C++ static initializers in C programs

a.cpp

extern "C" int foo;

bool init() {
  foo = 42;
}
static bool inited = init();

b.c

#include <stdio.h>

int foo;

int main() {
  printf("%d\n", foo);
  return 0;
}

output

gcc -c b.c
g++ -c a.cpp
gcc -v a.o b.o -lstdc++ -o e
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: /build/gcc-multilib/src/gcc-4.8-20140206/configure --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/ --enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++ --enable-shared --enable-threads=posix --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch --disable-libssp --enable-gnu-unique-object --enable-linker-build-id --enable-cloog-backend=isl --disable-cloog-version-check --enable-lto --enable-plugin --enable-install-libiberty --with-linker-hash-style=gnu --enable-multilib --disable-werror --enable-checking=release
Thread model: posix
gcc version 4.8.2 20140206 (prerelease) (GCC) 
COMPILER_PATH=/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/:/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/:/usr/lib/gcc/x86_64-unknown-linux-gnu/:/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/:/usr/lib/gcc/x86_64-unknown-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/:/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../lib/:/lib/../lib/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-o' 'e' '-mtune=generic' '-march=x86-64'
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/collect2 --build-id --eh-frame-hdr --hash-style=gnu -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o e /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../lib/crt1.o /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../lib/crti.o /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/crtbegin.o -L/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2 -L/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../lib -L/lib/../lib -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../.. a.o b.o -lstdc++ -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/crtend.o /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../lib/crtn.o
./e
42
gcc -v a.o b.o -lstdc++ -o e.static -static
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: /build/gcc-multilib/src/gcc-4.8-20140206/configure --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/ --enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++ --enable-shared --enable-threads=posix --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch --disable-libssp --enable-gnu-unique-object --enable-linker-build-id --enable-cloog-backend=isl --disable-cloog-version-check --enable-lto --enable-plugin --enable-install-libiberty --with-linker-hash-style=gnu --enable-multilib --disable-werror --enable-checking=release
Thread model: posix
gcc version 4.8.2 20140206 (prerelease) (GCC) 
COMPILER_PATH=/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/:/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/:/usr/lib/gcc/x86_64-unknown-linux-gnu/:/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/:/usr/lib/gcc/x86_64-unknown-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/:/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../lib/:/lib/../lib/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-o' 'e.static' '-static' '-mtune=generic' '-march=x86-64'
 /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/collect2 --build-id --hash-style=gnu -m elf_x86_64 -static -o e.static /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../lib/crt1.o /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../lib/crti.o /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/crtbeginT.o -L/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2 -L/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../lib -L/lib/../lib -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../.. a.o b.o -lstdc++ --start-group -lgcc -lgcc_eh -lc --end-group /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/crtend.o /usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/../../../../lib/crtn.o
./e.static
42

run

#!/bin/sh

set -e
set -v

gcc -c b.c
g++ -c a.cpp
gcc -v a.o b.o -lstdc++ -o e
./e
gcc -v a.o b.o -lstdc++ -o e.static -static
./e.static