[fortran,patch] Creating a common header to the front-end and runtime library

[Tobias Schlüter]

François-Xavier Coudert wrote:
> Since this is mostly moving things around, I'd like your comments on
> whether this is something we want for gfortran; I am convinced that
> it's a clear win, but please step in and give your opinion. So, if a
> consensus appears [1], I'll commit the patch in a few days, taking
> into account all amendments made at that point.

I think it's a clear win.  Note that the library needs the compiler to 
be built, not the other way round, so it might make more sense to put 
the common file in gcc/fortran.  I see that you haven't added Makefile 
rules for the dependency.  With my supposed change you could do without 
cross-directory dependencies (just rebuild the library everytime the 
compiler changes), but this is far from optimal.  How do other frontends 
handle this kind of things?

One alternative approach that I could think of is having a compiler flag 
that allows the compiler to dump a header file for the library.  Then, 
while building the library you do
  gfortran --dump-compatibility-stuff > include/libgfortran_fe.h

This wouldn't solve the dependency issues, though.

Cheers,
- Tobi