codeql/cpp/ql/test/query-tests/Best Practices/Unused Entities/UnusedStaticVariables/test.cpp

int globalVar; // GOOD (not static)
static int staticVar1; // GOOD (used)
static int staticVar2; // GOOD (used)
static int staticVar3 = 3; // GOOD (used)
static int staticVar4 = staticVar3; // GOOD (used)
static int staticVar5; // BAD (unused)
static int staticVar6 = 6; // BAD (unused)
static __attribute__((__unused__)) int staticVar7; // GOOD (unused but this is expected)
const int constVar8 = 8; // BAD (const defaults to static)
extern const int constVar9 = 9; // GOOD
static int staticVar10 = 10; // GOOD [FALSE POSITIVE] (referenced in a never instantiated template)

void f()
{
	int *ptr = &staticVar4;

	staticVar1 = staticVar2;
	(*ptr) = 0;
}

template<class T>
class MyTemplateClass // never instantiated
{
public:
	MyTemplateClass(int param = staticVar10)
	{
		// ...
	}
};