[C/C++] __attribute__((constructor)) and variable initialization in C++.

Let me share quite interesting observation.

Environment

• clang++: aarch64-linux-android34-clang++ of android NDK.
• Run on android device

Think about following project

a.cpp

namespace {
    std::map<std::string, int> m0_;
}
static std::map<std::string, int> m1_;

void noticeFromConstructor(const char *name, int value) {
    static std::map<std::string, int> m2_;
    m0_[name]  = value; // (*1)
    m1_[name]  = value; // (*2)
    m2_[name]  = value; // (*3)
}

b.cpp

namespace {
__attribute__((constructor)) void notify() {
    noticeFromConstructor("b", 1);
}

c.cpp

__attribute__((constructor)) static void notify() {
    noticeFromConstructor("c", 2);
}

SIGSEGV is signalled at both (1) and (2) when it run - from both b.cpp and c.cpp - but, (*3) is ok. I think it's because m0_ and m1_ are not initialized yet, but m2_ is initialized.
I'm not sure that there is any explicit description regarding initialization order for this case.