select type failure?

[Andrew Benson]

The attached code produces unexpected behavior (and a segfault) when compiled 
using gfortran 4.6 r170207:

$ gfortran test.F90 -o test.exe -g -fbacktrace
$ test.exe
 incorrect

Program received signal 11 (SIGSEGV): Segmentation fault.

Backtrace for this error:
  + [0x40000420]
  + function __tree_nodes_MOD_merger_tree_construction_walk (0x80486F3)
    at line 24 of file test.F90
  + function __merger_tree_build_MOD_merger_tree_build_do (0x804877D)
    at line 65 of file test.F90
  + function test (0x80487ED)
    at line 78 of file test.F90
  + /lib/libc.so.6(__libc_start_main+0xdc) [0x24be9c]

Assuming that my code is valid (it is as far as I can tell, but if not I'd be 
happy to hear what I'm doing wrong) then I would expect the "select type" 
construct to execute the contents of the "type is (treeNode)" block and not 
the "class default" block. As a result of it failing to do this the workNode 
pointer is unassigned and then causes a segfault when I try to access 
workNode%childNode

I've attempted to reduce the code further, but began running into other 
complaints from the compiler, e.g.:

undefined reference to `__merger_tree_build_MOD___vtab_tree_nodes_Treenode'

so I figured I'd stop and double check that this is an actual compiler bug 
before going any further.

Thanks,
Andrew.

-- 

* Andrew Benson: http://www.tapir.caltech.edu/~abenson/contact.html

* Galacticus: http://sites.google.com/site/galacticusmodel
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