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Refactor name lookup logic out of Context (#4930)

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This is a pretty straight move of name lookup functionality to
name_lookup.*
This commit is contained in:
Jon Ross-Perkins
2025-02-12 22:03:08 +00:00
committed by GitHub
parent c6d35e1c4a
commit afef6cd940
15 changed files with 622 additions and 576 deletions
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toolchain/check/context.cpp
-463
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@@ -242,28 +242,6 @@ auto Context::DiagnoseNameNotFound(SemIRLoc loc, SemIR::NameId name_id)
emitter_->Emit(loc, NameNotFound, name_id);
}
auto Context::DiagnoseMemberNameNotFound(
SemIRLoc loc, SemIR::NameId name_id,
llvm::ArrayRef<LookupScope> lookup_scopes) -> void {
if (lookup_scopes.size() == 1 &&
lookup_scopes.front().name_scope_id.has_value()) {
auto specific_id = lookup_scopes.front().specific_id;
auto scope_inst_id =
specific_id.has_value()
? GetInstForSpecific(*this, specific_id)
: name_scopes().Get(lookup_scopes.front().name_scope_id).inst_id();
CARBON_DIAGNOSTIC(MemberNameNotFoundInScope, Error,
"member name `{0}` not found in {1}", SemIR::NameId,
InstIdAsType);
emitter_->Emit(loc, MemberNameNotFoundInScope, name_id, scope_inst_id);
return;
}
CARBON_DIAGNOSTIC(MemberNameNotFound, Error, "member name `{0}` not found",
SemIR::NameId);
emitter_->Emit(loc, MemberNameNotFound, name_id);
}
auto Context::NoteAbstractClass(SemIR::ClassId class_id,
DiagnosticBuilder& builder) -> void {
const auto& class_info = classes().Get(class_id);
@@ -306,447 +284,6 @@ auto Context::NoteUndefinedInterface(SemIR::InterfaceId interface_id,
}
}
auto Context::AddNameToLookup(SemIR::NameId name_id, SemIR::InstId target_id,
ScopeIndex scope_index) -> void {
if (auto existing =
scope_stack().LookupOrAddName(name_id, target_id, scope_index);
existing.has_value()) {
DiagnoseDuplicateName(target_id, existing);
}
}
auto Context::LookupNameInDecl(SemIR::LocId loc_id, SemIR::NameId name_id,
SemIR::NameScopeId scope_id,
ScopeIndex scope_index)
-> SemIR::ScopeLookupResult {
if (!scope_id.has_value()) {
// Look for a name in the specified scope or a scope nested within it only.
// There are two cases where the name would be in an outer scope:
//
// - The name is the sole component of the declared name:
//
// class A;
// fn F() {
// class A;
// }
//
// In this case, the inner A is not the same class as the outer A, so
// lookup should not find the outer A.
//
// - The name is a qualifier of some larger declared name:
//
// class A { class B; }
// fn F() {
// class A.B {}
// }
//
// In this case, we're not in the correct scope to define a member of
// class A, so we should reject, and we achieve this by not finding the
// name A from the outer scope.
//
// There is also one case where the name would be in an inner scope:
//
// - The name is redeclared by a parameter of the same entity:
//
// fn F() {
// class C(C:! type);
// }
//
// In this case, the class C is not a redeclaration of its parameter, but
// we find the parameter in order to diagnose a redeclaration error.
return SemIR::ScopeLookupResult::MakeWrappedLookupResult(
scope_stack().LookupInLexicalScopesWithin(name_id, scope_index),
SemIR::AccessKind::Public);
} else {
// We do not look into `extend`ed scopes here. A qualified name in a
// declaration must specify the exact scope in which the name was originally
// introduced:
//
// base class A { fn F(); }
// class B { extend base: A; }
//
// // Error, no `F` in `B`.
// fn B.F() {}
return LookupNameInExactScope(loc_id, name_id, scope_id,
name_scopes().Get(scope_id),
/*is_being_declared=*/true);
}
}
auto Context::LookupUnqualifiedName(Parse::NodeId node_id,
SemIR::NameId name_id, bool required)
-> LookupResult {
// TODO: Check for shadowed lookup results.
// Find the results from ancestor lexical scopes. These will be combined with
// results from non-lexical scopes such as namespaces and classes.
auto [lexical_result, non_lexical_scopes] =
scope_stack().LookupInLexicalScopes(name_id);
// Walk the non-lexical scopes and perform lookups into each of them.
for (auto [index, lookup_scope_id, specific_id] :
llvm::reverse(non_lexical_scopes)) {
if (auto non_lexical_result =
LookupQualifiedName(node_id, name_id,
LookupScope{.name_scope_id = lookup_scope_id,
.specific_id = specific_id},
/*required=*/false);
non_lexical_result.scope_result.is_found()) {
return non_lexical_result;
}
}
if (lexical_result == SemIR::InstId::InitTombstone) {
CARBON_DIAGNOSTIC(UsedBeforeInitialization, Error,
"`{0}` used before initialization", SemIR::NameId);
emitter_->Emit(node_id, UsedBeforeInitialization, name_id);
return {.specific_id = SemIR::SpecificId::None,
.scope_result = SemIR::ScopeLookupResult::MakeError()};
}
if (lexical_result.has_value()) {
// A lexical scope never needs an associated specific. If there's a
// lexically enclosing generic, then it also encloses the point of use of
// the name.
return {.specific_id = SemIR::SpecificId::None,
.scope_result = SemIR::ScopeLookupResult::MakeFound(
lexical_result, SemIR::AccessKind::Public)};
}
// We didn't find anything at all.
if (required) {
DiagnoseNameNotFound(node_id, name_id);
}
return {.specific_id = SemIR::SpecificId::None,
.scope_result = SemIR::ScopeLookupResult::MakeError()};
}
auto Context::LookupNameInExactScope(SemIR::LocId loc_id, SemIR::NameId name_id,
SemIR::NameScopeId scope_id,
SemIR::NameScope& scope,
bool is_being_declared)
-> SemIR::ScopeLookupResult {
if (auto entry_id = is_being_declared
? scope.Lookup(name_id)
: scope.LookupOrPoison(loc_id, name_id)) {
auto lookup_result = scope.GetEntry(*entry_id).result;
if (!lookup_result.is_poisoned()) {
LoadImportRef(*this, lookup_result.target_inst_id());
}
return lookup_result;
}
if (!scope.import_ir_scopes().empty()) {
// TODO: Enforce other access modifiers for imports.
return SemIR::ScopeLookupResult::MakeWrappedLookupResult(
ImportNameFromOtherPackage(*this, loc_id, scope_id,
scope.import_ir_scopes(), name_id),
SemIR::AccessKind::Public);
}
return SemIR::ScopeLookupResult::MakeNotFound();
}
// Prints diagnostics on invalid qualified name access.
static auto DiagnoseInvalidQualifiedNameAccess(Context& context, SemIRLoc loc,
SemIR::InstId scope_result_id,
SemIR::NameId name_id,
SemIR::AccessKind access_kind,
bool is_parent_access,
AccessInfo access_info) -> void {
auto class_type = context.insts().TryGetAs<SemIR::ClassType>(
context.constant_values().GetInstId(access_info.constant_id));
if (!class_type) {
return;
}
// TODO: Support scoped entities other than just classes.
const auto& class_info = context.classes().Get(class_type->class_id);
auto parent_type_id = class_info.self_type_id;
if (access_kind == SemIR::AccessKind::Private && is_parent_access) {
if (auto base_type_id =
class_info.GetBaseType(context.sem_ir(), class_type->specific_id);
base_type_id.has_value()) {
parent_type_id = base_type_id;
} else if (auto adapted_type_id = class_info.GetAdaptedType(
context.sem_ir(), class_type->specific_id);
adapted_type_id.has_value()) {
parent_type_id = adapted_type_id;
} else {
CARBON_FATAL("Expected parent for parent access");
}
}
CARBON_DIAGNOSTIC(
ClassInvalidMemberAccess, Error,
"cannot access {0:private|protected} member `{1}` of type {2}",
BoolAsSelect, SemIR::NameId, SemIR::TypeId);
CARBON_DIAGNOSTIC(ClassMemberDeclaration, Note, "declared here");
context.emitter()
.Build(loc, ClassInvalidMemberAccess,
access_kind == SemIR::AccessKind::Private, name_id, parent_type_id)
.Note(scope_result_id, ClassMemberDeclaration)
.Emit();
}
// Returns whether the access is prohibited by the access modifiers.
static auto IsAccessProhibited(std::optional<AccessInfo> access_info,
SemIR::AccessKind access_kind,
bool is_parent_access) -> bool {
if (!access_info) {
return false;
}
switch (access_kind) {
case SemIR::AccessKind::Public:
return false;
case SemIR::AccessKind::Protected:
return access_info->highest_allowed_access == SemIR::AccessKind::Public;
case SemIR::AccessKind::Private:
return access_info->highest_allowed_access !=
SemIR::AccessKind::Private ||
is_parent_access;
}
}
// Information regarding a prohibited access.
struct ProhibitedAccessInfo {
// The resulting inst of the lookup.
SemIR::InstId scope_result_id;
// The access kind of the lookup.
SemIR::AccessKind access_kind;
// If the lookup is from an extended scope. For example, if this is a base
// class member access from a class that extends it.
bool is_parent_access;
};
auto Context::AppendLookupScopesForConstant(
SemIR::LocId loc_id, SemIR::ConstantId base_const_id,
llvm::SmallVector<LookupScope>* scopes) -> bool {
auto base_id = constant_values().GetInstId(base_const_id);
auto base = insts().Get(base_id);
if (auto base_as_namespace = base.TryAs<SemIR::Namespace>()) {
scopes->push_back(
LookupScope{.name_scope_id = base_as_namespace->name_scope_id,
.specific_id = SemIR::SpecificId::None});
return true;
}
if (auto base_as_class = base.TryAs<SemIR::ClassType>()) {
RequireDefinedType(
*this, GetTypeIdForTypeConstant(base_const_id), loc_id, [&] {
CARBON_DIAGNOSTIC(QualifiedExprInIncompleteClassScope, Error,
"member access into incomplete class {0}",
InstIdAsType);
return emitter().Build(loc_id, QualifiedExprInIncompleteClassScope,
base_id);
});
auto& class_info = classes().Get(base_as_class->class_id);
scopes->push_back(LookupScope{.name_scope_id = class_info.scope_id,
.specific_id = base_as_class->specific_id});
return true;
}
if (auto base_as_facet_type = base.TryAs<SemIR::FacetType>()) {
RequireDefinedType(
*this, GetTypeIdForTypeConstant(base_const_id), loc_id, [&] {
CARBON_DIAGNOSTIC(QualifiedExprInUndefinedInterfaceScope, Error,
"member access into undefined interface {0}",
InstIdAsType);
return emitter().Build(loc_id, QualifiedExprInUndefinedInterfaceScope,
base_id);
});
const auto& facet_type_info =
facet_types().Get(base_as_facet_type->facet_type_id);
for (auto interface : facet_type_info.impls_constraints) {
auto& interface_info = interfaces().Get(interface.interface_id);
scopes->push_back(LookupScope{.name_scope_id = interface_info.scope_id,
.specific_id = interface.specific_id});
}
return true;
}
if (base_const_id == SemIR::ErrorInst::SingletonConstantId) {
// Lookup into this scope should fail without producing an error.
scopes->push_back(LookupScope{.name_scope_id = SemIR::NameScopeId::None,
.specific_id = SemIR::SpecificId::None});
return true;
}
// TODO: Per the design, if `base_id` is any kind of type, then lookup should
// treat it as a name scope, even if it doesn't have members. For example,
// `(i32*).X` should fail because there's no name `X` in `i32*`, not because
// there's no name `X` in `type`.
return false;
}
auto Context::LookupQualifiedName(SemIR::LocId loc_id, SemIR::NameId name_id,
llvm::ArrayRef<LookupScope> lookup_scopes,
bool required,
std::optional<AccessInfo> access_info)
-> LookupResult {
llvm::SmallVector<LookupScope> scopes(lookup_scopes);
// TODO: Support reporting of multiple prohibited access.
llvm::SmallVector<ProhibitedAccessInfo> prohibited_accesses;
LookupResult result = {
.specific_id = SemIR::SpecificId::None,
.scope_result = SemIR::ScopeLookupResult::MakeNotFound()};
bool has_error = false;
bool is_parent_access = false;
// Walk this scope and, if nothing is found here, the scopes it extends.
while (!scopes.empty()) {
auto [scope_id, specific_id] = scopes.pop_back_val();
if (!scope_id.has_value()) {
has_error = true;
continue;
}
auto& name_scope = name_scopes().Get(scope_id);
has_error |= name_scope.has_error();
const SemIR::ScopeLookupResult scope_result =
LookupNameInExactScope(loc_id, name_id, scope_id, name_scope);
SemIR::AccessKind access_kind = scope_result.access_kind();
auto is_access_prohibited =
IsAccessProhibited(access_info, access_kind, is_parent_access);
// Keep track of prohibited accesses, this will be useful for reporting
// multiple prohibited accesses if we can't find a suitable lookup.
if (is_access_prohibited) {
prohibited_accesses.push_back({
.scope_result_id = scope_result.target_inst_id(),
.access_kind = access_kind,
.is_parent_access = is_parent_access,
});
}
if (!scope_result.is_found() || is_access_prohibited) {
// If nothing is found in this scope or if we encountered an invalid
// access, look in its extended scopes.
const auto& extended = name_scope.extended_scopes();
scopes.reserve(scopes.size() + extended.size());
for (auto extended_id : llvm::reverse(extended)) {
// Substitute into the constant describing the extended scope to
// determine its corresponding specific.
CARBON_CHECK(extended_id.has_value());
LoadImportRef(*this, extended_id);
SemIR::ConstantId const_id =
GetConstantValueInSpecific(sem_ir(), specific_id, extended_id);
DiagnosticAnnotationScope annotate_diagnostics(
&emitter(), [&](auto& builder) {
CARBON_DIAGNOSTIC(FromExtendHere, Note,
"declared as an extended scope here");
builder.Note(extended_id, FromExtendHere);
});
if (!AppendLookupScopesForConstant(loc_id, const_id, &scopes)) {
// TODO: Handle case where we have a symbolic type and instead should
// look in its type.
}
}
is_parent_access |= !extended.empty();
continue;
}
// If this is our second lookup result, diagnose an ambiguity.
if (result.scope_result.is_found()) {
CARBON_DIAGNOSTIC(
NameAmbiguousDueToExtend, Error,
"ambiguous use of name `{0}` found in multiple extended scopes",
SemIR::NameId);
emitter_->Emit(loc_id, NameAmbiguousDueToExtend, name_id);
// TODO: Add notes pointing to the scopes.
return {.specific_id = SemIR::SpecificId::None,
.scope_result = SemIR::ScopeLookupResult::MakeError()};
}
result.scope_result = scope_result;
result.specific_id = specific_id;
}
if (required && !result.scope_result.is_found()) {
if (!has_error) {
if (prohibited_accesses.empty()) {
DiagnoseMemberNameNotFound(loc_id, name_id, lookup_scopes);
} else {
// TODO: We should report multiple prohibited accesses in case we don't
// find a valid lookup. Reporting the last one should suffice for now.
auto [scope_result_id, access_kind, is_parent_access] =
prohibited_accesses.back();
// Note, `access_info` is guaranteed to have a value here, since
// `prohibited_accesses` is non-empty.
DiagnoseInvalidQualifiedNameAccess(*this, loc_id, scope_result_id,
name_id, access_kind,
is_parent_access, *access_info);
}
}
CARBON_CHECK(!result.scope_result.is_poisoned());
return {.specific_id = SemIR::SpecificId::None,
.scope_result = SemIR::ScopeLookupResult::MakeError()};
}
return result;
}
// Returns the scope of the Core package, or `None` if it's not found.
//
// TODO: Consider tracking the Core package in SemIR so we don't need to use
// name lookup to find it.
static auto GetCorePackage(Context& context, SemIR::LocId loc_id,
llvm::StringRef name) -> SemIR::NameScopeId {
auto packaging = context.parse_tree().packaging_decl();
if (packaging && packaging->names.package_id == PackageNameId::Core) {
return SemIR::NameScopeId::Package;
}
auto core_name_id = SemIR::NameId::Core;
// Look up `package.Core`.
auto core_scope_result = context.LookupNameInExactScope(
loc_id, core_name_id, SemIR::NameScopeId::Package,
context.name_scopes().Get(SemIR::NameScopeId::Package));
if (core_scope_result.is_found()) {
// We expect it to be a namespace.
if (auto namespace_inst = context.insts().TryGetAs<SemIR::Namespace>(
core_scope_result.target_inst_id())) {
// TODO: Decide whether to allow the case where `Core` is not a package.
return namespace_inst->name_scope_id;
}
}
CARBON_DIAGNOSTIC(
CoreNotFound, Error,
"`Core.{0}` implicitly referenced here, but package `Core` not found",
std::string);
context.emitter().Emit(loc_id, CoreNotFound, name.str());
return SemIR::NameScopeId::None;
}
auto Context::LookupNameInCore(SemIR::LocId loc_id, llvm::StringRef name)
-> SemIR::InstId {
auto core_package_id = GetCorePackage(*this, loc_id, name);
if (!core_package_id.has_value()) {
return SemIR::ErrorInst::SingletonInstId;
}
auto name_id = SemIR::NameId::ForIdentifier(identifiers().Add(name));
auto scope_result = LookupNameInExactScope(
loc_id, name_id, core_package_id, name_scopes().Get(core_package_id));
if (!scope_result.is_found()) {
CARBON_DIAGNOSTIC(
CoreNameNotFound, Error,
"name `Core.{0}` implicitly referenced here, but not found",
SemIR::NameId);
emitter_->Emit(loc_id, CoreNameNotFound, name_id);
return SemIR::ErrorInst::SingletonInstId;
}
// Look through import_refs and aliases.
return constant_values().GetConstantInstId(scope_result.target_inst_id());
}
auto Context::Finalize() -> void {
// Pop information for the file-level scope.
sem_ir().set_top_inst_block_id(inst_block_stack().Pop());