GCC: static data member optimized out in the debug build

Consider the following simple code:

template<typename T>
struct Base {
    static constexpr int v = 0;
};

struct Derived : Base<int> {};

int main() {
    Derived d;
}

I compile it with GCC (8.3.0, 9.1.0, g++ -g -O0 test.cpp), then run GDB to examine the value of d:

(gdb) p d
$1 = {<Base<int>> = {static v = <optimized out>}, <No data fields>}

d.v is gone... I tried to use -ggdb, -ggdb3, -fvar-tracking with no success.

If I compile with clang (clang++ -g -O0 test.cpp), I see the expected result:

(gdb) p d
$1 = {<Base<int>> = {static v = 0}, <No data fields>}

This output is also seen with GCC if Base is not a template class:

(gdb) p d
$1 = {<Base> = {static v = 0}, <No data fields>}

Where did d.v go? Why was it optimized out? Is it possible to prevent this optimization without modifying the source code?