Compiler error in socket.h on Amazon EC2 - c++

Question

I'm trying to compile bitcoin on my EC2 instance, and I've run into a problem I can't figure out. The build script stops on the following command
g++ -c -Wall -Wextra -Wformat -Wformat-security -Wno-unused-parameter -g -DMSG_NOSIGNAL=0 -DBOOST_SPIRIT_THREADSAFE -DUSE_UPNP=1 -DUSE_IPV6=1 -I/home/ec2-user/bitcoin/src/leveldb/include -I/home/ec2-user/bitcoin/src/leveldb/helpers -DHAVE_BUILD_INFO -I"/home/ec2-user/bitcoin/src" -I"/home/ec2-user/bitcoin/src/obj" -I"/usr/local/include" -I"/usr/include/openssl" -MMD -MF obj/alert.d -o obj/alert.o alert.cpp
by returning the following error(s)
In file included from /usr/include/sys/socket.h:40:0,
from compat.h:19,
from netbase.h:11,
from util.h:27,
from alert.h:13,
from alert.cpp:11:
/usr/include/bits/socket.h:231:5: error: expected identifier before numeric constant
/usr/include/bits/socket.h:231:5: error: expected ‘}’ before numeric constant
/usr/include/bits/socket.h:231:5: error: expected unqualified-id before numeric constant
In file included from compat.h:19:0,
from netbase.h:11,
from util.h:27,
from alert.h:13,
from alert.cpp:11:
/usr/include/sys/socket.h:254:1: error: expected declaration before ‘}’ token
I've tried compiling with the -std=c++0x option set, but it made no difference. That was the only thing I've been able to come up with.

Answer 1

I'd wager that some header file you have is #defineing a macro that interferes with socket.h. Are you able to compile a program that only includes <sys/socket.h>, with no other inclusions?
The next thing to check is to look at /usr/include/bits/socket.h and see what's on line 231 (where the first error occurs). If the code looks ok, then the next step is to see what the preprocessed source looks like. To get the preprocessed output, replace the -c option with -E on the command line, and change the -o obj/alert.o option to -o alert.ii to put the preprocessor output into the file alert.ii.
If you compare the content of alert.ii with /usr/include/bits/socket.h, you can see if it's getting compiled as expected or not. In particular, if there's a macro which defines something into something unexpected, you'll see code which is clearly wrong at the location the compiler is pointing out.