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Niels Lohmann
83b3bc6831
output_vector_adapter, output_stream_adapter and output_string_adapter declared their write_characters(const CharType*, std::size_t) override JSON_HEDLEY_NON_NULL(2), but binary_writer legitimately calls it with a null pointer and length 0 for an empty string or binary value; the type-erased call path only stayed silent under UBSan because the static callee at those call sites is the unattributed virtual base. A nonnull attribute on a definition lets GCC and Clang assume the parameter is non-null inside the function body even when the call is virtual, so this was latent undefined behavior, not just style. Drop the attribute from the three overrides and document the (nullptr, 0) contract on output_adapter_protocol::write_characters. unit-cbor, unit-msgpack, unit-bson and unit-bon8 (which all exercise empty binary/string payloads through the stream and vector/string adapters) pass under -fsanitize=address,undefined,nonnull-attribute. Part of #5709 Signed-off-by: Niels Lohmann <mail@nlohmann.me>