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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`.
42 lines
1.5 KiB
C++
42 lines
1.5 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/pointer_dereference.h"
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#include "llvm/ADT/STLFunctionalExtras.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/check/inst.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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namespace Carbon::Check {
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auto PerformPointerDereference(
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Context& context, Parse::AnyPointerDeferenceExprId node_id,
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SemIR::InstId base_id,
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llvm::function_ref<auto(SemIR::TypeId not_pointer_type_id)->void>
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diagnose_not_pointer) -> SemIR::InstId {
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// TODO: Once we have a finalized design for a pointer interface, use
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//
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// HandleUnaryOperator(context, node_id, {"Pointer", "Dereference"});
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//
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// to convert to a pointer value.
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base_id = ConvertToValueExpr(context, base_id);
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auto type_id = context.types().GetUnqualifiedType(
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context.insts().Get(base_id).type_id());
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auto result_type_id = SemIR::ErrorInst::TypeId;
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if (auto pointer_type =
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context.types().TryGetAs<SemIR::PointerType>(type_id)) {
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result_type_id =
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context.types().GetTypeIdForTypeInstId(pointer_type->pointee_id);
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} else if (type_id != SemIR::ErrorInst::TypeId) {
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diagnose_not_pointer(type_id);
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}
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return AddInst<SemIR::Deref>(
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context, node_id, {.type_id = result_type_id, .pointer_id = base_id});
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}
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} // namespace Carbon::Check
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