Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Simplify universal impl trait lowering #97598

Merged
merged 14 commits into from
Jun 3, 2022
Merged

Simplify universal impl trait lowering #97598

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
14 commits
Select commit Hold shift + click to select a range
3d6eae8
Move defs and bounds from Universal to LoweringContext
spastorino May 31, 2022
1a71103
Take and restore fields in with_hir_id_owner calls
spastorino May 31, 2022
190b4a7
Add itctx: ImplTraitContext arg to add_implicit_generics
spastorino May 31, 2022
e080298
Replace calls to lower_generics with calls to add_implicit_generics
spastorino May 31, 2022
d5ab8b2
Rename add_implicit_generics to lower_generics
spastorino May 31, 2022
bd3a097
Move lower_generics definition to item.rs
spastorino May 31, 2022
208ffbb
derive Copy, Clone, PartialEq, Eq for ImplTraitContext
spastorino May 31, 2022
d327db9
Remove ImplTraitContext::reborrow
spastorino May 31, 2022
2ade55d
Inline lower_generics_mut and remove GenericsCtor
spastorino May 31, 2022
15f2b11
Fix lower_generics rustdocs
spastorino May 31, 2022
b3bc438
Add debug_assert comment
spastorino Jun 1, 2022
2de2520
Split extend + inner chain into to extend calls
spastorino Jun 1, 2022
67deaf9
instrument lower_fn_decl
spastorino Jun 1, 2022
15a82d6
Always assert that impl_trait_def|bounds are empty at start
spastorino Jun 1, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
272 changes: 137 additions & 135 deletions compiler/rustc_ast_lowering/src/item.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,8 @@ impl<'a, 'hir> ItemLowerer<'a, 'hir> {
task_context: None,
current_item: None,
captured_lifetimes: None,
impl_trait_defs: Vec::new(),
impl_trait_bounds: Vec::new(),
allow_try_trait: Some([sym::try_trait_v2, sym::yeet_desugar_details][..].into()),
allow_gen_future: Some([sym::gen_future][..].into()),
allow_into_future: Some([sym::into_future][..].into()),
Expand Down Expand Up @@ -264,16 +266,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
let body_id =
this.lower_maybe_async_body(span, &decl, asyncness, body.as_deref());

let (generics, decl) =
this.add_implicit_generics(generics, id, |this, idty, idpb| {
let ret_id = asyncness.opt_return_id();
this.lower_fn_decl(
&decl,
Some((id, idty, idpb)),
FnDeclKind::Fn,
ret_id,
)
});
let itctx = ImplTraitContext::Universal(this.current_hir_id_owner);
let (generics, decl) = this.lower_generics(generics, id, itctx, |this| {
let ret_id = asyncness.opt_return_id();
this.lower_fn_decl(&decl, Some(id), FnDeclKind::Fn, ret_id)
});
let sig = hir::FnSig {
decl,
header: this.lower_fn_header(header),
Expand Down Expand Up @@ -311,57 +308,59 @@ impl<'hir> LoweringContext<'_, 'hir> {
//
// type Foo = Foo1
// opaque type Foo1: Trait
let ty = self.lower_ty(ty, ImplTraitContext::TypeAliasesOpaqueTy);
let mut generics = generics.clone();
add_ty_alias_where_clause(&mut generics, where_clauses, true);
let generics = self.lower_generics(
let (generics, ty) = self.lower_generics(
&generics,
id,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
|this| this.lower_ty(ty, ImplTraitContext::TypeAliasesOpaqueTy),
);
hir::ItemKind::TyAlias(ty, generics)
}
ItemKind::TyAlias(box TyAlias {
ref generics, ref where_clauses, ty: None, ..
}) => {
let ty = self.arena.alloc(self.ty(span, hir::TyKind::Err));
let mut generics = generics.clone();
add_ty_alias_where_clause(&mut generics, *where_clauses, true);
let generics = self.lower_generics(
let (generics, ty) = self.lower_generics(
&generics,
id,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
|this| this.arena.alloc(this.ty(span, hir::TyKind::Err)),
);
hir::ItemKind::TyAlias(ty, generics)
}
ItemKind::Enum(ref enum_definition, ref generics) => hir::ItemKind::Enum(
hir::EnumDef {
variants: self.arena.alloc_from_iter(
enum_definition.variants.iter().map(|x| self.lower_variant(x)),
),
},
self.lower_generics(
ItemKind::Enum(ref enum_definition, ref generics) => {
let (generics, variants) = self.lower_generics(
generics,
id,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
),
),
|this| {
this.arena.alloc_from_iter(
enum_definition.variants.iter().map(|x| this.lower_variant(x)),
)
},
);
hir::ItemKind::Enum(hir::EnumDef { variants }, generics)
}
ItemKind::Struct(ref struct_def, ref generics) => {
let struct_def = self.lower_variant_data(hir_id, struct_def);
hir::ItemKind::Struct(
struct_def,
self.lower_generics(
generics,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
),
)
let (generics, struct_def) = self.lower_generics(
generics,
id,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
|this| this.lower_variant_data(hir_id, struct_def),
);
hir::ItemKind::Struct(struct_def, generics)
}
ItemKind::Union(ref vdata, ref generics) => {
let vdata = self.lower_variant_data(hir_id, vdata);
hir::ItemKind::Union(
vdata,
self.lower_generics(
generics,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
),
)
let (generics, vdata) = self.lower_generics(
generics,
id,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
|this| this.lower_variant_data(hir_id, vdata),
);
hir::ItemKind::Union(vdata, generics)
}
ItemKind::Impl(box Impl {
unsafety,
Expand All @@ -386,8 +385,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
// method, it will not be considered an in-band
// lifetime to be added, but rather a reference to a
// parent lifetime.
let itctx = ImplTraitContext::Universal(self.current_hir_id_owner);
let (generics, (trait_ref, lowered_ty)) =
self.add_implicit_generics(ast_generics, id, |this, _, _| {
self.lower_generics(ast_generics, id, itctx, |this| {
let trait_ref = trait_ref.as_ref().map(|trait_ref| {
this.lower_trait_ref(
trait_ref,
Expand Down Expand Up @@ -432,34 +432,38 @@ impl<'hir> LoweringContext<'_, 'hir> {
ref bounds,
ref items,
}) => {
let bounds = self.lower_param_bounds(
bounds,
ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
let (generics, (unsafety, items, bounds)) = self.lower_generics(
generics,
id,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
|this| {
let bounds = this.lower_param_bounds(
bounds,
ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
);
let items = this.arena.alloc_from_iter(
items.iter().map(|item| this.lower_trait_item_ref(item)),
);
let unsafety = this.lower_unsafety(unsafety);
(unsafety, items, bounds)
},
);
let items = self
.arena
.alloc_from_iter(items.iter().map(|item| self.lower_trait_item_ref(item)));
hir::ItemKind::Trait(
is_auto,
self.lower_unsafety(unsafety),
self.lower_generics(
generics,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
),
bounds,
items,
)
hir::ItemKind::Trait(is_auto, unsafety, generics, bounds, items)
}
ItemKind::TraitAlias(ref generics, ref bounds) => hir::ItemKind::TraitAlias(
self.lower_generics(
ItemKind::TraitAlias(ref generics, ref bounds) => {
let (generics, bounds) = self.lower_generics(
generics,
id,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
),
self.lower_param_bounds(
bounds,
ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
),
),
|this| {
this.lower_param_bounds(
bounds,
ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
)
},
);
hir::ItemKind::TraitAlias(generics, bounds)
}
ItemKind::MacroDef(MacroDef { ref body, macro_rules }) => {
let body = P(self.lower_mac_args(body));
let macro_kind = self.resolver.decl_macro_kind(self.resolver.local_def_id(id));
Expand Down Expand Up @@ -651,8 +655,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
kind: match i.kind {
ForeignItemKind::Fn(box Fn { ref sig, ref generics, .. }) => {
let fdec = &sig.decl;
let itctx = ImplTraitContext::Universal(self.current_hir_id_owner);
let (generics, (fn_dec, fn_args)) =
self.add_implicit_generics(generics, i.id, |this, _, _| {
self.lower_generics(generics, i.id, itctx, |this| {
(
// Disallow `impl Trait` in foreign items.
this.lower_fn_decl(fdec, None, FnDeclKind::ExternFn, None),
Expand Down Expand Up @@ -789,24 +794,25 @@ impl<'hir> LoweringContext<'_, 'hir> {
ref ty,
..
}) => {
let ty = ty.as_ref().map(|x| {
self.lower_ty(x, ImplTraitContext::Disallowed(ImplTraitPosition::Type))
});
let mut generics = generics.clone();
add_ty_alias_where_clause(&mut generics, where_clauses, false);
let generics = self.lower_generics(
self.lower_generics(
&generics,
i.id,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
);
let kind = hir::TraitItemKind::Type(
self.lower_param_bounds(
bounds,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
),
ty,
);

(generics, kind)
|this| {
let ty = ty.as_ref().map(|x| {
this.lower_ty(x, ImplTraitContext::Disallowed(ImplTraitPosition::Type))
});
hir::TraitItemKind::Type(
this.lower_param_bounds(
bounds,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
),
ty,
)
},
)
}
AssocItemKind::MacCall(..) => panic!("macro item shouldn't exist at this point"),
};
Expand Down Expand Up @@ -876,21 +882,21 @@ impl<'hir> LoweringContext<'_, 'hir> {
AssocItemKind::TyAlias(box TyAlias { generics, where_clauses, ty, .. }) => {
let mut generics = generics.clone();
add_ty_alias_where_clause(&mut generics, *where_clauses, false);
let generics = self.lower_generics(
self.lower_generics(
&generics,
i.id,
ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
);
let kind = match ty {
None => {
let ty = self.arena.alloc(self.ty(i.span, hir::TyKind::Err));
hir::ImplItemKind::TyAlias(ty)
}
Some(ty) => {
let ty = self.lower_ty(ty, ImplTraitContext::TypeAliasesOpaqueTy);
hir::ImplItemKind::TyAlias(ty)
}
};
(generics, kind)
|this| match ty {
None => {
let ty = this.arena.alloc(this.ty(i.span, hir::TyKind::Err));
hir::ImplItemKind::TyAlias(ty)
}
Some(ty) => {
let ty = this.lower_ty(ty, ImplTraitContext::TypeAliasesOpaqueTy);
hir::ImplItemKind::TyAlias(ty)
}
},
)
}
AssocItemKind::MacCall(..) => panic!("`TyMac` should have been expanded by now"),
};
Expand Down Expand Up @@ -1231,8 +1237,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
is_async: Option<NodeId>,
) -> (&'hir hir::Generics<'hir>, hir::FnSig<'hir>) {
let header = self.lower_fn_header(sig.header);
let (generics, decl) = self.add_implicit_generics(generics, id, |this, idty, idpb| {
this.lower_fn_decl(&sig.decl, Some((id, idty, idpb)), kind, is_async)
let itctx = ImplTraitContext::Universal(self.current_hir_id_owner);
let (generics, decl) = self.lower_generics(generics, id, itctx, |this| {
this.lower_fn_decl(&sig.decl, Some(id), kind, is_async)
});
(generics, hir::FnSig { header, decl, span: self.lower_span(sig.span) })
}
Expand Down Expand Up @@ -1289,11 +1296,18 @@ impl<'hir> LoweringContext<'_, 'hir> {
}
}

pub(super) fn lower_generics_mut(
/// Return the pair of the lowered `generics` as `hir::Generics` and the evaluation of `f` with
/// the carried impl trait definitions and bounds.
fn lower_generics<T>(
&mut self,
generics: &Generics,
mut itctx: ImplTraitContext<'_, 'hir>,
) -> GenericsCtor<'hir> {
parent_node_id: NodeId,
itctx: ImplTraitContext,
f: impl FnOnce(&mut Self) -> T,
) -> (&'hir hir::Generics<'hir>, T) {
debug_assert!(self.impl_trait_defs.is_empty());
debug_assert!(self.impl_trait_bounds.is_empty());

// Error if `?Trait` bounds in where clauses don't refer directly to type parameters.
// Note: we used to clone these bounds directly onto the type parameter (and avoid lowering
// these into hir when we lower thee where clauses), but this makes it quite difficult to
Expand Down Expand Up @@ -1341,9 +1355,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
}
}

let mut predicates = SmallVec::new();
let mut predicates: SmallVec<[hir::WherePredicate<'hir>; 4]> = SmallVec::new();
predicates.extend(generics.params.iter().filter_map(|param| {
let bounds = self.lower_param_bounds(&param.bounds, itctx.reborrow());
let bounds = self.lower_param_bounds(&param.bounds, itctx);
self.lower_generic_bound_predicate(
param.ident,
param.id,
Expand All @@ -1360,22 +1374,31 @@ impl<'hir> LoweringContext<'_, 'hir> {
.map(|predicate| self.lower_where_predicate(predicate)),
);

GenericsCtor {
params: self.lower_generic_params_mut(&generics.params).collect(),
predicates,
has_where_clause: !generics.where_clause.predicates.is_empty(),
where_clause_span: self.lower_span(generics.where_clause.span),
span: self.lower_span(generics.span),
}
}
let mut params: Vec<_> = self.lower_generic_params_mut(&generics.params).collect();
let has_where_clause = !generics.where_clause.predicates.is_empty();
let where_clause_span = self.lower_span(generics.where_clause.span);
let span = self.lower_span(generics.span);
let res = f(self);

pub(super) fn lower_generics(
&mut self,
generics: &Generics,
itctx: ImplTraitContext<'_, 'hir>,
) -> &'hir hir::Generics<'hir> {
let generics_ctor = self.lower_generics_mut(generics, itctx);
generics_ctor.into_generics(self.arena)
let extra_lifetimes = self.resolver.take_extra_lifetime_params(parent_node_id);
let impl_trait_defs = std::mem::take(&mut self.impl_trait_defs);
params.extend(extra_lifetimes.into_iter().filter_map(|(ident, node_id, res)| {
self.lifetime_res_to_generic_param(ident, node_id, res)
}));
params.extend(impl_trait_defs.into_iter());

let impl_trait_bounds = std::mem::take(&mut self.impl_trait_bounds);
predicates.extend(impl_trait_bounds.into_iter());

let lowered_generics = self.arena.alloc(hir::Generics {
params: self.arena.alloc_from_iter(params),
predicates: self.arena.alloc_from_iter(predicates),
has_where_clause,
where_clause_span,
span,
});

(lowered_generics, res)
}

pub(super) fn lower_generic_bound_predicate(
Expand Down Expand Up @@ -1491,24 +1514,3 @@ impl<'hir> LoweringContext<'_, 'hir> {
}
}
}

/// Helper struct for delayed construction of Generics.
pub(super) struct GenericsCtor<'hir> {
pub(super) params: SmallVec<[hir::GenericParam<'hir>; 4]>,
pub(super) predicates: SmallVec<[hir::WherePredicate<'hir>; 4]>,
has_where_clause: bool,
where_clause_span: Span,
span: Span,
}

impl<'hir> GenericsCtor<'hir> {
pub(super) fn into_generics(self, arena: &'hir Arena<'hir>) -> &'hir hir::Generics<'hir> {
arena.alloc(hir::Generics {
params: arena.alloc_from_iter(self.params),
predicates: arena.alloc_from_iter(self.predicates),
has_where_clause: self.has_where_clause,
where_clause_span: self.where_clause_span,
span: self.span,
})
}
}
Loading