Release heap memory when it goes out of scope in C

a.c

// gcc a.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void clean_name(char **name) {
    printf("clean clean!");
    free(*name);
}

void show(char *name) {
    printf("hello %s\n", name);
}

void action() {
    char *name __attribute__((cleanup (clean_name))) = malloc(sizeof(char) * 20);
    strcpy(name, "test test");
    show(name);
}

int main() {
    action();
}

after

valgrind --tool=memcheck ./a.out
==575637== Memcheck, a memory error detector
==575637== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al.
==575637== Using Valgrind-3.22.0 and LibVEX; rerun with -h for copyright info
==575637== Command: ./a.out
==575637==
hello mort
clean clean!==575637==
==575637== HEAP SUMMARY:
==575637==     in use at exit: 0 bytes in 0 blocks
==575637==   total heap usage: 2 allocs, 2 frees, 1,044 bytes allocated
==575637==
==575637== All heap blocks were freed -- no leaks are possible
==575637==
==575637== For lists of detected and suppressed errors, rerun with: -s
==575637== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

before

valgrind --tool=memcheck ./a.out
==574035== Memcheck, a memory error detector
==574035== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al.
==574035== Using Valgrind-3.22.0 and LibVEX; rerun with -h for copyright info
==574035== Command: ./a.out
==574035==
hello mort
clean clean!==574035==
==574035== HEAP SUMMARY:
==574035==     in use at exit: 20 bytes in 1 blocks
==574035==   total heap usage: 2 allocs, 1 frees, 1,044 bytes allocated
==574035==
==574035== LEAK SUMMARY:
==574035==    definitely lost: 20 bytes in 1 blocks
==574035==    indirectly lost: 0 bytes in 0 blocks
==574035==      possibly lost: 0 bytes in 0 blocks
==574035==    still reachable: 0 bytes in 0 blocks
==574035==         suppressed: 0 bytes in 0 blocks
==574035== Rerun with --leak-check=full to see details of leaked memory
==574035==
==574035== For lists of detected and suppressed errors, rerun with: -s
==574035== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)