title: expected ‘struct matrix_t *’ but argument is of type ‘struct matrix_t *’ ?_? no difference
body: <pre><code>main.c:78:25: erreur: assignment from incompatible pointer type [-Werror]
  main.c:81:9: erreur: passing argument 2 of ‘matrix_multiply’ from incompatible pointer type [-Werror]
  main.c:6:11: note: expected ‘struct matrix_t *’ but argument is of type ‘struct matrix_t *’
  </code></pre>
  
  <p>line 6 is the matrix_multiply function</p>
  
  <p>here is my code which begin at line 74</p>
  
  <pre><code>matrix_t *m;
  matrix_t *first = matrix_reader_next(reader);
  matrix_t *previous = first;
  while ( (m = matrix_reader_next(reader))) {
      previous-&gt;next = m;
      previous = m;
  }
  matrix_t *result = matrix_multiply(first,first-&gt;next);
  </code></pre>
  
  <p>and here are my function prototypes and structure</p>
  
  <pre><code>typedef struct {
     int **M;
     int nLi;
     int nCo;
     struct matrix_t *next;
  } matrix_t;
  
  matrix_t* matrix_multiply(matrix_t* first, matrix_t*second);
  matrix_t* matrix_reader_next(matrix_reader_t *r);
  </code></pre>
  
  <p>I really don't understand these error message. Please help me :)</p>