foo.cc: In member function 'Complex Complex::operator*(Complex&)':
foo.cc:21:7: warning: unused variable 'rr' [-Wunused-variable]
   21 |   int rr = c.re, ii = c.im;
      |       ^~
foo.cc:21:18: warning: unused variable 'ii' [-Wunused-variable]
   21 |   int rr = c.re, ii = c.im;
      |                  ^~
foo.cc: In function 'void test01()':
foo.cc:56:11: error: cannot bind non-const lvalue reference of type 'Complex&' to an rvalue of type 'Complex'
   56 |  C = c1+c2+c3;
      |      ~~~~~^~~
foo.cc:27:28: note:   initializing argument 1 of 'void Complex::operator=(Complex&)'
   27 |  void operator = (Complex &c)
      |                   ~~~~~~~~~^
foo.cc:59:12: error: cannot bind non-const lvalue reference of type 'Complex&' to an rvalue of type 'Complex'
   59 |  C1 = c1*c2*c3;
      |       ~~~~~^~~
foo.cc:27:28: note:   initializing argument 1 of 'void Complex::operator=(Complex&)'
   27 |  void operator = (Complex &c)
      |                   ~~~~~~~~~^

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