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Support C++ import for anonymous struct and union members. (#5855)

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This commit is contained in:
Richard Smith
2025-07-28 20:26:24 +00:00
committed by GitHub
parent 5dc299f58b
commit 0d74162e2a
3 changed files with 235 additions and 8 deletions
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toolchain/check/import_cpp.cpp
+44 -8
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@@ -543,19 +543,44 @@ static auto ImportClassObjectRepr(Context& context,
// TODO: Import bases.
// Import fields.
for (auto* field : clang_def->fields()) {
for (auto* decl : clang_def->decls()) {
auto* field = clang::dyn_cast<clang::FieldDecl>(decl);
// Track the chain of fields from the class to this field. This chain is
// only one element long unless the field is a member of an anonymous struct
// or union.
clang::NamedDecl* single_field_chain[1] = {field};
llvm::ArrayRef<clang::NamedDecl*> chain = single_field_chain;
// If this isn't a field, it might be an indirect field in an anonymous
// struct or union.
if (!field) {
auto* indirect_field = clang::dyn_cast<clang::IndirectFieldDecl>(decl);
if (!indirect_field) {
continue;
}
chain = indirect_field->chain();
field = indirect_field->getAnonField();
}
if (field->isBitField()) {
// TODO: Add a representation for named bitfield members.
continue;
}
if (field->isAnonymousStructOrUnion()) {
// TODO: Visit IndirectFieldDecls and add them to the layout.
// Fields within an anonymous structure or union will be added via their
// IndirectFieldDecls.
continue;
}
auto field_name_id = AddIdentifierName(context, field->getName());
auto [field_type_inst_id, field_type_id] =
MapType(context, import_ir_inst_id, field->getType());
if (!field_type_inst_id.has_value()) {
// TODO: For now, just skip over fields whose types we can't map.
continue;
}
// Create a field now, as we know the index to use.
// TODO: Consider doing this lazily instead.
@@ -568,12 +593,23 @@ static auto ImportClassObjectRepr(Context& context,
.name_id = field_name_id,
.index = SemIR::ElementIndex(fields.size())}));
context.sem_ir().clang_decls().Add(
{.decl = field->getCanonicalDecl(), .inst_id = field_decl_id});
{.decl = decl->getCanonicalDecl(), .inst_id = field_decl_id});
layout.push_back(context.ast_context()
.toCharUnitsFromBits(clang_layout.getFieldOffset(
field->getFieldIndex()))
.getQuantity());
// Compute the offset to the field that appears directly in the class.
uint64_t offset = clang_layout.getFieldOffset(
clang::cast<clang::FieldDecl>(chain.front())->getFieldIndex());
// If this is an indirect field, walk the path and accumulate the offset to
// the named field.
for (auto* inner_decl : chain.drop_front()) {
auto* inner_field = clang::cast<clang::FieldDecl>(inner_decl);
const auto& inner_layout =
context.ast_context().getASTRecordLayout(inner_field->getParent());
offset += inner_layout.getFieldOffset(inner_field->getFieldIndex());
}
layout.push_back(
context.ast_context().toCharUnitsFromBits(offset).getQuantity());
fields.push_back(
{.name_id = field_name_id, .type_inst_id = field_type_inst_id});
}
@@ -1228,7 +1264,7 @@ static auto ImportDeclAfterDependencies(Context& context, SemIR::LocId loc_id,
}
return type_inst_id;
}
if (clang::isa<clang::FieldDecl>(clang_decl)) {
if (clang::isa<clang::FieldDecl, clang::IndirectFieldDecl>(clang_decl)) {
// Usable fields get imported as a side effect of importing the class.
if (SemIR::InstId existing_inst_id =
LookupClangDeclInstId(context, clang_decl);