id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,phab_field
2469,[PATCH] link failure without not-used Boost.Signals library when Boost.Signals2 is used,fabio,,"Since r13716 with Boost >= 1.54 Boost.Signal2 is used rather than Boost.Signal. However it still try to link to Boost.Signal and, if this is not available, linking fails:

{{{
/usr/bin/ld: impossibile trovare -lboost_signals
collect2: error: ld returned 1 exit status
make[1]: *** [../../../binaries/system/libAtlasUI.so] Errore 1
make: *** [AtlasUI] Errore 2
}}}

So r13716 is not enough to work with a (future) version without signals1, it will compile OK, but will fail at linking.

Possible solutions:
* change the check to use signals2 from 1.54 and use 1.40 ([http://www.boost.org/doc/libs/1_55_0/doc/html/signals2/api_changes.html updated version with signals2], [http://www.boost.org/users/history/version_1_40_0.html released in 2009]), and remove all the signal link flags from extern_libs4.lua (there is no need to add other libs to link, since signals2 is apparently in main boost lib now). This way we'll drop support for older boost version (it should not be a problem, every supported Ubuntu version (up to lucid/10.04) has at least 1.40, while precise/12.04 (older version with 0ad packages in the PPA) has 1.48);
* just modify extern_libs4.lua to not use the signals link flags whit boost >= 1.54.

I prefer the first approach, it's simpler (remove some code from extern_libs4.lua) and not dependent on the Boost version. The attached patch does this.",defect,new,Must Have,Alpha 17,Build & Packages,,review patch,,