Allow linking examples to shared (rather than static) boost libraries with scons

[unphased]

I will try to debug the scons run soon, but here is where I'm at so far.

$ BOOST_INCLUDES=/usr/include  BOOST_LIBS=/usr/lib64 scons
scons: Reading SConscript files ...
C++11 build environment partially enabled
scons: done reading SConscript files.
scons: Building targets ...
g++ -o build/release/broadcast_server/broadcast_server.o -c -std=c++0x -O1 -fomit-frame-pointer -Wall -Wcast-align -Wshadow -Wunused-parameter -isystem /usr/include -DNDEBUG -D_WEBSOCKETPP_CPP11_STL_ -I. examples/broadcast_server/broadcast_
server.cpp
scons: *** [build/release/broadcast_server/broadcast_server] Implicit dependency `/usr/lib64/libboost_system.a' not found, needed by target `build/release/broadcast_server/broadcast_server'.
scons: building terminated because of errors.

$ sudo find / -name '*libboost_system*'
/usr/lib64/libboost_system-mt.so.1.53.0
/usr/lib64/libboost_system.so.1.53.0
/usr/lib64/libboost_system-mt.so
/usr/lib64/libboost_system.so

Environment is a Centos 7 with boost 1.53 (ugh, so old) and scons from packages.

I have zero experience with Scons. More than I have cmake. But since I hate cmake so much, it would be neat if we could get the scons build working.

[zaphoyd]

Specifically.. The scons build doesn't work when only shared (i.e. no static) boost libraries are present? A quick poke through the scons documentation indicates that it should work with shared libraries. Strange.

[unphased]

No idea. The thing I'm scratching my head about the most now is actually that if you open the massive manpage for scons, and search for the string "verbose", it is not found.

Anyway... seems like scons has its own ideas about fetching libraries (which I really question because isn't the gcc driver usually what we delegate that job to?)

$ BOOST_INCLUDES=/usr/include  BOOST_LIBS=/usr/lib64 scons --debug=findlibs                                                                                                                    
scons: Reading SConscript files ...
C++11 build environment partially enabled
scons: done reading SConscript files.
scons: Building targets ...
  findlibs: looking for 'libpthread.a' in '/usr/lib' ...
  findlibs: looking for 'libpthread.a' in '/usr/local/lib' ...
  findlibs: looking for 'libpthread.a' in '/usr/lib64' ...
  findlibs: looking for 'libpthread.so' in '/usr/lib' ...
  findlibs: looking for 'libpthread.so' in '/usr/local/lib' ...
  findlibs: looking for 'libpthread.so' in '/usr/lib64' ...
  findlibs: ... FOUND 'libpthread.so' in '/usr/lib64'
  findlibs: looking for 'librt.a' in '/usr/lib' ...
  findlibs: looking for 'librt.a' in '/usr/local/lib' ...
  findlibs: looking for 'librt.a' in '/usr/lib64' ...
  findlibs: looking for 'librt.so' in '/usr/lib' ...
  findlibs: looking for 'librt.so' in '/usr/local/lib' ...
  findlibs: looking for 'librt.so' in '/usr/lib64' ...
  findlibs: ... FOUND 'librt.so' in '/usr/lib64'
scons: *** [build/release/broadcast_server/broadcast_server] Implicit dependency `/usr/lib64/libboost_system.a' not found, needed by target `build/release/broadcast_server/broadcast_server'.
scons: building terminated because of errors.

[unphased]

I did an ill-advised sudo ln -s /usr/lib64/libboost_system.so /usr/lib64/libboost_system.a and the scons build is proceeding now.

Maybe the scons config scripts are funky?

[zaphoyd]

Ah. Line 42 of the SConstruct file says

boost_linkshared = False

Which indicates whether or not to link the boost libraries as static or shared. The default appears to be static. Changing this to true in your case should fix.

There should be a better way to specify this via the env rather than editing the SConstruct file though.

[unphased]

Well... I didnt really do anything out of the ordinary in setting up my environment, i strive for pristine VM installs... is boost ordinarily supposed to provide static libraries?

[zaphoyd]

A manual compile and the default package installs for every OS i've worked with includes both static and shared libraries.

[unphased]

Hmm, I see... well. Can we just allow it to use the shared libs? It should work, right?

[unphased]

changing line 42 to set to True results in

scons: *** [build/release/broadcast_server/broadcast_server] Implicit dependency `/usr/lib64/$LIBPREFIXboost_system.so' not found, needed by target `build/release/broadcast_server/broadcast_server'.
scons: building terminated because of errors.

[unphased]

Maybe I will just do a boost install from source and be rid of this headache. Besides, 1.53 is like ancient.

[zaphoyd]

WebSocket++ examples absolutely work fine with the boost libraries linked shared, assuming we can get the build script to name things correctly =)

It looks like setting it to true picks up the right extension/suffix, but not the right library prefix. hmm

[zaphoyd]

can you try defining SHLIBPREFIX to lib?