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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`.
75 lines
3.0 KiB
C++
75 lines
3.0 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/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/parse/node_ids.h"
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#include "toolchain/sem_ir/ids.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::AliasIntroducerId /*node_id*/)
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-> bool {
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context.decl_introducer_state_stack().Push<Lex::TokenKind::Alias>();
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context.decl_name_stack().PushScopeAndStartName();
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return true;
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}
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auto HandleParseNode(Context& /*context*/,
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Parse::AliasInitializerId /*node_id*/) -> bool {
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return true;
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}
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auto HandleParseNode(Context& context, Parse::AliasId /*node_id*/) -> bool {
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auto [expr_node, expr_id] = context.node_stack().PopExprWithNodeId();
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auto name_context = context.decl_name_stack().FinishName(
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PopNameComponentWithoutParams(context, Lex::TokenKind::Alias));
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auto introducer =
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context.decl_introducer_state_stack().Pop<Lex::TokenKind::Alias>();
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LimitModifiersOnDecl(context, introducer, KeywordModifierSet::Access);
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auto entity_name_id = context.entity_names().Add(
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{.name_id = name_context.name_id_for_new_inst(),
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.parent_scope_id = name_context.parent_scope_id});
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auto alias_type_id = SemIR::TypeId::None;
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auto alias_value_id = SemIR::InstId::None;
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if (SemIR::IsSingletonInstId(expr_id)) {
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// Type (`bool`) and value (`false`) literals provided by the builtin
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// structure should be turned into name references.
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// TODO: Look into handling `false`, this doesn't do it right now because it
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// sees a value instruction instead of a builtin.
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alias_type_id = context.insts().Get(expr_id).type_id();
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alias_value_id = expr_id;
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} else if (auto inst = context.insts().TryGetAs<SemIR::NameRef>(expr_id)) {
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// Pass through name references, albeit changing the name in use.
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alias_type_id = inst->type_id;
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alias_value_id = inst->value_id;
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} else {
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CARBON_DIAGNOSTIC(AliasRequiresNameRef, Error,
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"alias initializer must be a name reference");
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context.emitter().Emit(expr_node, AliasRequiresNameRef);
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alias_type_id = SemIR::ErrorInst::TypeId;
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alias_value_id = SemIR::ErrorInst::InstId;
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}
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auto alias_id = AddInst<SemIR::BindAlias>(context, name_context.loc_id,
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{.type_id = alias_type_id,
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.entity_name_id = entity_name_id,
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.value_id = alias_value_id});
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// Add the name of the binding to the current scope.
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context.decl_name_stack().PopScope();
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context.decl_name_stack().AddNameOrDiagnose(
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name_context, alias_id, introducer.modifier_set.GetAccessKind());
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return true;
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}
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} // namespace Carbon::Check
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