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https://github.com/carbon-language/carbon-lang.git
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Avoid crashing if a C++ type was used to look for an IntFitsIn witness (#6924)
Originally this was handled in LookupCppImpl in the switch on the CoreInterface, but in subsequent refactorings it was lost, and we now assume we are always looking for a C++ witness and CHECK that the interface is not `IntFitsIn`. Refactor LookupCppImpl to have a single switch up front on the CoreInterface enum, instead of multiple. It's a quick early out for `IntFitsIn` and delegates work to helper functions specific to each other CoreInterface value.
This commit is contained in:
Dana Jansens
@@ -50,80 +50,27 @@ static auto TypeAsClassDecl(Context& context,
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}
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namespace {
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// See `GetDeclForCoreInterface`.
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struct DeclInfo {
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clang::NamedDecl* decl;
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// If null, no C++ decl was found and no witness can be created.
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clang::NamedDecl* decl = nullptr;
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SemIR::ClangDeclKey::Signature signature;
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};
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} // namespace
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// Retrieves a `core_interface`'s corresponding `NamedDecl`, also with the
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// expected number of parameters. May return a null decl to indicate nothing was
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// found, or nullopt to indicate `SemIR::ErrInst::InstId` should be propagated.
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auto GetDeclForCoreInterface(Context& context, SemIR::LocId loc_id,
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CoreInterface core_interface,
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clang::CXXRecordDecl* class_decl)
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-> std::optional<DeclInfo> {
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auto& clang_sema = context.clang_sema();
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CARBON_CHECK(class_decl != nullptr);
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// TODO: Handle other interfaces.
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switch (core_interface) {
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case CoreInterface::Copy:
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return DeclInfo{.decl = clang_sema.LookupCopyingConstructor(
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class_decl, clang::Qualifiers::Const),
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.signature = {.num_params = 1}};
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case CoreInterface::Destroy:
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return DeclInfo{.decl = clang_sema.LookupDestructor(class_decl),
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.signature = {.num_params = 0}};
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case CoreInterface::CppUnsafeDeref: {
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auto candidates = class_decl->lookup(
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clang_sema.getASTContext().DeclarationNames.getCXXOperatorName(
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clang::OO_Star));
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if (candidates.empty()) {
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return DeclInfo{};
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}
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if (!candidates.isSingleResult()) {
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context.TODO(loc_id, "operator* overload sets not implemented yet");
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return std::nullopt;
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}
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return DeclInfo{.decl = *candidates.begin(),
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.signature = {.num_params = 0}};
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}
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case CoreInterface::IntFitsIn:
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case CoreInterface::Unknown:
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CARBON_FATAL("shouldn't be called with `{}`", core_interface);
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}
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}
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auto LookupCppImpl(Context& context, SemIR::LocId loc_id,
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CoreInterface core_interface,
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SemIR::ConstantId query_self_const_id,
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SemIR::SpecificInterfaceId query_specific_interface_id,
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const TypeStructure* best_impl_type_structure,
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SemIR::LocId best_impl_loc_id) -> SemIR::InstId {
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// TODO: This should provide `Destroy` for enums and other trivially
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// destructible types.
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auto* class_decl = TypeAsClassDecl(context, query_self_const_id);
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if (!class_decl) {
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// Given a DeclInfo of the C++ function to call that will act as an impl for a
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// specific interface, construct a custom witness for that function.
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static auto BuildWitnessForDeclInfo(
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Context& context, SemIR::LocId loc_id, DeclInfo decl_info,
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SemIR::ConstantId query_self_const_id,
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SemIR::SpecificInterfaceId query_specific_interface_id,
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const TypeStructure* best_impl_type_structure,
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SemIR::LocId best_impl_loc_id) -> SemIR::InstId {
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if (!decl_info.decl) {
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// The C++ type is not able to implement the interface.
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return SemIR::InstId::None;
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}
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auto decl_info =
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GetDeclForCoreInterface(context, loc_id, core_interface, class_decl);
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if (!decl_info.has_value()) {
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return SemIR::ErrorInst::InstId;
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}
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if (!decl_info->decl) {
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// TODO: If the impl lookup failure is an error, we should produce a
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// diagnostic explaining why the class does not satisfy the core interface.
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return SemIR::InstId::None;
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}
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auto* cpp_fn = cast<clang::FunctionDecl>(decl_info->decl);
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auto* cpp_fn = cast<clang::FunctionDecl>(decl_info.decl);
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if (context.clang_sema().DiagnoseUseOfOverloadedDecl(
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cpp_fn, GetCppLocation(context, loc_id))) {
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@@ -131,7 +78,7 @@ auto LookupCppImpl(Context& context, SemIR::LocId loc_id,
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}
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auto fn_id =
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ImportCppFunctionDecl(context, loc_id, cpp_fn, decl_info->signature);
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ImportCppFunctionDecl(context, loc_id, cpp_fn, decl_info.signature);
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if (fn_id == SemIR::ErrorInst::InstId) {
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return SemIR::ErrorInst::InstId;
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}
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@@ -148,4 +95,105 @@ auto LookupCppImpl(Context& context, SemIR::LocId loc_id,
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query_specific_interface_id, {fn_id});
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}
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static auto BuildCopyWitness(
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Context& context, SemIR::LocId loc_id,
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SemIR::ConstantId query_self_const_id,
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SemIR::SpecificInterfaceId query_specific_interface_id,
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const TypeStructure* best_impl_type_structure,
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SemIR::LocId best_impl_loc_id) -> SemIR::InstId {
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auto& clang_sema = context.clang_sema();
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// TODO: This should provide `Copy` for enums and other trivially copyable
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// types.
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auto* class_decl = TypeAsClassDecl(context, query_self_const_id);
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if (!class_decl) {
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return SemIR::InstId::None;
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}
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auto decl_info = DeclInfo{.decl = clang_sema.LookupCopyingConstructor(
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class_decl, clang::Qualifiers::Const),
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.signature = {.num_params = 1}};
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return BuildWitnessForDeclInfo(
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context, loc_id, decl_info, query_self_const_id,
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query_specific_interface_id, best_impl_type_structure, best_impl_loc_id);
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}
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static auto BuildDestroyWitness(
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Context& context, SemIR::LocId loc_id,
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SemIR::ConstantId query_self_const_id,
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SemIR::SpecificInterfaceId query_specific_interface_id,
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const TypeStructure* best_impl_type_structure,
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SemIR::LocId best_impl_loc_id) -> SemIR::InstId {
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auto& clang_sema = context.clang_sema();
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// TODO: This should provide `Destroy` for enums and other trivially
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// destructible types.
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auto* class_decl = TypeAsClassDecl(context, query_self_const_id);
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if (!class_decl) {
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return SemIR::InstId::None;
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}
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auto decl_info = DeclInfo{.decl = clang_sema.LookupDestructor(class_decl),
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.signature = {.num_params = 0}};
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return BuildWitnessForDeclInfo(
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context, loc_id, decl_info, query_self_const_id,
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query_specific_interface_id, best_impl_type_structure, best_impl_loc_id);
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}
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static auto BuildCppUnsafeDerefWitness(
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Context& context, SemIR::LocId loc_id,
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SemIR::ConstantId query_self_const_id,
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SemIR::SpecificInterfaceId query_specific_interface_id,
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const TypeStructure* best_impl_type_structure,
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SemIR::LocId best_impl_loc_id) -> SemIR::InstId {
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auto& clang_sema = context.clang_sema();
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auto* class_decl = TypeAsClassDecl(context, query_self_const_id);
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if (!class_decl) {
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return SemIR::InstId::None;
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}
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auto candidates = class_decl->lookup(
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clang_sema.getASTContext().DeclarationNames.getCXXOperatorName(
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clang::OO_Star));
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if (candidates.empty()) {
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return SemIR::InstId::None;
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}
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if (!candidates.isSingleResult()) {
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context.TODO(loc_id, "operator* overload sets not implemented yet");
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return SemIR::ErrorInst::InstId;
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}
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auto decl_info =
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DeclInfo{.decl = *candidates.begin(), .signature = {.num_params = 0}};
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return BuildWitnessForDeclInfo(
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context, loc_id, decl_info, query_self_const_id,
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query_specific_interface_id, best_impl_type_structure, best_impl_loc_id);
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}
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auto LookupCppImpl(Context& context, SemIR::LocId loc_id,
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CoreInterface core_interface,
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SemIR::ConstantId query_self_const_id,
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SemIR::SpecificInterfaceId query_specific_interface_id,
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const TypeStructure* best_impl_type_structure,
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SemIR::LocId best_impl_loc_id) -> SemIR::InstId {
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switch (core_interface) {
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case CoreInterface::Copy:
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return BuildCopyWitness(context, loc_id, query_self_const_id,
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query_specific_interface_id,
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best_impl_type_structure, best_impl_loc_id);
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case CoreInterface::Destroy:
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return BuildDestroyWitness(context, loc_id, query_self_const_id,
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query_specific_interface_id,
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best_impl_type_structure, best_impl_loc_id);
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case CoreInterface::CppUnsafeDeref:
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return BuildCppUnsafeDerefWitness(
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context, loc_id, query_self_const_id, query_specific_interface_id,
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best_impl_type_structure, best_impl_loc_id);
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// IntFitsIn is for Carbon integer types only.
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case CoreInterface::IntFitsIn:
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return SemIR::InstId::None;
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case CoreInterface::Unknown:
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CARBON_FATAL("unexpected CoreInterface `{0}`", core_interface);
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}
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}
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} // namespace Carbon::Check
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