How to suppress "warning: missing initializer" caused by Boost.Log and GCC 4.4?

Question

Can anyone tell me how to suppress the following warning message which is generated by Boost.Log and GCC 4.4.7? My project is built in C++11 mode (with -std=c++0x in GCC 4.4.7).

src/Logger.cc:7: warning: missing initializer for member ‘boost::log::v2_mt_posix::expressions::attribute_keyword<tag::severity, boost::phoenix::actor>::proto_expr_’

where src/Logger.cc is the source file of my logging class which is a wrapper of Boost.Log. Line 7 uses one of Boost.Log macros as follows. Logger::ESeverityLevel is an enum defined in Logger.h.

BOOST_LOG_ATTRIBUTE_KEYWORD(severity, "Severity", Logger::ESeverityLevel)

This macro can be expanded as follows.

namespace tag    {\
        struct severity :\
            public ::boost::log::expressions::keyword_descriptor\
        {\
            typedef Logger::ESeverityLevel value_type;\
            static ::boost::log::attribute_name get_name() { return ::boost::log::attribute_name("Severity"); }\
        };\
    }\
    typedef ::boost::log::expressions::attribute_keyword< tag::severity > severity_type;    const severity_type severity = {};

It looks that the initialization of severity_type makes this warning, while it is valid with Clang (Apple LLVM version 6.0).

An official example code of this macro can be found at http://theboostcpplibraries.com/boost.log#ex.log_05

Answer 1

One approach is to disable the warning in GCC using it's built-in #pragmas, e.g.

#pragma GCC diagnostic push      // Save the current warning state
#pragma GCC diagnostic ignored "-Wmissing-field-initializers" // Disable the warning you're getting

...
// offending code
BOOST_LOG_ATTRIBUTE_KEYWORD(severity, "Severity", Logger::ESeverityLevel)
...

#pragma GCC diagnostic pop        // Restore previous default behaviour

You can also disable this behaviour at the command line using the -Wno-missing-field-initializers.