CMake error on INSTALL(EXPORT ...) when adding the mqtt_cpp package with CPM.cmake

[lproj]

Hi,

I've already opened a ticket on CPM.cmake regarding the issue below. Feel free to close this issue one if you think it is better to answer there.

With regard to the boost example in the CPM.cmake repository, I am trying to add a package right after the CPMAddPackage(NAME Boost ...) line:

set(MQTT_BUILD_EXAMPLES OFF CACHE BOOL "build mqtt_cpp examples" FORCE)
set(MQTT_BUILD_TESTS OFF CACHE BOOL "build mqtt_cpp tests" FORCE)
cpmaddpackage("gh:redboltz/mqtt_cpp#master")

However, I get this error when trying to build the project with cmake (from Ubuntu 22.04):

-- Configuring done
CMake Error: install(EXPORT "mqtt_cpp_ifaceTargets" ...) includes target "mqtt_cpp_iface" which requires target "boost_system" that is not in any export set.
CMake Error: install(EXPORT "mqtt_cpp_ifaceTargets" ...) includes target "mqtt_cpp_iface" which requires target "boost_date_time" that is not in any export set.

Do you know why this happens? It seems to me that the Boost targets do not get exported for some reasons.

Thanks in advance.

[redboltz]

I'm not sure why it happens but #990 would solve the issue. Please try it.
Boost.System was a normal library but now it is a header-only library. I'm not sure Boost.DataTime is the same situation.
But accoding to your log, only they output the error.

[lproj]

Installing mqtt_cpp#fix_989 works, thanks. I've provided more details as a comment on #990 .

...
-- CPM: Adding package mqtt_cpp@ (fix_989)
-- Setting minimum C++ standard to C++14
-- TLS disabled
-- WebSocket disabled
-- Always send reason code enabled
-- UTF8String check enabled
-- Using boost::variant instead of std::variant
-- Using boost::optional instead of std::optional
-- Using boost::string_view instead of std::string_view
-- Using boost::any instead of std::any
-- Using boost::shared_ptr<char []> instead of std::shared_ptr<char []>
-- std::tuplestd::any workaround for libstdc++ enabled
-- Dynamically linking with Boost
-- Dynamically linking with Openssl
-- Logging disabled
-- Configuring done
-- Generating done
...

[redboltz]

Thanks.
Unfortunately, CI failed. In order to merge #990, CI should be passed.
https://github.com/redboltz/mqtt_cpp/actions/runs/6850513492/job/18624825988?pr=990

I have no time to solve it serveral weeks, sorry.
If someone fix the CI issue, please create the PR based on fix_989 branch.

[redboltz]

I got a time by chance, so I have fixed the CI issue.

[lproj]

Thanks for you help and keep up the good work!