package pkg type T1 struct{} type T2 struct{} type T3 struct{} type T4 struct{} func (T1) Write(b []byte) (int, error) { b = append(b, '\n') // want `io\.Writer\.Write must not modify the provided buffer` _ = b return 0, nil } func (T2) Write(b []byte) (int, error) { b[0] = 0 // want `io\.Writer\.Write must not modify the provided buffer` return 0, nil } func (T3) Write(b []byte) string { b[0] = 0 return "" } func (T4) Write(b []byte, r byte) (int, error) { b[0] = r return 0, nil }