foo.cc:61:34: warning: multi-character character constant [-Wmultichar]
   61 |                         char L = '/0';
      |                                  ^~~~
foo.cc:62:34: warning: multi-character character constant [-Wmultichar]
   62 |                         char R = '/0';
      |                                  ^~~~
foo.cc: In member function 'void LinkStack::Match(char*)':
foo.cc:61:34: warning: overflow in conversion from 'int' to 'char' changes value from '12080' to ''0'' [-Woverflow]
   61 |                         char L = '/0';
      |                                  ^~~~
foo.cc:62:34: warning: overflow in conversion from 'int' to 'char' changes value from '12080' to ''0'' [-Woverflow]
   62 |                         char R = '/0';
      |                                  ^~~~
foo.cc:91:46: warning: unused variable 't' [-Wunused-variable]
   91 |                                         char t = pop();
      |                                              ^
foo.cc:61:30: warning: variable 'L' set but not used [-Wunused-but-set-variable]
   61 |                         char L = '/0';
      |                              ^
foo.cc:112:33: warning: unused variable 'a' [-Wunused-variable]
  112 |                         if (int a = empty() == true)
      |                                 ^

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