Example use of __cxa_demangle with no memory leaks

__cxa_demangle_example.cpp

// Original example from https://gcc.gnu.org/onlinedocs/libstdc++/manual/ext_demangling.html

#include <cmath>
#include <cstdlib>
#include <array>
#include <exception>
#include <iostream>
#include <sstream>
#include <stdexcept>
#include <cxxabi.h>

struct empty {
};

template<typename T, int N>
struct foobar {
};

std::array<char const*, 4> lookup =
{{
	"The demangling operation succeeded",
	"A memory allocation failure occurred",
	"mangled_name is not a valid name under the C++ ABI mangling rules",
	"One of the arguments is invalid"
}};

int main()
{
	std::size_t sz = 17;
	char* buffer = static_cast<char*>(std::malloc(sz));

	// exception classes not in <stdexcept>, thrown by the implementation
	// instead of the user
	int status;
	std::bad_exception x;
	std::exception & e = x;
	char *realname = abi::__cxa_demangle(e.what(), buffer, &sz, &status);
	if (realname) {
		std::cout << e.what() << "\t=> `" << realname << "'\t: " << status
		                << '\n';
		buffer = realname;
	} else {
		std::cout << "demangle for `" << e.what() << "' failed due to `"
		                << lookup[std::abs(status)] << "'\n";
	}

	// typeid
	foobar<empty, 17> u;
	const std::type_info &ti = typeid(u);

	realname = abi::__cxa_demangle(ti.name(), buffer, &sz, &status);
	if (realname) {
		std::cout << ti.name() << "\t=> `" << realname << "'\t: " << status
		                << '\n';
		buffer = realname;
	} else {
		std::cout << "demangle for `" << ti.name()
		                << "' failed due to `"
		                << lookup[std::abs(status)] << "'\n";
	}

	std::free(buffer);

	return 0;
}

std::unique_ptr<char, decltype(free)*> demangle_name(abi::__cxa_demangle(name.c_str(), 0, 0, &status), free);
if(!demangle_name)
...

https://godbolt.org/z/h6YK91d54

also completely different approach: https://stackoverflow.com/a/56766138