{
// # Add `Unsize<__S>` bound to `#[pointee]` at the generic parameter location
//
// Find the `#[pointee]` parameter and add an `Unsize<__S>` bound to it.
where_clause.add_predicate(
make::where_pred(
make::ty_path(make::path_from_segments(
[make::path_segment(make::name_ref(&pointee_param_name.text()))],
false,
)),
[make::type_bound(make::ty_path(make::path_from_segments(
[
make::path_segment(make::name_ref("core")),
make::path_segment(make::name_ref("marker")),
make::generic_ty_path_segment(
make::name_ref("Unsize"),
[make::type_arg(make::ty_path(make::path_from_segments(
[make::path_segment(make::name_ref(ADDED_PARAM))],
false,
)))
.into()],
),
],
true,
)))],
)
.clone_for_update(),
);
}
let self_for_traits = {
// Replace the `#[pointee]` with `__S`.
let mut type_param_idx = 0;
let self_params_for_traits = strukt
.generic_param_list()
.into_iter()
.flat_map(|params| params.generic_params())
.filter_map(|param| {
Some(match param {
ast::GenericParam::ConstParam(param) => {
ast::GenericArg::ConstArg(make::expr_const_value(&param.name()?.text()))
}
ast::GenericParam::LifetimeParam(param) => {
make::lifetime_arg(param.lifetime()?).into()
}
ast::GenericParam::TypeParam(param) => {
let name = if pointee_param_idx == type_param_idx {
make::name_ref(ADDED_PARAM)
} else {
make::name_ref(&param.name()?.text())
};
type_param_idx += 1;
make::type_arg(make::ty_path(make::path_from_segments(
[make::path_segment(name)],
false,
)))
.into()
}
})
});
let self_for_traits = make::path_from_segments(
[make::generic_ty_path_segment(
make::name_ref(&struct_name.text()),
self_params_for_traits,
)],
false,
)
.clone_for_update();
self_for_traits
};
let mut span_map = span::SpanMap::empty();
// One span for them all.
span_map.push(adt.syntax().text_range().end(), span);
let self_for_traits = syntax_bridge::syntax_node_to_token_tree(
self_for_traits.syntax(),
&span_map,
span,
DocCommentDesugarMode::ProcMacro,
);
let info = match parse_adt_from_syntax(&adt, &span_map, span) {
Ok(it) => it,
Err(err) => {
return ExpandResult::new(tt::TopSubtree::empty(tt::DelimSpan::from_single(span)), err)
}
};
let self_for_traits2 = self_for_traits.clone();
let krate = dollar_crate(span);
let krate2 = krate.clone();
let dispatch_from_dyn = expand_simple_derive_with_parsed(
span,
info.clone(),
quote! {span => #krate2::ops::DispatchFromDyn<#self_for_traits2> },
|_adt| quote! {span => },
false,
quote! {span => __S },
);
let coerce_unsized = expand_simple_derive_with_parsed(
span,
info,
quote! {span => #krate::ops::CoerceUnsized<#self_for_traits> },
|_adt| quote! {span => },
false,
quote! {span => __S },
);
return ExpandResult::ok(quote! {span => #dispatch_from_dyn #coerce_unsized });
fn is_maybe_sized_bound(bound: ast::TypeBound) -> bool {
if bound.question_mark_token().is_none() {
return false;
}
let Some(ast::Type::PathType(ty)) = bound.ty() else {
return false;
};
let Some(path) = ty.path() else {
return false;
};
return segments_eq(&path, &["Sized"])
|| segments_eq(&path, &["core", "marker", "Sized"])
|| segments_eq(&path, &["std", "marker", "Sized"]);
fn segments_eq(path: &ast::Path, expected: &[&str]) -> bool {
path.segments().zip_longest(expected.iter().copied()).all(|value| {
value.both().is_some_and(|(segment, expected)| {
segment.name_ref().is_some_and(|name| name.text() == expected)
})
})
}
}
/// Returns true if any substitution was performed.
fn substitute_type_in_bound(ty: ast::Type, param_name: &str, replacement: &str) -> bool {
return match ty {
ast::Type::ArrayType(ty) => {
ty.ty().is_some_and(|ty| substitute_type_in_bound(ty, param_name, replacement))
}
ast::Type::DynTraitType(ty) => go_bounds(ty.type_bound_list(), param_name, replacement),
ast::Type::FnPtrType(ty) => any_long(
ty.param_list()
.into_iter()
.flat_map(|params| params.params().filter_map(|param| param.ty()))
.chain(ty.ret_type().and_then(|it| it.ty())),
|ty| substitute_type_in_bound(ty, param_name, replacement),
),
ast::Type::ForType(ty) => {
ty.ty().is_some_and(|ty| substitute_type_in_bound(ty, param_name, replacement))
}
ast::Type::ImplTraitType(ty) => {
go_bounds(ty.type_bound_list(), param_name, replacement)
}
ast::Type::ParenType(ty) => {
ty.ty().is_some_and(|ty| substitute_type_in_bound(ty, param_name, replacement))
}
ast::Type::PathType(ty) => ty.path().is_some_and(|path| {
if path.as_single_name_ref().is_some_and(|name| name.text() == param_name) {
ted::replace(
path.syntax(),
make::path_from_segments(
[make::path_segment(make::name_ref(replacement))],
false,
)
.clone_for_update()
.syntax(),
);
return true;
}
any_long(
path.segments()
.filter_map(|segment| segment.generic_arg_list())
.flat_map(|it| it.generic_args())
.filter_map(|generic_arg| match generic_arg {
ast::GenericArg::TypeArg(ty) => ty.ty(),
_ => None,
}),
|ty| substitute_type_in_bound(ty, param_name, replacement),
)
}),
ast::Type::PtrType(ty) => {
ty.ty().is_some_and(|ty| substitute_type_in_bound(ty, param_name, replacement))
}
ast::Type::RefType(ty) => {
ty.ty().is_some_and(|ty| substitute_type_in_bound(ty, param_name, replacement))
}
ast::Type::SliceType(ty) => {
ty.ty().is_some_and(|ty| substitute_type_in_bound(ty, param_name, replacement))
}
ast::Type::TupleType(ty) => {
any_long(ty.fields(), |ty| substitute_type_in_bound(ty, param_name, replacement))
}
ast::Type::InferType(_) | ast::Type::MacroType(_) | ast::Type::NeverType(_) => false,
};
fn go_bounds(
bounds: Option<ast::TypeBoundList>,
param_name: &str,
replacement: &str,
) -> bool {
bounds.is_some_and(|bounds| {
any_long(bounds.bounds(), |bound| {
bound
.ty()
.is_some_and(|ty| substitute_type_in_bound(ty, param_name, replacement))
})
})
}
/// Like [`Iterator::any()`], but not short-circuiting.
fn any_long<I: Iterator, F: FnMut(I::Item) -> bool>(iter: I, mut f: F) -> bool {
let mut result = false;
iter.for_each(|item| result |= f(item));
result
}
}
}