const variables in header file and static initialization fiasco

Question

After reading a lot of the questions regarding initialization of static variables I am still not sure how this applies to const variables at namespace level.

I have kind of the following code in a header file config.h generated by the build script:

static const std::string path1 = "/xyz/abc";
static const std::string path2 = "/etc";

According to what I have read the static keyword is not necessary, even deprecated here.

My Question: Is the code above prone to the static initialization fiasco?

If I have the following in a header file myclass.h:

class MyClass
{
public:
    MyClass(const std::string& str) : m_str(str) {}
    std::string Get() const { return m_str; }

private:
    std::string m_str;
}

const MyClass myclass1("test");

Will this pose any problems with static initialization?

If I understood right, due to const variables having internal linkage there should be no problem in both cases?

Edit: (due to dribeas answer)

Maybe I should mention that I am interested in use cases like:

In main.cpp:

#include <config.h>
#include <myclass.h>

std::string anotherString(path1 + myclass1.Get());

int main()
{
    ...
}

Another question regarding this use case: Will the compiler optimize away path2 in this case?

Answer 1

I tried to get the necessary information right from the C++03 Standard document. Here is what I found:

Regarding the const static declarations:

According to section 3.5.3 objects defined at namespace level and declared const have internal linkage by default. static also declares a namespace level object to have internal linkage so there is no need to declare an object static const.

Also according to Annex D.2

The use of the static keyword is deprecated when declaring objects in namespace scope (see 3.3.5).

Regarding the static initialization fiasco:

Since the variables are defined in a header file they are always defined before any other static objects using them.

From section 3.6.2.1:

Objects with static storage duration defined in namespace scope in the same translation unit and dynamically initialized shall be initialized in the order in which their definition appears in the translation unit.

Answer 1: This means passing the variables to a static object constuctor should be fine.

Answer 2: However a problem could occur if the variables are referenced from a non-inline constructor of a static object:

Neither in section 3.6.2.1 nor 3.6.2.3 is it specified in which order the static objects in different compilation units are initialized if dynamic initialization is done before the first statement of main.

Consider the following:

// consts.h
#include <string>

const std::string string1 = "ham";
const std::string string2 = "cheese";

// myclass.h
#include <string>

class MyClass
{
public:
    MyClass();
    MyClass(std::string str);
    std::string Get() { return memberString; }
private:
    std::string memberString;
}

// myclass.cpp
#include "consts.h"
#include "myclass.h"

MyClass::MyClass() : memberString(string1) {}

MyClass::MyClass(std::string str) : memberString(str) {}

// main.cpp
#include <iostream>
#include "consts.h"
#include "myclass.h"

MyClass myObject1;
MyClass myObject2(string2);

using namespace std;

int main()
{
    cout << myObject1.Get(); // might not print "ham"
    cout << myObject2.Get(); // will always print "cheese"
}

Since myclass.cpp has its own copy of the const variables, these might not be initialized when MyClass::MyClass() is called.

So yes, const variables defined in header files can be used in a way that is prone to the static initialization fiasco

As far as I can see this does only apply to variables not requiring static initialization:

From C++03 standard, section 3.6.2.1:

Objects of POD types (3.9) with static storage duration initialized with constant expressions (5.19) shall be initialized before any dynamic initialization takes place.