I ran across the error Socket operation on non-socket in some of my networking code when calling connect and spent a lot of time trying to figure out what was causing it. I finally figured out that the following line of code was causing the problem:

if ((sockfd = socket( ai->ai_family, ai->ai_socktype, ai->ai_protocol) < 0)) {

See the problem? Here's what the line should look like:

if ((sockfd = socket( ai->ai_family, ai->ai_socktype, ai->ai_protocol)) < 0) {

What I don't understand is why the first, incorrect line doesn't produce a warning. To put it another way, shouldn't the general form:

if ( foo = bar() < baz ) do_something();

look odd to the compiler, especially running with g++ -Wall -Wextra?

If not, shouldn't it at least show up as "bad style" to cppcheck, which I'm also running as part of my compile?