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https://github.com/carbon-language/carbon-lang.git
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Richard Smith
c0b24047dd
Add a new builtin function `cpp.std.initializer_list.make` that takes an array and returns a `std::initializer_list`, initialized to refer to that array. When C++ initialization wants to perform a `std::initializer_list`-from-array construction, synthesize a declaration of a matching builtin function and use that to perform the initialization. Ideally we would specify this conversion as an impl of `ImplicitAs` in the prelude instead of hardcoding it in the interop layer, but unfortunately that's not currently possible, for various reasons -- we can't make the conversion form-generic, we can't deduce the array length from the initializer, and we can't deduce against the arguments of imported C++ class templates yet -- so for now synthesizing a builtin function on demand is the best we can do. Assisted-by: Gemini 3 Pro via Antigravity
55 lines
1.9 KiB
C++
55 lines
1.9 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/sem_ir/cpp_initializer_list.h"
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#include "toolchain/sem_ir/file.h"
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#include "toolchain/sem_ir/inst_categories.h"
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#include "toolchain/sem_ir/typed_insts.h"
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namespace Carbon::SemIR {
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auto GetStdInitializerListLayout(const File& sem_ir, TypeId type_id)
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-> StdInitializerListLayout {
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auto repr_id = sem_ir.types().GetObjectRepr(type_id);
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if (!repr_id.has_value()) {
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// An incomplete type doesn't have a recognized layout.
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return StdInitializerListLayout{};
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}
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auto struct_type = sem_ir.types().TryGetAs<AnyStructType>(repr_id);
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if (!struct_type) {
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return StdInitializerListLayout{};
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}
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auto fields = sem_ir.struct_type_fields().Get(struct_type->fields_id);
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if (fields.size() != 2) {
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return StdInitializerListLayout{};
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}
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// The first field must be a pointer.
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auto field0_type_id = sem_ir.types().GetTransitiveUnqualifiedAdaptedType(
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sem_ir.types().GetTypeIdForTypeInstId(fields[0].type_inst_id));
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if (!sem_ir.types().Is<PointerType>(field0_type_id.first)) {
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return StdInitializerListLayout{};
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}
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// The second field can be either a pointer or an integer.
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auto field1_type_id = sem_ir.types().GetTransitiveUnqualifiedAdaptedType(
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sem_ir.types().GetTypeIdForTypeInstId(fields[1].type_inst_id));
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if (sem_ir.types().Is<PointerType>(field1_type_id.first)) {
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return StdInitializerListLayout{
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.kind = StdInitializerListLayout::PointerPointer};
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}
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if (sem_ir.types().TryGetIntTypeInfo(field1_type_id.first)) {
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return StdInitializerListLayout{
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.kind = StdInitializerListLayout::PointerInt,
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.size_type_id = field1_type_id.first};
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}
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return StdInitializerListLayout{};
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}
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} // namespace Carbon::SemIR
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