[Boost-build] Suppress "weak external" exports from Mac OS X executables?

Subject: [Boost-build] Suppress "weak external" exports from Mac OS X executables?
From: Allen Cronce (allenslists_at_[hidden])
Date: 2008-11-24 21:51:06

Hi all,

We're using boost static libraries in our projects. We've noticed that  
there are tons of symbol exports in our Mac OS X executables, even  
after stripping. Here's an excerpt from an "nm -m" command:

--snip--
00008330 (__TEXT,__text) weak external  
__ZN5boost10filesystem10basic_pathISsNS0_11path_traitsEEdVEPKc
0000c240 (__TEXT,__text) weak external  
__ZN5boost10filesystem22basic_filesystem_errorINS0_10basic_pathISsNS0_11path_traitsEEEEC2ERKSsRKS4_NS_6system10error_codeE
00009d80 (__TEXT,__text) weak external  
__ZN5boost10filesystem22basic_filesystem_errorINS0_10basic_pathISsNS0_11path_traitsEEEED0Ev
00009ef0 (__TEXT,__text) weak external  
__ZN5boost10filesystem22basic_filesystem_errorINS0_10basic_pathISsNS0_11path_traitsEEEED1Ev
0000b340 (__TEXT,__text) weak external  
__ZN5boost15throw_exceptionINS_10filesystem22basic_filesystem_errorINS1_10basic_pathISsNS1_11path_traitsEEEEEEEvRKT_
00008540 (__TEXT,__text) weak external  
__ZN5boost16exception_detail10clone_baseD0Ev
--snip--

Note that these are "defined" externals, meaning the code being  
exported actually exists in the executable section of the binary. I  
would expect to possibly see exported symbols like this in shared  
libraries, but not application executables. In some applications, we  
see hundreds of these exports.

I've tried to suppress these symbols by disabling visibility in the  
boost static libraries, but that hasn't worked. Yes, I'm aware of gcc  
4.0 visibility issues with exception handling across shared libraries.  
But since we're statically linking, we shouldn't see those kind of  
problems.

I suspect that the problem is I'm just not passing the cflags or  
cxxflags correctly. Either that, or this isn't really a symbol  
visibility issue.

In any case, here's the command line I tried:

./tools/jam/src/bin.macosxx86/bjam debug release toolset=darwin  
address-model=32 architecture=combined threading=multi  
link=shared,static macosx-version=10.5 macosx-version-min=10.4 darwin/ 
cflags=-fvisibility=hidden darwin/cxxflags=-fvisibility=hidden -- 
layout=system --prefix=/tmp/boostbuild_20081124_142343/32 --exec- 
prefix=/tmp/boostbuild_20081124_142343/32 --builddir=../../../ 
buildProductsMac/boost install

Thanks in advance for any suggestions regarding eliminating these  
symbol exports.

Best,
--
Allen Cronce