Error(s):

source_file.c: In function ‘fun2’:
source_file.c:18:5: warning: function returns address of local variable [-Wreturn-local-addr]
     return &a;
     ^
source_file.c: In function ‘main’:
source_file.c:42:3: error: unknown type name ‘echo’
   echo hello
   ^
source_file.c:44:12: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘return’
            return 1;
            ^