mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-10-04 22:02:52 +01:00
Richard Smith
ce1dd20be2
A couple of minor functional changes here: - We now always create a `name_ref` for the name referred to by the right-hand operand of member access. Previously we skipped creating this instruction if the referenced name was a field, and just created the field access instruction. This makes our processing of member accesses and our SemIR representation a bit more uniform. - We now perform lookup into the type of the left-hand operand if it's any type with a scope, not just for classes. This means we do lookup into interface types. However, doing so isn't really useful yet because it always finds an associated entity that isn't usable by itself. This changes the diagnostic in `toolchain/check/testdata/interface/fail_todo_facet_lookup.carbon`.
251 lines
11 KiB
C++
251 lines
11 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "llvm/ADT/STLExtras.h"
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#include "toolchain/check/context.h"
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#include "toolchain/check/convert.h"
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#include "toolchain/sem_ir/inst.h"
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#include "toolchain/sem_ir/typed_insts.h"
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namespace Carbon::Check {
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// Returns the name scope corresponding to base_id, or nullopt if not a scope.
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// On invalid scopes, prints a diagnostic and still returns the scope.
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static auto GetAsNameScope(Context& context, SemIR::InstId base_id)
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-> std::optional<SemIR::NameScopeId> {
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auto base_const_id = context.constant_values().Get(base_id);
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if (!base_const_id.is_constant()) {
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// A name scope must be a constant.
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return std::nullopt;
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}
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auto base = context.insts().Get(base_const_id.inst_id());
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if (auto base_as_namespace = base.TryAs<SemIR::Namespace>()) {
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return base_as_namespace->name_scope_id;
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}
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// TODO: Consider refactoring the near-identical class and interface support
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// below.
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if (auto base_as_class = base.TryAs<SemIR::ClassType>()) {
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auto& class_info = context.classes().Get(base_as_class->class_id);
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if (!class_info.is_defined()) {
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CARBON_DIAGNOSTIC(QualifiedExprInIncompleteClassScope, Error,
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"Member access into incomplete class `{0}`.",
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std::string);
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auto builder =
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context.emitter().Build(base_id, QualifiedExprInIncompleteClassScope,
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context.sem_ir().StringifyTypeExpr(base_id));
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context.NoteIncompleteClass(base_as_class->class_id, builder);
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builder.Emit();
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}
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return class_info.scope_id;
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}
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if (auto base_as_interface = base.TryAs<SemIR::InterfaceType>()) {
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auto& interface_info =
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context.interfaces().Get(base_as_interface->interface_id);
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if (!interface_info.is_defined()) {
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CARBON_DIAGNOSTIC(QualifiedExprInUndefinedInterfaceScope, Error,
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"Member access into undefined interface `{0}`.",
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std::string);
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auto builder = context.emitter().Build(
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base_id, QualifiedExprInUndefinedInterfaceScope,
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context.sem_ir().StringifyTypeExpr(base_id));
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context.NoteUndefinedInterface(base_as_interface->interface_id, builder);
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builder.Emit();
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}
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return interface_info.scope_id;
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}
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// TODO: Per the design, if `base_id` is any kind of type, then lookup should
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// treat it as a name scope, even if it doesn't have members. For example,
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// `(i32*).X` should fail because there's no name `X` in `i32*`, not because
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// there's no name `X` in `type`.
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return std::nullopt;
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}
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// Returns the index of the specified class element within the class's
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// representation.
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static auto GetClassElementIndex(Context& context, SemIR::InstId element_id)
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-> SemIR::ElementIndex {
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auto element_inst = context.insts().Get(element_id);
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if (auto field = element_inst.TryAs<SemIR::FieldDecl>()) {
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return field->index;
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}
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if (auto base = element_inst.TryAs<SemIR::BaseDecl>()) {
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return base->index;
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}
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CARBON_FATAL() << "Unexpected value " << element_inst
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<< " in class element name";
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}
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// Returns whether `function_id` is an instance method, that is, whether it has
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// an implicit `self` parameter.
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static auto IsInstanceMethod(const SemIR::File& sem_ir,
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SemIR::FunctionId function_id) -> bool {
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const auto& function = sem_ir.functions().Get(function_id);
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for (auto param_id :
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sem_ir.inst_blocks().Get(function.implicit_param_refs_id)) {
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auto param =
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SemIR::Function::GetParamFromParamRefId(sem_ir, param_id).second;
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if (param.name_id == SemIR::NameId::SelfValue) {
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return true;
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}
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}
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return false;
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}
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// Performs a member name lookup into the specified scope. If the scope is
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// invalid, assume an error has already been diagnosed, and return BuiltinError.
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static auto LookupMemberNameInScope(Context& context,
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Parse::MemberAccessExprId node_id,
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SemIR::InstId /*base_id*/,
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SemIR::NameId name_id,
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SemIR::NameScopeId name_scope_id)
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-> SemIR::InstId {
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auto inst_id = name_scope_id.is_valid() ? context.LookupQualifiedName(
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node_id, name_id, name_scope_id)
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: SemIR::InstId::BuiltinError;
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auto inst = context.insts().Get(inst_id);
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// TODO: Use a different kind of instruction that also references the
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// `base_id` so that `SemIR` consumers can find it.
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return context.AddInst(
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{node_id, SemIR::NameRef{inst.type_id(), name_id, inst_id}});
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}
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// Performs the instance binding step in member access. If the found member is a
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// field, forms a class member access. If the found member is an instance
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// method, forms a bound method. Otherwise, the member is returned unchanged.
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static auto PerformInstanceBinding(Context& context,
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Parse::MemberAccessExprId node_id,
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SemIR::InstId base_id,
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SemIR::InstId member_id) -> SemIR::InstId {
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auto member_type_id = context.insts().Get(member_id).type_id();
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if (auto unbound_element_type =
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context.types().TryGetAs<SemIR::UnboundElementType>(member_type_id)) {
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// Convert the base to the type of the element if necessary.
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base_id = ConvertToValueOrRefOfType(context, node_id, base_id,
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unbound_element_type->class_type_id);
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// Find the specified element, which could be either a field or a base
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// class, and build an element access expression.
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auto element_id = context.constant_values().Get(member_id);
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CARBON_CHECK(element_id.is_constant())
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<< "Non-constant value " << context.insts().Get(member_id)
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<< " of unbound element type";
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auto index = GetClassElementIndex(context, element_id.inst_id());
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auto access_id = context.AddInst(
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{node_id, SemIR::ClassElementAccess{
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unbound_element_type->element_type_id, base_id, index}});
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if (SemIR::GetExprCategory(context.sem_ir(), base_id) ==
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SemIR::ExprCategory::Value &&
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SemIR::GetExprCategory(context.sem_ir(), access_id) !=
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SemIR::ExprCategory::Value) {
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// Class element access on a value expression produces an ephemeral
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// reference if the class's value representation is a pointer to the
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// object representation. Add a value binding in that case so that the
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// expression category of the result matches the expression category of
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// the base.
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access_id = ConvertToValueExpr(context, access_id);
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}
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return access_id;
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}
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if (member_type_id ==
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context.GetBuiltinType(SemIR::BuiltinKind::FunctionType)) {
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// Find the named function and check whether it's an instance method.
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auto function_name_id = context.constant_values().Get(member_id);
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CARBON_CHECK(function_name_id.is_constant())
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<< "Non-constant value " << context.insts().Get(member_id)
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<< " of function type";
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auto function_decl = context.insts()
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.Get(function_name_id.inst_id())
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.TryAs<SemIR::FunctionDecl>();
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CARBON_CHECK(function_decl)
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<< "Unexpected value "
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<< context.insts().Get(function_name_id.inst_id())
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<< " of function type";
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if (IsInstanceMethod(context.sem_ir(), function_decl->function_id)) {
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return context.AddInst(
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{node_id, SemIR::BoundMethod{context.GetBuiltinType(
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SemIR::BuiltinKind::BoundMethodType),
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base_id, member_id}});
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}
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}
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// Not an instance member: no instance binding.
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return member_id;
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}
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auto PerformMemberAccess(Context& context, Parse::MemberAccessExprId node_id,
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SemIR::InstId base_id, SemIR::NameId name_id)
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-> SemIR::InstId {
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// If the base is a name scope, such as a class or namespace, perform lookup
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// into that scope.
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if (auto name_scope_id = GetAsNameScope(context, base_id)) {
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return LookupMemberNameInScope(context, node_id, base_id, name_id,
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*name_scope_id);
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}
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// If the base isn't a scope, it must have a complete type.
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auto base_type_id = context.insts().Get(base_id).type_id();
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if (!context.TryToCompleteType(base_type_id, [&] {
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CARBON_DIAGNOSTIC(IncompleteTypeInMemberAccess, Error,
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"Member access into object of incomplete type `{0}`.",
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SemIR::TypeId);
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return context.emitter().Build(base_id, IncompleteTypeInMemberAccess,
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base_type_id);
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})) {
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return SemIR::InstId::BuiltinError;
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}
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// Materialize a temporary for the base expression if necessary.
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base_id = ConvertToValueOrRefExpr(context, base_id);
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base_type_id = context.insts().Get(base_id).type_id();
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auto base_type_inst_id = context.types().GetInstId(base_type_id);
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// Find the scope corresponding to the base type.
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auto name_scope_id = GetAsNameScope(context, base_type_inst_id);
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if (!name_scope_id) {
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// The base type is not a name scope. Try some fallback options.
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if (auto struct_type =
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context.insts().TryGetAs<SemIR::StructType>(base_type_inst_id)) {
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// TODO: Do we need to optimize this with a lookup table for O(1)?
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for (auto [i, ref_id] :
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llvm::enumerate(context.inst_blocks().Get(struct_type->fields_id))) {
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auto field = context.insts().GetAs<SemIR::StructTypeField>(ref_id);
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if (name_id == field.name_id) {
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// TODO: Model this as producing a lookup result, and do instance
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// binding separately. Perhaps a struct type should be a name scope.
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return context.AddInst(
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{node_id, SemIR::StructAccess{field.field_type_id, base_id,
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SemIR::ElementIndex(i)}});
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}
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}
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CARBON_DIAGNOSTIC(QualifiedExprNameNotFound, Error,
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"Type `{0}` does not have a member `{1}`.",
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SemIR::TypeId, SemIR::NameId);
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context.emitter().Emit(node_id, QualifiedExprNameNotFound, base_type_id,
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name_id);
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return SemIR::InstId::BuiltinError;
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}
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if (base_type_id != SemIR::TypeId::Error) {
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CARBON_DIAGNOSTIC(QualifiedExprUnsupported, Error,
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"Type `{0}` does not support qualified expressions.",
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SemIR::TypeId);
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context.emitter().Emit(node_id, QualifiedExprUnsupported, base_type_id);
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}
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return SemIR::InstId::BuiltinError;
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}
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// Perform lookup into the base type.
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auto member_id = LookupMemberNameInScope(context, node_id, base_id, name_id,
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*name_scope_id);
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// Perform instance binding if we found an instance member.
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member_id = PerformInstanceBinding(context, node_id, base_id, member_id);
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return member_id;
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}
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} // namespace Carbon::Check
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