Hi Vicente, your commit New Revision: 76951 URL: http://svn.boost.org/trac/boost/changeset/76951 Thread: Added explicit to operator bool for locks (11 hours ago) leads to the following errors when using gcc-4.6.1 in non-c++11 mode: $BOOST_ROOT/boost/thread/locks.hpp:1323:34: warning: explicit conversion operators only available with -std=c++0x or -std=gnu++0x [enabled by default] It seems that the guards checking for explicit conversion operators are wrong. -#ifndef BOOST_NO_EXPLICIT_CONVERSION_OPERATORS +#if defined(BOOST_NO_EXPLICIT_CONVERSION_OPERATORS) Patch attached. Ok to commit? Yours, Jürgen -- Dipl.-Math. Jürgen Hunold | IVE mbH Software-Entwickler | Lützerodestraße 10 Tel: +49 511 897668 33 | 30161 Hannover, Germany Fax: +49 511 897668 29 | http://www.ivembh.de juergen.hunold@ivembh.de | | Geschäftsführer: Sitz des Unternehmens: Hannover | Univ.-Prof. Dr.-Ing. Thomas Siefer Amtsgericht Hannover, HRB 56965 | PD Dr.-Ing. Alfons Radtke