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rustc_metadata: Add struct and variant constructors to module children at encoding time #103524

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Oct 28, 2022
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rustc_metadata: Add struct and variant constructors to module children at encoding time #103524

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79 changes: 35 additions & 44 deletions compiler/rustc_metadata/src/rmeta/decoder.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -773,7 +773,15 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
}

fn opt_item_name(self, item_index: DefIndex) -> Option<Symbol> {
self.def_key(item_index).disambiguated_data.data.get_opt_name()
let def_key = self.def_key(item_index);
def_key.disambiguated_data.data.get_opt_name().or_else(|| {
if def_key.disambiguated_data.data == DefPathData::Ctor {
let parent_index = def_key.parent.expect("no parent for a constructor");
self.def_key(parent_index).disambiguated_data.data.get_opt_name()
} else {
None
}
})
}

fn item_name(self, item_index: DefIndex) -> Symbol {
Expand Down Expand Up @@ -905,7 +913,13 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
.get(self, item_id)
.unwrap_or_else(LazyArray::empty)
.decode(self)
.map(|index| self.get_variant(&self.def_kind(index), index, did))
.filter_map(|index| {
let kind = self.def_kind(index);
match kind {
DefKind::Ctor(..) => None,
_ => Some(self.get_variant(&kind, index, did)),
}
})
.collect()
} else {
std::iter::once(self.get_variant(&kind, item_id, did)).collect()
Expand Down Expand Up @@ -1029,50 +1043,27 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {

callback(ModChild { ident, res, vis, span, macro_rules });

// For non-re-export structs and variants add their constructors to children.
// Re-export lists automatically contain constructors when necessary.
match kind {
DefKind::Struct => {
if let Some((ctor_def_id, ctor_kind)) =
self.get_ctor_def_id_and_kind(child_index)
{
let ctor_res =
Res::Def(DefKind::Ctor(CtorOf::Struct, ctor_kind), ctor_def_id);
let vis = self.get_visibility(ctor_def_id.index);
callback(ModChild {
ident,
res: ctor_res,
vis,
span,
macro_rules: false,
});
}
}
DefKind::Variant => {
// Braced variants, unlike structs, generate unusable names in
// value namespace, they are reserved for possible future use.
// It's ok to use the variant's id as a ctor id since an
// error will be reported on any use of such resolution anyway.
let (ctor_def_id, ctor_kind) = self
.get_ctor_def_id_and_kind(child_index)
.unwrap_or((def_id, CtorKind::Fictive));
let ctor_res =
Res::Def(DefKind::Ctor(CtorOf::Variant, ctor_kind), ctor_def_id);
let mut vis = self.get_visibility(ctor_def_id.index);
if ctor_def_id == def_id && vis.is_public() {
// For non-exhaustive variants lower the constructor visibility to
// within the crate. We only need this for fictive constructors,
// for other constructors correct visibilities
// were already encoded in metadata.
let mut attrs = self.get_item_attrs(def_id.index, sess);
if attrs.any(|item| item.has_name(sym::non_exhaustive)) {
let crate_def_id = self.local_def_id(CRATE_DEF_INDEX);
vis = ty::Visibility::Restricted(crate_def_id);
}
// For non-reexport variants add their fictive constructors to children.
// Braced variants, unlike structs, generate unusable names in value namespace,
// they are reserved for possible future use. It's ok to use the variant's id as
// a ctor id since an error will be reported on any use of such resolution anyway.
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Could we get rid of this special case by giving a dedicated NodeId and LocalDefId to the ctor of struct variants that is different from the struct variant itself?

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@petrochenkov petrochenkov Oct 25, 2022 •
edited
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I have something better in the pipeline - removing all this stuff entirely petrochenkov@be00274.
UPD: PR submitted in #103578.

// Reexport lists automatically contain such constructors when necessary.
if kind == DefKind::Variant && self.get_ctor_def_id_and_kind(child_index).is_none()
{
let ctor_res =
Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fictive), def_id);
let mut vis = vis;
if vis.is_public() {
// For non-exhaustive variants lower the constructor visibility to
// within the crate. We only need this for fictive constructors,
// for other constructors correct visibilities
// were already encoded in metadata.
let mut attrs = self.get_item_attrs(def_id.index, sess);
if attrs.any(|item| item.has_name(sym::non_exhaustive)) {
vis = ty::Visibility::Restricted(self.local_def_id(CRATE_DEF_INDEX));
}
callback(ModChild { ident, res: ctor_res, vis, span, macro_rules: false });
}
_ => {}
callback(ModChild { ident, res: ctor_res, vis, span, macro_rules: false });
}
}
}
Expand Down
24 changes: 18 additions & 6 deletions compiler/rustc_metadata/src/rmeta/encoder.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1335,6 +1335,13 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
// Only encode named non-reexport children, reexports are encoded
// separately and unnamed items are not used by name resolution.
hir::ItemKind::ExternCrate(..) => continue,
hir::ItemKind::Struct(ref vdata, _) => {
yield item_id.def_id.def_id.local_def_index;
// Encode constructors which take a separate slot in value namespace.
if let Some(ctor_hir_id) = vdata.ctor_hir_id() {
yield tcx.hir().local_def_id(ctor_hir_id).local_def_index;
}
}
_ if tcx.def_key(item_id.def_id.to_def_id()).get_opt_name().is_some() => {
yield item_id.def_id.def_id.local_def_index;
}
Expand Down Expand Up @@ -1646,12 +1653,17 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
};
// FIXME(eddyb) there should be a nicer way to do this.
match item.kind {
hir::ItemKind::Enum(..) => record_array!(self.tables.children[def_id] <-
self.tcx.adt_def(def_id).variants().iter().map(|v| {
assert!(v.def_id.is_local());
v.def_id.index
})
),
hir::ItemKind::Enum(..) => {
record_array!(self.tables.children[def_id] <- iter::from_generator(||
for variant in tcx.adt_def(def_id).variants() {
yield variant.def_id.index;
// Encode constructors which take a separate slot in value namespace.
if let Some(ctor_def_id) = variant.ctor_def_id {
yield ctor_def_id.index;
}
}
))
}
hir::ItemKind::Struct(..) | hir::ItemKind::Union(..) => {
record_array!(self.tables.children[def_id] <-
self.tcx.adt_def(def_id).non_enum_variant().fields.iter().map(|f| {
Expand Down