Re: [Boost-users] [OSX] Multiply defined symbols between Function and Signals libs ?

From: Alo Sarv (alo17_at_[hidden])
Date: 2004-11-29 15:38:15

Peter Dimov wrote:

> Alo Sarv wrote:
>
>> I'v been compiling boost libraries objects straight into my
>> application binaries on linux and OSX platforms (e.g. not using
>> bjam/stat/dynlibs), and thus far it has worked. However, recently I
>> started getting multiply defined symbols on OSX, namely _1, _2, _3
>> etc. Most likely they come between Boost.Function and Boost.Signals
>> libraries (latter of which I started using recently).
>
>
> _1, _2 and so on can come from either Boost.Bind or Boost.Lambda. If 
> you are using Boost.Bind, these are defined in 
> <boost/bind/placeholders.hpp>. Take a look at this file, and you'll 
> see three different compiler-specific paths, of which you are probably 
> using the last (g++ on OSX, right?)
>
> Since the placeholders are defined in an unnamed namespace, there 
> shouldn't be any multiple definition errors, so it's probably a 
> compiler bug. Check whether you have two source files with the same 
> name, as this may be the cause. Otherwise, as a last resort, you may 
> try editing placeholders.hpp so that one of the other #ifdef sections 
> is selected.

Well, I currently resolved the problem by rearranging some #includes in 
my headers. However, the real fix is described here:
http://developer.apple.com/technotes/tn2002/tn2071.html#Section7
So the real fix would be to use -multiply-defined supress compiler flag. 
So, not a compiler bug, a compiler feature :)

Alo Sarv.