What -W values in gcc correspond to which actual warnings?

Question

Preamble: I know, disabling warnings is not a good idea. Anyway, I have a technical question about this.

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Using GCC 3.3.6, I get the following warning:

choosing ... over ... because conversion sequence for the argument is better.

Now, I want to disable this warning as described in gcc warning options by providing an argument like

-Wno-theNameOfTheWarning

But I don't know the name of the warning. How can I find out the name of the option that disables this warning?

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I am not able to fix the warning, because it occurs in a header of an external library that can not be changed. It is in boost serialization (rx(s, count)):

template<class Archive, class Container, class InputFunction, class R>
inline void load_collection(Archive & ar, Container &s)
{
    s.clear();
    // retrieve number of elements
    collection_size_type count;
    unsigned int item_version;
    ar >> BOOST_SERIALIZATION_NVP(count);
    if(3 < ar.get_library_version())
        ar >> BOOST_SERIALIZATION_NVP(item_version);
    else
        item_version = 0;
    R rx;
    rx(s, count);
    std::size_t c = count;
    InputFunction ifunc;
    while(c-- > 0){
        ifunc(ar, s, item_version);
    }
}

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I have already tried #pragma GCC system_header but this had no effect. Using -isystem instead of -I also does not work.

The general question remains is: I know the text of the warning message. But I do not know the correlation to the gcc warning options.

Answer 1

How about change your code to remove the warning? It sounds like you probably should cast one of your parameters to a specific type instead of having the compiler choose which cast to do.

Answer 2

Two points: You should leave warnings on - compiler warnings bode ill later on - crashes, corruption, etc.

The used to be the -Wnotanidiot flag. This was around in late version 2.9 ... 3.o of gcc. I don't know if it still works, but this warning would qualify.

Answer 3

You can find out what option is associated with a given warning by using the -fdiagnostics-show-option option:

$ gcc -fdiagnostics-show-option -Wall foo.c
foo.c: In function ‘main’:
foo.c:3: warning: suggest parentheses around assignment used as truth value [-Wparentheses]

And my two cents about this: assuming there's no way to actually fix the warning, hopefully you can manage to disable the warning for a minimal amount of compilation, so that if you make a similar mistake in your own code, you'll be warned.

Edit: This appears to be -Wconversion. (Found by poking in the source - you can just grep for some of the warning text, and find the call to warning( OPT_W_conversion, ....)

Answer 4

The answer to the question, "How can I find out the name of the option that disables this warning?" is "Read the source of the compiler."