/usr/include/spdlog/ is in libspdlog-dev 1:0.16.3-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/spdlog/async_logger.h
/usr/include/spdlog/common.h
/usr/include/spdlog/details/
/usr/include/spdlog/details/async_log_helper.h
/usr/include/spdlog/details/async_logger_impl.h
/usr/include/spdlog/details/file_helper.h
/usr/include/spdlog/details/log_msg.h
/usr/include/spdlog/details/logger_impl.h
/usr/include/spdlog/details/mpmc_bounded_q.h
/usr/include/spdlog/details/null_mutex.h
/usr/include/spdlog/details/os.h
/usr/include/spdlog/details/pattern_formatter_impl.h
/usr/include/spdlog/details/registry.h
/usr/include/spdlog/details/spdlog_impl.h
/usr/include/spdlog/fmt/
/usr/include/spdlog/fmt/bundled/
/usr/include/spdlog/fmt/bundled/format.cc
/usr/include/spdlog/fmt/bundled/format.h
/usr/include/spdlog/fmt/bundled/ostream.cc
/usr/include/spdlog/fmt/bundled/ostream.h
/usr/include/spdlog/fmt/bundled/posix.cc
/usr/include/spdlog/fmt/bundled/posix.h
/usr/include/spdlog/fmt/bundled/printf.cc
/usr/include/spdlog/fmt/bundled/printf.h
/usr/include/spdlog/fmt/bundled/time.h
/usr/include/spdlog/fmt/fmt.h
/usr/include/spdlog/fmt/ostr.h
/usr/include/spdlog/formatter.h
/usr/include/spdlog/logger.h
/usr/include/spdlog/sinks/
/usr/include/spdlog/sinks/android_sink.h
/usr/include/spdlog/sinks/ansicolor_sink.h
/usr/include/spdlog/sinks/base_sink.h
/usr/include/spdlog/sinks/dist_sink.h
/usr/include/spdlog/sinks/file_sinks.h
/usr/include/spdlog/sinks/msvc_sink.h
/usr/include/spdlog/sinks/null_sink.h
/usr/include/spdlog/sinks/ostream_sink.h
/usr/include/spdlog/sinks/sink.h
/usr/include/spdlog/sinks/stdout_sinks.h
/usr/include/spdlog/sinks/syslog_sink.h
/usr/include/spdlog/sinks/wincolor_sink.h
/usr/include/spdlog/sinks/windebug_sink.h
/usr/include/spdlog/spdlog.h
/usr/include/spdlog/tweakme.h