foo.cc: In function 'Matrix3& operator+(Matrix3&, Matrix3&)':
foo.cc:34:9: warning: reference to local variable 'tmp' returned [-Wreturn-local-addr]
34 | return tmp;
| ^~~
foo.cc:28:10: note: declared here
28 | Matrix3 tmp;
| ^~~
foo.cc: In function 'Matrix3& operator-(Matrix3&, Matrix3&)':
foo.cc:43:9: warning: reference to local variable 'tmp' returned [-Wreturn-local-addr]
43 | return tmp;
| ^~~
foo.cc:37:10: note: declared here
37 | Matrix3 tmp;
| ^~~
foo.cc: In function 'Matrix3& operator*(Matrix3&, int)':
foo.cc:52:9: warning: reference to local variable 'tmp' returned [-Wreturn-local-addr]
52 | return tmp;
| ^~~
foo.cc:46:10: note: declared here
46 | Matrix3 tmp;
| ^~~
foo.cc: In function 'Matrix3& operator*(Matrix3&, Matrix3&)':
foo.cc:61:9: warning: reference to local variable 'tmp' returned [-Wreturn-local-addr]
61 | return tmp;
| ^~~
foo.cc:55:10: note: declared here
55 | Matrix3 tmp;
| ^~~
[Hydro](https://hydro.ac)提供评测服务