[Bug fortran/119136] Printing result of function that prints itself hangs

[jvdelisle at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119136

--- Comment #17 from Jerry DeLisle <jvdelisle at gcc dot gnu.org> ---
(In reply to Jerry DeLisle from comment #16)
> (In reply to Thomas Koenig from comment #15)
> > (In reply to Jerry DeLisle from comment #14)

> > Regarding the logic:  I think we have the potential for race conditions
> > here.  I would suggest something like (completely untested)
> > 
> 
> Theoretically this check is done outside of locking sequences. I dont have a
> problem adding a trylock and testing it.
> 
> --- snip ---

With the TRYLOCK we get a boat load of regressions. In thinking about it, I
think my original patch is safe because in that section of code we are not
doing any I/O, we are simply checking the flag and setting it.  We are not
clearing the flag until after all the I/O has completed.

Regarding internal units, one can think of it as also not doing any I/O we are
simply reading and writing to strings local to the program executable. I
created a string version of the test case to see what it does. I get the same
results as flang. I dont have another compiler set up to see what thay do with
internal units.  I will attach that test case.