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https://github.com/carbon-language/carbon-lang.git
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Jon Ross-Perkins
4923445e3a
We frequently want to operate on singletons. Per discussion, drop `Singleton` to make the code shorter. This started off as wanting to write `inst_id.is_error()`, but the dependency relationship between ids.h and singleton_insts.h would require some kind of delayed evaluation to allow the implementation to remain in headers (which I suspect is helpful to have for inlining). I could have added something like `IsErrorInst`, forward declared in ids.h and defined in singleton_insts.h (which would always be included by typed_insts.h), but the template approach felt like a decent balance between (a) removing the boilerplate `::SingletonInstId`, (b) understandability, (c) still visually mirroring if we immediately return a singleton, and (d) flexibility for more than just `ErrorInst`. But TBH I'd probably still have written `is_error()` if it didn't require addressing the cross-header cycle. Then I tried `SemIR::InstId::Is<SemIR::ErrorInst>`, which generally worked with types but generated the complaint that it didn't shorten *all* singleton uses. So pulling back on `::Is`, and instead just dropping `Singleton`.
108 lines
4.4 KiB
C++
108 lines
4.4 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 "toolchain/check/context.h"
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#include "toolchain/check/decl_introducer_state.h"
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#include "toolchain/check/handle.h"
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#include "toolchain/check/inst.h"
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#include "toolchain/check/modifiers.h"
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#include "toolchain/check/name_component.h"
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#include "toolchain/check/name_lookup.h"
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#include "toolchain/check/type.h"
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#include "toolchain/sem_ir/ids.h"
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#include "toolchain/sem_ir/inst.h"
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#include "toolchain/sem_ir/name_scope.h"
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#include "toolchain/sem_ir/typed_insts.h"
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namespace Carbon::Check {
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auto HandleParseNode(Context& context, Parse::NamespaceStartId /*node_id*/)
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-> bool {
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// Optional modifiers and the name follow.
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context.decl_introducer_state_stack().Push<Lex::TokenKind::Namespace>();
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context.decl_name_stack().PushScopeAndStartName();
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return true;
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}
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static auto IsNamespaceScope(Context& context, SemIR::NameScopeId name_scope_id)
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-> bool {
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auto [_, inst] = context.name_scopes().GetInstIfValid(name_scope_id);
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return inst && inst->Is<SemIR::Namespace>();
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}
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auto HandleParseNode(Context& context, Parse::NamespaceId node_id) -> bool {
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auto name_context = context.decl_name_stack().FinishName(
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PopNameComponentWithoutParams(context, Lex::TokenKind::Namespace));
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auto introducer =
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context.decl_introducer_state_stack().Pop<Lex::TokenKind::Namespace>();
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LimitModifiersOnDecl(context, introducer, KeywordModifierSet::None);
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auto namespace_inst =
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SemIR::Namespace{GetSingletonType(context, SemIR::NamespaceType::InstId),
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SemIR::NameScopeId::None, SemIR::InstId::None};
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auto namespace_id = AddPlaceholderInst(context, node_id, namespace_inst);
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SemIR::ScopeLookupResult lookup_result =
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context.decl_name_stack().LookupOrAddName(name_context, namespace_id,
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SemIR::AccessKind::Public);
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if (lookup_result.is_poisoned()) {
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DiagnosePoisonedName(context, name_context.name_id_for_new_inst(),
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lookup_result.poisoning_loc_id(), name_context.loc_id);
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} else if (lookup_result.is_found()) {
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SemIR::InstId existing_inst_id = lookup_result.target_inst_id();
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if (auto existing =
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context.insts().TryGetAs<SemIR::Namespace>(existing_inst_id)) {
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// If there's a name conflict with a namespace, "merge" by using the
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// previous declaration. Otherwise, diagnose the issue.
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// Point at the other namespace.
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namespace_inst.name_scope_id = existing->name_scope_id;
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if (context.name_scopes()
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.Get(existing->name_scope_id)
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.is_closed_import()) {
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// The existing name is a package name, so this is a name conflict.
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DiagnoseDuplicateName(context, name_context.name_id,
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name_context.loc_id, existing_inst_id);
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// Treat this as a local namespace name from now on to avoid further
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// diagnostics.
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context.name_scopes()
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.Get(existing->name_scope_id)
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.set_is_closed_import(false);
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} else if (existing->import_id.has_value() &&
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!context.insts().GetLocId(existing_inst_id).has_value()) {
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// When the name conflict is an imported namespace, fill the location ID
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// so that future diagnostics point at this declaration.
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SetNamespaceNodeId(context, existing_inst_id, node_id);
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}
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} else {
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DiagnoseDuplicateName(context, name_context.name_id, name_context.loc_id,
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existing_inst_id);
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}
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}
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// If we weren't able to merge namespaces, add a new name scope. Note this
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// occurs even for duplicates where we discard the namespace, because we want
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// to produce a valid constant.
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if (!namespace_inst.name_scope_id.has_value()) {
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namespace_inst.name_scope_id = context.name_scopes().Add(
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namespace_id, name_context.name_id_for_new_inst(),
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name_context.parent_scope_id);
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if (!IsNamespaceScope(context, name_context.parent_scope_id)) {
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CARBON_DIAGNOSTIC(NamespaceDeclNotAtTopLevel, Error,
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"`namespace` declaration not at top level");
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context.emitter().Emit(node_id, NamespaceDeclNotAtTopLevel);
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}
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}
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ReplaceInstBeforeConstantUse(context, namespace_id, namespace_inst);
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context.decl_name_stack().PopScope();
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return true;
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}
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} // namespace Carbon::Check
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