m4 expert needed

[Steve Kargl]

So who's our resident m4 expert?  Anyone have a favorite
on-line m4 tutorial?

Here's the problem:  we need to autogenerate the TRANSFER
functions for libgfortran when either SOURCE or MOLD is an
array.  If SOURCE and MOLD are both scalar, then tran-intrinsic.c
appears to automagically build appropriate SSA trees.  If
either SOURCE or MOLD is non-scalar, we need library routines.

So, we have TRANSFER(SOURCE,MOLD,[SIZE]) with SIZE optional.
SOURCE and MOLD can be any type and scalar or array.  This
means we need 

  SOURCE: character, logical(1,2,4,8), integer(1,2,4,8),
          real(4,8,[10,16]), complex(4,8,[10,16])

          13 to 17 source type and kind types

   MOLD:  ditto.

So, 13*13 = 169 and 17*17 = 289 functions.

Things may not be that bad.  We should be able to transform 
a certain number of the 169 to 289 into loops over the
scalar-scalar case except we need to be mindful of the difference
between an array section and an array element.  For example,

program t
   integer i
   real a, b, x(4), y(4)
   complex c, z(2)

   x = (/1.1, 2.2, 3.3, 4.4/)
   c = (0.,0.)
   a = 1.
   b = x(1)

   ! Need _gfortran_transfer_r4a_c4s
   ! r4a == real(4) array
   ! c4s == complex(4) scalar
   z = transfer(x, c)
   print '(4f5.1)', z

   ! Need _gfortran_transfer_r4a_r4s
   ! r4a == real(4) array
   ! r4s == real(4) scalar
   y = transfer(x, a)
   print '(4f5.1)', y
   !
   ! Equivalent loop over scalar-scalar case.
   !
   do i = 1, 4
      write(*,'(f5.1)',advance='no') transfer(b, a)
   end do
   print *
end program t

Comments?

-- 
Steve