Re: "might be used uninitialized..." what?

It's possible that I'm blind on both eyes.

After all, it's late in the day (or morning) for me.

But, I have this code which adds a string to a list of strings:

    virtual cppx::Index add(
        cppx::WideString const& s, cppx::WideString const& data
        )
    {
        int const id = myStrings.add( data );

        try
        {
            return Base::basicAdd( s, id );
        }
        catch( ... )
        {
            myStrings.remove( id );
            throw;
        }
    }

Compiling with g++ 3.4.5, options (copy/paste from the IDE's build log)

  -Wall -O -pedantic -Wall -g -O -pedantic -Wall -std=c++98
-Wno-long-long -Wwrite-strings

the compiler complains that

    warning: 'id' might be used uninitialized in this function

What is it that the compiler sees that I don't see?