foo.cc: In constructor 'Charz::Charz()':
foo.cc:27:13: warning: unused variable 'i' [-Wunused-variable]
   27 |         int i;
      |             ^
foo.cc: In member function 'int Charz::Length(char*)':
foo.cc:44:28: warning: value computed is not used [-Wunused-value]
   44 |         for (; *a != '\0'; *a++, i++) {}
      |                            ^~~~
foo.cc: In member function 'Charz& Charz::Concat(Charz&)':
foo.cc:82:16: warning: reference to local variable 'c' returned [-Wreturn-local-addr]
   82 |         return c;
      |                ^
foo.cc:76:15: note: declared here
   76 |         Charz c(*this);
      |               ^
foo.cc: In member function 'Charz& Charz::ChangeName(Charz&, Charz&)':
foo.cc:118:16: warning: reference to local variable 'c' returned [-Wreturn-local-addr]
  118 |         return c;
      |                ^
foo.cc:95:15: note: declared here
   95 |         Charz c(*this);
      |               ^

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