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Rework name lookup to handle non-lexical scoping. (#3354)

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When declaring a name such as `fn Ns.Class.F() { ... }`, enter the
scopes of `Ns` and `Ns.Class` as we form the name, and remain in those
non-lexical scopes until the end of the declaration.

When performing an unqualified lookup, look in any enclosing non-lexical
scopes in addition to looking into the lexical name table.

We now track a scope index with each lookup result in the lexical name
lookup table. This is used to determine whether a lexical or non-lexcial
result is the innermost result and whether a declared name is in the
same scope as some previous introduction of that name or in a nested
scope. For now, this could just be the index into the scope_stack, but
the intent is to also use this to detect names being declared after they
are first looked up, which requires the indexes to outlive their scopes,
so we use a persistent numbering of all scopes instead. The persistent
numbering also permits more invariant checking.
This commit is contained in:
Richard Smith
2023-11-06 19:48:41 +00:00
committed by GitHub
parent a4c0febc0f
commit 3bee8932a9
18 changed files with 766 additions and 150 deletions
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toolchain/check/declaration_name_stack.cpp
+34 -17
View File
@@ -9,7 +9,8 @@
namespace Carbon::Check {
auto DeclarationNameStack::MakeEmptyNameContext() -> NameContext {
return NameContext{.target_scope_id = context_->current_scope_id()};
return NameContext{.enclosing_scope = context_->current_scope_index(),
.target_scope_id = context_->current_scope_id()};
}
auto DeclarationNameStack::MakeUnqualifiedName(Parse::Node parse_node,
@@ -20,11 +21,14 @@ auto DeclarationNameStack::MakeUnqualifiedName(Parse::Node parse_node,
return context;
}
auto DeclarationNameStack::Push() -> void {
auto DeclarationNameStack::PushScopeAndStartName() -> void {
declaration_name_stack_.push_back(MakeEmptyNameContext());
}
auto DeclarationNameStack::Pop() -> NameContext {
auto DeclarationNameStack::FinishName() -> NameContext {
CARBON_CHECK(declaration_name_stack_.back().state !=
NameContext::State::Finished)
<< "Finished name twice";
if (context_->parse_tree().node_kind(
context_->node_stack().PeekParseNode()) ==
Parse::NodeKind::QualifiedDeclaration) {
@@ -39,7 +43,17 @@ auto DeclarationNameStack::Pop() -> NameContext {
ApplyNameQualifier(parse_node, name_id);
}
return declaration_name_stack_.pop_back_val();
NameContext result = declaration_name_stack_.back();
declaration_name_stack_.back().state = NameContext::State::Finished;
return result;
}
auto DeclarationNameStack::PopScope() -> void {
CARBON_CHECK(declaration_name_stack_.back().state ==
NameContext::State::Finished)
<< "Missing call to FinishName before PopScope";
context_->PopToScope(declaration_name_stack_.back().enclosing_scope);
declaration_name_stack_.pop_back();
}
auto DeclarationNameStack::LookupOrAddName(NameContext name_context,
@@ -74,6 +88,9 @@ auto DeclarationNameStack::LookupOrAddName(NameContext name_context,
<< name_context.target_scope_id;
}
return SemIR::InstId::Invalid;
case NameContext::State::Finished:
CARBON_FATAL() << "Finished state should only be used internally";
}
}
@@ -95,16 +112,10 @@ auto DeclarationNameStack::ApplyNameQualifierTo(NameContext& name_context,
IdentifierId name_id) -> void {
if (CanResolveQualifier(name_context, parse_node)) {
// For identifier nodes, we need to perform a lookup on the identifier.
// This means the input instruction name_id is actually a string ID.
//
// TODO: This doesn't perform the right kind of lookup. We will find names
// from enclosing lexical scopes here, in the case where `target_scope_id`
// is invalid.
auto resolved_inst_id = context_->LookupName(
name_context.parse_node, name_id, name_context.target_scope_id,
/*print_diagnostics=*/false);
if (resolved_inst_id == SemIR::InstId::BuiltinError) {
// Invalid indicates an unresolved instruction. Store it and return.
auto resolved_inst_id = context_->LookupNameInDeclaration(
name_context.parse_node, name_id, name_context.target_scope_id);
if (!resolved_inst_id.is_valid()) {
// Invalid indicates an unresolved name. Store it and return.
name_context.state = NameContext::State::Unresolved;
name_context.unresolved_name_id = name_id;
return;
@@ -130,16 +141,19 @@ auto DeclarationNameStack::UpdateScopeIfNeeded(NameContext& name_context)
if (class_info.is_defined()) {
name_context.state = NameContext::State::Resolved;
name_context.target_scope_id = class_info.scope_id;
context_->PushScope(name_context.resolved_inst_id, class_info.scope_id);
} else {
name_context.state = NameContext::State::ResolvedNonScope;
}
break;
}
case SemIR::Namespace::Kind:
case SemIR::Namespace::Kind: {
auto scope_id = resolved_inst.As<SemIR::Namespace>().name_scope_id;
name_context.state = NameContext::State::Resolved;
name_context.target_scope_id =
resolved_inst.As<SemIR::Namespace>().name_scope_id;
name_context.target_scope_id = scope_id;
context_->PushScope(name_context.resolved_inst_id, scope_id);
break;
}
default:
name_context.state = NameContext::State::ResolvedNonScope;
break;
@@ -198,6 +212,9 @@ auto DeclarationNameStack::CanResolveQualifier(NameContext& name_context,
name_context.parse_node = parse_node;
return true;
}
case NameContext::State::Finished:
CARBON_FATAL() << "Added a qualifier after calling FinishName";
}
}