Whether in C or C++, I think that this illegal program, whose behavior according

Question

Whether in C or C++, I think that this illegal program, whose behavior according to the C or C++ standard is undefined, is interesting:

#include <stdio.h>

int foo() {
    int a;
    const int b = a;
    a = 555;
    return b;
}

void bar() {
    int x = 123;
    int y = 456;
}

int main() {
    bar();
    const int n1 = foo();
    const int n2 = foo();
    const int n3 = foo();
    printf("%d %d %d ", n1, n2, n3);
    return 0;
}
Output on my machine (after compilation without optimization):

123 555 555
I think that this illegal program is interesting because it illustrates stack mechanics, because the very reason one uses C or C++ (instead of, say, Java) is to program close to the hardware, close to stack mechanics and the like.

However, on StackOverflow, when a questioner's code inadvertently reads from uninitialized storage, the most heavily upvoted answers invariably quote the C or C++ (especially C++) standard to the effect that the behavior is undefined. This is true, of course, as far as the standard goes

Explanation / Answer

Frama-C's value analysis, a static analyzer the purported goal of which is to find all undefined behaviors in a C program, considers the assignment const int b = a; as okay. This is a deliberate design decision in order to allow memcpy() (typically implemented as a loop over unsigned char elements of a virtual array, and that the C standard arguably allows to re-implement as such) to copy a struct (which can have padding and uninitialized members) to another.

The

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