https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78661
--- Comment #17 from janus at gcc dot gnu.org --- (In reply to paul.richard.tho...@gmail.com from comment #16) > I suppose that one would have to set up the namelist or the input > stream to determine what the dynamic type is, have the code allocate > the variable to that type and then do the input. Huh, is it actually valid to do input on an unallocated CLASS (or TYPE) variable? If it is, one can only rely on the declared type for choosing the input procedure. When doing input on an allocated variable, which has a well-defined dynamic type, one can certainly do a polymorphic call of the input procedure. > Best of all would be that namelist incorporated constructors :-) Yes, that would also determine the dynamic type, but I assume the Fortran standard does not support anything like this? > I see no reason to require that both input and output be present. Good. Then my patch is partially wrong and incomplete.