Custom functions broken on Linux

[jberkel]

Caused by this bug in Swift:

apple/swift#47006

Not much we can do at this point, except avoiding this construct.

* thread #1, name = 'SQLite.swiftPac', stop reason = signal SIGSEGV: invalid address (fault address: 0x50)
  * frame #0: 0x00007ffff7e1945c libswiftCore.so`swift::MetadataCacheEntryBase<(anonymous namespace)::TupleCacheEntry, swift::TargetTupleTypeMetadata<swift::InProcess>::Element>::doInitialization(swift::ConcurrencyControl&, swift::MetadataCompletionQueueEntry*, swift::MetadataRequest) + 380
    frame #1: 0x00007ffff7e0ad4d libswiftCore.so`std::pair<(anonymous namespace)::TupleCacheEntry*, swift::MetadataResponse> swift::LockingConcurrentMap<(anonymous namespace)::TupleCacheEntry, (anonymous namespace)::TupleCacheStorage>::getOrInsert<(anonymous namespace)::TupleCacheEntry::Key, swift::MetadataRequest&, swift::TargetValueWitnessTable<swift::InProcess> const*&>((anonymous namespace)::TupleCacheEntry::Key, swift::MetadataRequest&, swift::TargetValueWitnessTable<swift::InProcess> const*&) + 3373
    frame #2: 0x00007ffff7e09c7a libswiftCore.so`swift_getTupleTypeMetadata + 250
    frame #3: 0x00007ffff7e270b9 libswiftCore.so`swift::Demangle::__runtime::TypeDecoder<(anonymous namespace)::DecodedMetadataBuilder>::decodeMangledType(swift::Demangle::__runtime::Node*) + 9945
    frame #4: 0x00007ffff7e25467 libswiftCore.so`swift::Demangle::__runtime::TypeDecoder<(anonymous namespace)::DecodedMetadataBuilder>::decodeMangledType(swift::Demangle::__runtime::Node*) + 2695
    frame #5: 0x00007ffff7e24115 libswiftCore.so`swift_getTypeByMangledNodeImpl(swift::MetadataRequest, swift::Demangle::__runtime::Demangler&, swift::Demangle::__runtime::Node*, void const* const*, std::function<swift::TargetMetadata<swift::InProcess> const* (unsigned int, unsigned int)>, std::function<swift::TargetWitnessTable<swift::InProcess> const* (swift::TargetMetadata<swift::InProcess> const*, unsigned int)>) + 437
    frame #6: 0x00007ffff7e23f10 libswiftCore.so`swift::swift_getTypeByMangledNode(swift::MetadataRequest, swift::Demangle::__runtime::Demangler&, swift::Demangle::__runtime::Node*, void const* const*, std::function<swift::TargetMetadata<swift::InProcess> const* (unsigned int, unsigned int)>, std::function<swift::TargetWitnessTable<swift::InProcess> const* (swift::TargetMetadata<swift::InProcess> const*, unsigned int)>) + 384
    frame #7: 0x00007ffff7e24636 libswiftCore.so`swift_getTypeByMangledNameImpl(swift::MetadataRequest, __swift::__runtime::llvm::StringRef, void const* const*, std::function<swift::TargetMetadata<swift::InProcess> const* (unsigned int, unsigned int)>, std::function<swift::TargetWitnessTable<swift::InProcess> const* (swift::TargetMetadata<swift::InProcess> const*, unsigned int)>) + 1046
    frame #8: 0x00007ffff7e21ec0 libswiftCore.so`swift::swift_getTypeByMangledName(swift::MetadataRequest, __swift::__runtime::llvm::StringRef, void const* const*, std::function<swift::TargetMetadata<swift::InProcess> const* (unsigned int, unsigned int)>, std::function<swift::TargetWitnessTable<swift::InProcess> const* (swift::TargetMetadata<swift::InProcess> const*, unsigned int)>) + 384
    frame #9: 0x00007ffff7e220fa libswiftCore.so`swift_getTypeByMangledNameInContext + 170
    frame #10: 0x000055555557a7dd SQLite.swiftPackageTests.xctest`__swift_instantiateConcreteTypeFromMangledName at <compiler-generated>:0
    frame #11: 0x000055555558214f SQLite.swiftPackageTests.xctest`Connection.createFunction(function="test", argumentCount=2, deterministic=true, block=0x00005555555b8a80 SQLite.swiftPackageTests.xctest`partial apply forwarder for closure #1 (Swift.Array<Swift.Optional<SQLite.Binding>>) -> Swift.Optional<SQLite.Binding> in SQLite.Connection.createFunction<A where A: SQLite.Value>(Swift.String, Swift.UInt, Swift.Bool, (Swift.Array<Swift.Optional<SQLite.Binding>>) -> Swift.Optional<A>) throws -> (Swift.Array<SQLite.Expressible>) -> SQLite.Expression<Swift.Optional<A>> at <compiler-generated>, self=0x0000555555a01050) at Connection.swift:643:35
    frame #12: 0x00005555555afb75 SQLite.swiftPackageTests.xctest`Connection.createFunction<Z>(function="test", argumentCount=2, deterministic=true, block=0x5555555b5100, self=0x0000555555a01050) at CustomFunctions.swift:154:9
    frame #13: 0x00005555555b4c3c SQLite.swiftPackageTests.xctest`Connection.createFunction<Z, A, B>(function="test", deterministic=true, block=0x555555645470, self=0x0000555555a01050) at CustomFunctions.swift:120:22
    frame #14: 0x0000555555644b6e SQLite.swiftPackageTests.xctest`CustomFunctionWithTwoArgsTests.testFunctionLeftResultOptional(self=0x0000555555867d20) at CustomFunctionsTests.swift:115:53