Why hasn't AddressSanitizer detected a memory leak in my program?

[ltimaginea]

My program is as follows:

#include <iostream>
#include <cassert>

class Singleton
{
public:
	static Singleton& Instance()
	{
		static Singleton& instance = *(new Singleton());
		return instance;	// potential leak
	}
public:
	Singleton(const Singleton&) = delete;
	Singleton(Singleton&&) = delete;
	Singleton& operator=(const Singleton&) = delete;
	Singleton& operator=(Singleton&&) = delete;
	~Singleton() = default;
private:
	Singleton() = default;
};

int main()
{
	auto& a = Singleton::Instance();
	auto& b = Singleton::Instance();
	assert(&a == &b);

	//delete (&Singleton::Instance());

	return 0;
}

Test environment: WSL2 Ubuntu 20.04.3 x86_64-linux-gnu-g++ 9.3.0

The method I use AddressSanitizer is as follows:

g++ -fsanitize=leak -g ./main.cpp
./a.out

or

g++ -fsanitize=address -g ./main.cpp
./a.out

The only delete expression delete (&Singleton::Instance()); has been commented out in my program. So my program should have a memory leak.

But, when I run the executable a.out , it outputs nothing.

Why hasn't AddressSanitizer detected a memory leak in my program?

[ramosian-glider]

The allocated memory is still reachable from a global variable (static Singleton& instance is a global), hence it is not considered a memory leak.
You can disable this behavior by passing LSAN_OPTIONS=use_globals=false:

$ g++ t.cc -o t -fsanitize=address
$ ./t
$ LSAN_OPTIONS=use_globals=false ./t

=================================================================
==3419665==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 73728 byte(s) in 1 object(s) allocated from:
    #0 0x7f5a9b0f4cd7 in malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:69
    #1 0x7f5a9acaf7ad  (/lib/x86_64-linux-gnu/libstdc++.so.6+0xaf7ad) (BuildId: 69568e25e14544c953a9f79da5e158d0f644ad17)

Direct leak of 1 byte(s) in 1 object(s) allocated from:
    #0 0x7f5a9b0f57f8 in operator new(unsigned long) ../../../../src/libsanitizer/asan/asan_new_delete.cpp:95
    #1 0x5595797f32ad in Singleton::Instance() (/usr/local/google/src/TMP/linux/t+0x12ad) (BuildId: 2e9033784f7ac303257f0b2ef41da0de10472db6)
    #2 0x5595797f31e5 in main (/usr/local/google/src/TMP/linux/t+0x11e5) (BuildId: 2e9033784f7ac303257f0b2ef41da0de10472db6)
    #3 0x7f5a9aa40c89 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58

SUMMARY: AddressSanitizer: 73729 byte(s) leaked in 2 allocation(s).