我有一个带有静态变量（'abc.cpp'）的精简简单程序：
#include <iostream>
int main(int, char**)
{
static const std::string a("123");
std::cout << "Hello world" << std::endl;
return 0;
}
我编译它并且它有效：
> g++ -ggdb abc.cpp -o abc
> ./abc
Hello world
但是，如果我链接到 pthread 库......
> g++ -ggdb -lpthread abc.cpp -o abc
> ./abc
Segmentation fault (core dumped)
> gdb abc
(gdb) run
Starting program: abc
Program received signal SIGSEGV, Segmentation fault.
0x0000000000000000 in ?? ()
(gdb) where
#0 0x0000000000000000 in ?? ()
#1 0x00007ffff7b01681 in ?? () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#2 0x00007ffff7b016c3 in std::locale::locale() () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#3 0x00007ffff7afe244 in std::ios_base::Init::Init() ()
from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#4 0x0000000000400d03 in __static_initialization_and_destruction_0 (__initialize_p=1,
__priority=65535) at /usr/include/c++/4.9/iostream:74
#5 0x0000000000400d2c in _GLOBAL__sub_I_main () at abc.cpp:8
#6 0x0000000000400d7d in __libc_csu_init ()
#7 0x00007ffff74a6e55 in __libc_start_main (main=0x400c06 <main(int, char**)>, argc=1,
argv=0x7fffffffdb58, init=0x400d30 <__libc_csu_init>, fini=<optimised out>,
rtld_fini=<optimised out>, stack_end=0x7fffffffdb48) at libc-start.c:246
#8 0x0000000000400b39 in _start ()
我知道它在这里不使用线程，但在实际的非精简程序中，它链接到一个使用线程的库。感觉即使实际上没有使用线程，链接到 pthread 应该没问题。
有趣的是，添加消毒剂使其不会崩溃（不确定这是否是“未定义”/不稳定的修复......）。
> g++ -ggdb -fsanitize=undefined -lpthread abc.cpp -o abc
> ./abc
Hello world
为什么这会导致段错误？
旁注：Clang 有效。
> clang++ -ggdb -lpthread abc.cpp -o abc
> ./abc
Hello world
版本信息：
> g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.9/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.9.2-0ubuntu1~14.04' --with-bugurl=file:///usr/share/doc/gcc-4.9/README.Bugs --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.9 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.9 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.9-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.9.2 (Ubuntu 4.9.2-0ubuntu1~14.04)
> dpkg -l 'libstdc++6*'
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-===================-==============-==============-===========================================
ii libstdc++6:amd64 5-20150329-1ub amd64 GNU Standard C++ Library v3
un libstdc++6-4.0-dbg <none> <none> (no description available)
un libstdc++6-4.1-dbg <none> <none> (no description available)
un libstdc++6-4.2-dbg <none> <none> (no description available)
un libstdc++6-4.3-dbg <none> <none> (no description available)
un libstdc++6-4.4-dbg <none> <none> (no description available)
un libstdc++6-4.5-dbg <none> <none> (no description available)
un libstdc++6-4.6-dbg <none> <none> (no description available)
un libstdc++6-4.7-dbg <none> <none> (no description available)
un libstdc++6-4.8-dbg <none> <none> (no description available)
ii libstdc++6-4.9-dbg: 4.9.2-0ubuntu1 amd64 GNU Standard C++ Library v3 (debugging file
un libstdc++6-5-dbg <none> <none> (no description available)
un libstdc++6-dbg <none> <none> (no description available)
这是ldd abc对于海湾合作委员会构建：
linux-vdso.so.1 => (0x00007ffef8f2f000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f87b167c000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f87b1465000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f87b109f000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f87b0d99000)
/lib64/ld-linux-x86-64.so.2 (0x00007f87b1a11000)
And the ldd abc对于 clang 构建（请注意此处的 pthread，而不是 gcc 中的）：
linux-vdso.so.1 => (0x00007fffa4cc7000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fab1f10d000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fab1ed94000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fab1ea8d000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fab1e876000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fab1e4b1000)
/lib64/ld-linux-x86-64.so.2 (0x00007fab1f347000)
就其价值而言，我的语言环境：
> locale
LANG=en_AU.UTF-8
LANGUAGE=en_AU:en
LC_CTYPE="en_AU.UTF-8"
LC_NUMERIC="en_AU.UTF-8"
LC_TIME="en_AU.UTF-8"
LC_COLLATE="en_AU.UTF-8"
LC_MONETARY="en_AU.UTF-8"
LC_MESSAGES="en_AU.UTF-8"
LC_PAPER="en_AU.UTF-8"
LC_NAME="en_AU.UTF-8"
LC_ADDRESS="en_AU.UTF-8"
LC_TELEPHONE="en_AU.UTF-8"
LC_MEASUREMENT="en_AU.UTF-8"
LC_IDENTIFICATION="en_AU.UTF-8"
LC_ALL=
设置默认区域设置会产生相同的结果（以及相同的堆栈跟踪）：
> LC_ALL=C ./abc
Segmentation fault (core dumped)
