linked lists/trees with type-bound procedures

[Tobias Burnus]

  Hi Mark,

Mark Rashid wrote:
> Attached is a short source file containing a single (self-contained) module
> that produces the errors I mentioned when compiled with gfortran 4.5.  I
> have not yet tried 4.6.

I can reproduce the error with gfortran 4.5.1, however, using gfortran 
4.6 it compiles without any error or warning.

GCC 4.6 binaries are available from http://gcc.gnu.org/wiki/GFortranBinaries

An overview about the 4.5 and 4.6 work regarding polymorphic data types 
(CLASS) and the other ingredients of object-oriented programming can be 
found at:http://gcc.gnu.org/wiki/OOP
As you can see there, 34 bugs (some small, some large) were already 
fixed in 4.6 - seemingly that includes yours.

Tobias

PS: Unfortunately, adding a fully working support for polymorphism takes 
a while - and like always in volunteer-based open-source projects, there 
are ups and downs in the activity of the developers.* And a helping hand 
is always welcome - as are bug reports with small examples. Thus, thanks 
for the bug report.

* Actually, the result of the work since 4.5 (i.e. April 2010) is quite 
impressive; for OOP see the link above, for a general overview look at 
http://gcc.gnu.org/gcc-4.6/changes.html#Fortran
Since 4.6 work has started, a diffstat shows
  71 files changed, 17923 insertions(+), 8332 deletions(-)
(That's without back-end changes, library changes, and without test cases.)