Compile error on ubuntu: error: ‘format’ is not a constant expression

[d3cod3]

I've having a compile error on ubuntu boxes while trying to compile a custom chat application.
The problem came from the logger->warn("Public address changed: {}", addrs); line inside the getDhtConfig method ( copied from dhtchat.cpp example )

/usr/include/opendht/logger.h: In instantiation of ‘void dht::log::Logger::warn(S&&, Args&& ...) const [with S = const char (&)[27]; Args = {std::vector<dht::SockAddr, std::allocator<dht::SockAddr> >&}]’:
/home/user/Development/of_v0.12.0_linux64gcc6_release_Mosaic/addons/ofxOpenDHT/src/ofxOpenDHT.cpp:167:25:   required from here
/usr/include/opendht/logger.h:68:46: error: ‘format’ is not a constant expression
   68 |         logger(LogLevel::warning, fmt::format(format, args...));

same error on ubuntu 21.04 and 22.04

Solved wrapping the format string in fmt::runtime to disable compile-time checks

in logger.h file

changed this:

 template<typename S, typename... Args>
    inline void debug(S&& format, Args&&... args) const {
        logger(LogLevel::debug, fmt::format(format, args...));
    }
    template<typename S, typename... Args>
    inline void warn(S&& format, Args&&... args) const {
        logger(LogLevel::warning, fmt::format(format, args...));
    }
    template<typename S, typename... Args>
    inline void error(S&& format, Args&&... args) const {
        logger(LogLevel::error, fmt::format(format, args...));
    }

to this:

 template<typename S, typename... Args>
    inline void debug(S&& format, Args&&... args) const {
        logger(LogLevel::debug, fmt::format(fmt::runtime(format), args...));
    }
    template<typename S, typename... Args>
    inline void warn(S&& format, Args&&... args) const {
        logger(LogLevel::warning, fmt::format(fmt::runtime(format), args...));
    }
    template<typename S, typename... Args>
    inline void error(S&& format, Args&&... args) const {
        logger(LogLevel::error, fmt::format(fmt::runtime(format), args...));
    }

Don't now if this can cause problems, but now is compiling fine.

[aberaud]

Thanks for the report,
What version of {fmt} do you use ?
Thanks

[d3cod3]

fmt (GNU coreutils) 8.32

libfmt8 8.1.1+ds1-2
libfmt-dev 8.1.1+ds1-2

[ghenry]

Just got this testing on macOS on Sonoma. .configure didn't complain about no libfmnt:

In file included from ../include/opendht/dht.h:23:
../include/opendht/infohash.h:25:10: fatal error: 'fmt/core.h' file not found
   25 | #include <fmt/core.h>

I guess core.h is from a newer libfmt as doing brew install fmt sorted it:

brew install fmt
==> Downloading https://ghcr.io/v2/homebrew/core/fmt/manifests/11.1.0
################################################################################################################################# 100.0%
==> Fetching fmt
==> Downloading https://ghcr.io/v2/homebrew/core/fmt/blobs/sha256:43c8236da42ea4aaecd53306e72751f0d40d70c9e2b7a806cc184eab0549ba07
################################################################################################################################# 100.0%
==> Pouring fmt--11.1.0.arm64_sonoma.bottle.tar.gz
🍺  /opt/homebrew/Cellar/fmt/11.1.0: 29 files, 1MB
==> Running `brew cleanup fmt`..

Time to update the version check inconfigure.ac?

[ghenry]

I also get this after updating, so maybe a new issue to review configure.ac version checks in general?

../include/opendht/peer_discovery.h:28:10: fatal error: 'asio/steady_timer.hpp' file not found
   28 | #include <asio/steady_timer.hpp>

[ghenry]

I also get this after updating, so maybe a new issue to review configure.ac version checks in general?

../include/opendht/peer_discovery.h:28:10: fatal error: 'asio/steady_timer.hpp' file not found
   28 | #include <asio/steady_timer.hpp>

Which was fixed by:

==> Downloading https://ghcr.io/v2/homebrew/core/asio/manifests/1.30.2
################################################################################################################################# 100.0%
==> Fetching asio
==> Downloading https://ghcr.io/v2/homebrew/core/asio/blobs/sha256:8904055a14a4247b64b0b0109092dc16ec9b041a80b5575d41b19f4f68fa948d
################################################################################################################################# 100.0%
==> Pouring asio--1.30.2.arm64_sonoma.bottle.tar.gz
🍺  /opt/homebrew/Cellar/asio/1.30.2: 1,158 files, 39.2MB
==> Running `brew cleanup asio`.