c++ linker error and undefined reference when accessing static constexpr member – Ubuntu

#include <stddef.h>
#include <array>

struct S {
    static constexpr std::array<int,5> sca = {1,2,3,4,5};

    static constexpr int foo(size_t i) {
        return sca[i];
    }
};

int main(int argc, char **argv) {
    S s;
    return s.foo(4);
}

Compiling this gives me a linker error and an undefined reference:

$ g++ --std=c++14 -O0 -o test1 test1.cpp 
/usr/bin/ld: /tmp/ccfZJHBY.o: warning: relocation against `_ZN1S3scaE' in read-only section `.text._ZN1S3fooEm[_ZN1S3fooEm]'
/usr/bin/ld: /tmp/ccfZJHBY.o: in function `S::foo(unsigned long)':
test1.cpp:(.text._ZN1S3fooEm[_ZN1S3fooEm]+0x1a): undefined reference to `S::sca'
/usr/bin/ld: warning: creating DT_TEXTREL in a PIE
collect2: error: ld returned 1 exit status

I checked my g++ version it turned out to be 11.3:

$ g++ --version
g++ (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0
...

The strangest thing is: this code compiles fine in CompilerExplorer with x86-64 gcc 11.3: https://godbolt.org/z/rjG31z9hY

So I thought that maybe it is a compiler version issue, but compiling with g++-12 yielded the same result:

$ /usr/bin/g++-12 --std=c++14 -O0 -o test1 test1.cpp
/usr/bin/ld: /tmp/ccH1PFkh.o: warning: relocation against `_ZN1S3scaE' in read-only section `.text._ZN1S3fooEm[_ZN1S3fooEm]'
/usr/bin/ld: /tmp/ccH1PFkh.o: in function `S::foo(unsigned long)':
test1.cpp:(.text._ZN1S3fooEm[_ZN1S3fooEm]+0x1a): undefined reference to `S::sca'
/usr/bin/ld: warning: creating DT_TEXTREL in a PIE
collect2: error: ld returned 1 exit status

$ /usr/bin/g++-12 --version
g++-12 (Ubuntu 12.1.0-2ubuntu1~22.04) 12.1.0
...

I found out that it works with --std=c++17 and with -O1:

$ g++ --std=c++14 -O1 -o test1 test1.cpp 
$ ./test1 
$ echo $?
5

$ g++ --std=c++17 -O0 -o test1 test1.cpp 
$ ./test1 
$ echo $?
5

I have also found out that binding the result of foo to a variable on the stack somehow fixes the issue:

int main(int argc, char **argv) {
    S s;
    constexpr int x = s.foo(4);
    return x;
}

And allows this code to be built and executed without changing compilation flags:

$ g++ --std=c++14 -O0 -o test2 test2.cpp 
$ ./test2 
$ echo $?
5

Why does it behave like that?