Class error_builder

src/toml.hpp:12918–12952

	}

	struct error_builder
	{
		static constexpr std::size_t buf_size = 512;
		char buf[buf_size];
		char* write_pos			  = buf;
		char* const max_write_pos = buf + (buf_size - std::size_t{ 1 }); // allow for null terminator

		TOML_NODISCARD_CTOR
		error_builder(std::string_view scope) noexcept
		{
			concatenate(write_pos, max_write_pos, "Error while parsing "sv);
			concatenate(write_pos, max_write_pos, scope);
			concatenate(write_pos, max_write_pos, ": "sv);
		}

		template <typename T>
		void append(const T& arg) noexcept
		{
			concatenate(write_pos, max_write_pos, arg);
		}

		TOML_RETURNS_BY_THROWING
		auto finish(const source_position& pos, const source_path_ptr& source_path) const
		{
			*write_pos = '\0';

#if TOML_EXCEPTIONS
			throw parse_error{ buf, pos, source_path };
#else
			return parse_error{ std::string(buf, static_cast<size_t>(write_pos - buf)), pos, source_path };
#endif
		}

		TOML_DELETE_DEFAULTS(error_builder);
	};

	struct parse_scope
	{