It had been revealed that there have been backdoor implanted in OpenBSD http://www.infoworld.com/d/developer-world/software-security-honesty-the-best-policy-285

OpenBSD is opensource, how is it that nobody in the community developper could see it in the source code ?

So how can one trust all the other "opensource" Linux

Of course OpenBSD is only a case, the point is not about OpenBSD, it is about opensource in general.

my question is not about Openbsd per se it's about source code os inspection especially c/c++ since most are written in these languages.

Also once the source is compiled how one can be sure that it really reflects the source code ?

If a law requires that a backdoor being implanted and obliges to deny that kind of action under the guise of security, how can you be sure that the system has not been corrupted by some tools ?

As said there is there is a "nondisclosure agreement"

My guess is that 99.99% of developpers in the world are just incapable of understanding os source code and won't even bother to look at it.

And above all nobody wonders about why the gov wants such massive backdoor, and that of course they will pressure medias to deny.