[Bug libfortran/113313] execute_command_line hangs at run time

["kargl at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113313

kargl at gcc dot gnu.org changed:

           What    |Removed                     |Added
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           Priority|P3                          |P4

--- Comment #5 from kargl at gcc dot gnu.org ---
(In reply to Jerry DeLisle from comment #4)
> I just started looking at this today. I will give the patch a spin in the
> next few days and if tests OK I can commit.
> 
> John, are you able tp apply Steve's patch and try it? If not would you like
> to learn how?  I can show people the ropes.  We have a MatterMost workspace
> you can join and I can linkup with you there. (I will send you an invite,
> just let me know.)

Jerry, there are 2 paths through the function execute_command_line()
in execute_command_line.c  One is for synchronous execution and one
is for asynchronous.  For async, exitstat is untouched.  For synchronous,
exitstat is set.

   EXITSTAT (optional) shall be a scalar of type integer with a decimal
   exponent range of at least nine.  It is an INTENT(INOUT) argument. If
   the command is executed synchronously, it is assigned the value of the
   processor-dependent exit status. Otherwise, the value of EXITSTAT is
   unchanged.

If I read the code correctly, it tries to save a copy of the input
value of exitstat, and then uses that to compare to the returned
value.  if exitstat is present, then is should simply be set to
the return value.