PVS-Studio warning V520 for GLG3D

void AnyVal::serialize(G3D::TextOutput& t) const {
  ...
  const Matrix3& m = *(Matrix3*)m_value;
  ...
  t.printf("%10.5f, %10.5f, %10.5f,\n"
           "%10.5f, %10.5f, %10.5f,\n"
           "%10.5f, %10.5f, %10.5f)",
           m[0, 0], m[0, 1], m[0, 2],
           m[1, 0], m[1, 1], m[1, 2],
           m[2, 0], m[2, 1], m[2, 2]);
  ...
}

This is what should have been written here: ...., m[0][0], m[0][1], ....

This suspicious code was found in GLG3D project by PVS-Studio static code analyzer.
Warning message is:
V520 The comma operator ',' in array index expression '[0, 0]'. graphics3D anyval.cpp 275

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