codeql/cpp/ql/test/query-tests/Best Practices/Unused Entities/UnusedLocals/code2.cpp

int test_const_init()
{
	int v1; // BAD: unused
	int v2; // GOOD
	int v3 = 0; // BAD: unused
	int v4 = 0; // GOOD
	const int v5 = 0; // BAD: unused [NOT DETECTED]
	const int v6 = 0; // GOOD
	constexpr int v7 = 0; // BAD: unused
	constexpr int v8 = 0; // GOOD
	
	return v2 + v4 + v6 + v8;
}

// ---

template<int i>
void myFunction()
{
}

void test_template_parameter()
{
	constexpr int v1 = 0; // BAD: unused
	constexpr int v2 = 0; // GOOD: used as a template parameter below [FALSE POSITIVE]

	myFunction<v2>();
}

// ---

class MyBuffer
{
public:
	unsigned char buffer[40];
};

void test_unused()
{
	MyBuffer myVar1; // BAD: unused
	MyBuffer myVar2; // GOOD: used in deliberate void cast below
	MyBuffer myVar3 __attribute((__unused__)); // GOOD: unused but acknowledged
	
	(void)myVar2;
}

// ---

#define likely(x) __builtin_expect ((x), 1)
#define unlikely(x) __builtin_expect ((x), 0)

static int getter() {}

void test_expect()
{
	int i;

	for (i = 0; i < 100000; i++)
	{
		int v1 = getter(); // GOOD: v1 is used
		int v2 = getter(); // GOOD: v2 is used
		int v3 = getter(); // BAD: unused

		if (unlikely(v1 < 0))
		{
			int a = i;
			int b = a;
			a += b;
			b = -1;
			break;
		}
		if (__builtin_expect(v2, 0))
		{
			break;
		}
	}
}