Issue with latest release on Bullseye

[xianrecords2015]

I am running Bullseye on a Raspberry PI. Prior to 2 weeks ago, I had no issue with compiling my program with that install of MQTT and now, I am getting the following error messages:

g++ -c -o corinmqtt.o corinmqtt.cpp -I/usr/include/boost -I/home/pi/commmodule/spdlog/include -Wall -g -Wno-narrowing -DPAHO_BUILD_SAMPLES=FALSE
In file included from /usr/local/include/mqtt/message.h:34,
from /usr/local/include/mqtt/delivery_token.h:30,
from /usr/local/include/mqtt/callback.h:31,
from /usr/local/include/mqtt/async_client.h:45,
from corinmqtt.h:11,
from corinmqtt.cpp:1:
/usr/local/include/mqtt/properties.h:101:57: error: ‘string_view’ is not a member of ‘std’
101 | PAHO_MQTTPP_EXPORT static const std::map<code, std::string_view> TYPE_NAME;
| ^~~~~~~~~~~
/usr/local/include/mqtt/properties.h:101:57: note: ‘std::string_view’ is only available from C++17 onwards
/usr/local/include/mqtt/properties.h:101:57: error: ‘string_view’ is not a member of ‘std’
/usr/local/include/mqtt/properties.h:101:57: note: ‘std::string_view’ is only available from C++17 onwards
/usr/local/include/mqtt/properties.h:101:68: error: template argument 2 is invalid
101 | PAHO_MQTTPP_EXPORT static const std::map<code, std::string_view> TYPE_NAME;
| ^
/usr/local/include/mqtt/properties.h:101:68: error: template argument 4 is invalid
/usr/local/include/mqtt/properties.h:184:10: error: ‘string_view’ in namespace ‘std’ does not name a type
184 | std::string_view type_name() const;
| ^~~~~~~~~~~
/usr/local/include/mqtt/properties.h:184:5: note: ‘std::string_view’ is only available from C++17 onwards
184 | std::string_view type_name() const;
| ^~~
In file included from /usr/local/include/mqtt/async_client.h:46,
from corinmqtt.h:11,
from corinmqtt.cpp:1:
/usr/local/include/mqtt/create_options.h:52:31: error: ‘variant’ in namespace ‘std’ does not name a template type
52 | using persistence_type = std::variant<no_persistence, string, iclient_persistence*>;
| ^~~~~~~

[fpagliughi]

The code is moving forward. As the README states...

The latest update moves the code base to C++17

and required tools:

A fully-compatible C++17 compiler

If I'm not mistaken, Bullseye shipped gcc v10, which default to C++14. To tell it to use the correct version, add the compiler flag:

-std=c++17