[Bug libfortran/30617] Implement a run time diagnostic for invalid recursive I/O

[Bug libfortran/30617] Implement a run time diagnostic for invalid recursive I/O

[dominiq at lps dot ens.fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30617

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
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                 CC|                            |stefano.borini at ferrara
                   |                            |dot linux.it

--- Comment #36 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2013-02-27 18:18:38 UTC ---
*** Bug 51286 has been marked as a duplicate of this bug. ***

[Bug libfortran/30617] Implement a run time diagnostic for invalid recursive I/O

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=30617

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
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                 CC|                            |peter.machon at arcor dot de

--- Comment #37 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
*** Bug 61251 has been marked as a duplicate of this bug. ***

[Bug libfortran/30617] Implement a run time diagnostic for invalid recursive I/O

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=30617

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
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                 CC|                            |jannis at teunissen dot net

--- Comment #38 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
*** Bug 62000 has been marked as a duplicate of this bug. ***

[Bug libfortran/30617] Implement a run time diagnostic for invalid recursive I/O

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=30617

--- Comment #39 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Dominique d'Humieres from comment #29)
> > It is hanging on undefined, I think there is a difference here, a big
> > difference.
> 
> What is the difference for you?
> 
> Just as a side note, that's not me who classed the PR as invalid and so far
> I did not see a class "ICE on undefined".

Just because you've mentioned this PR:
There is a significant difference.  ICE on invalid is something clearly
undesirable, because it is the compiler that is crashing, and compiler should
not have undefined behavior on whatever garbage you throw at it.
If you compile code with undefined behavior in it, run it and that code
crashes, hangs or formats your disk, that is a bug in the code you are running,
not in the compiler.  Anything can happen when you invoke undefined behavior.
And anything includes hanging, segfault, formatting your disk etc.
E.g. if you invoke undefined behavior in some loop, gcc will often optimize
away loop bound checks in that case (on the assumption that in valid code, the
loop e.g. could be invoked only certain number of iterations and not more). 
So, you may very well get a hang in that case too.

[Bug libfortran/30617] Implement a run time diagnostic for invalid recursive I/O

[sidio47 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=30617

Cyrus <sidio47 at hotmail dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |sidio47 at hotmail dot com

--- Comment #40 from Cyrus <sidio47 at hotmail dot com> ---
*** Bug 63561 has been marked as a duplicate of this bug. ***

[Bug libfortran/30617] Implement a run time diagnostic for invalid recursive I/O

[fxcoudert at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=30617

Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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   Last reconfirmed|2007-03-03 13:31:17         |2015-8-26
                 CC|                            |fxcoudert at gcc dot gnu.org

--- Comment #41 from Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #39)
> Anything can happen when you invoke undefined behavior.

Yes. Yet, as a "quality of implementation" issue, it is desirable for us to
detect and error out on recursive I/O. Simply as indicated by the number of
duplicates of this bug, it's a common occurrence (currently on Darwin, but I
think there is no guarantee that the deadlocks don't start manifesting
themselves anytime on another platform).

The question is: can we do it with the current lock implementation? Do we have
a way to check, when we want to acquire that lock (get_external_unit), in the
case where the lock is already held, whether it's by the same thread or not.
I.e., prevent the deadlock.

I don't know how the gthread API works, but POSIX threads allow that if I read
correctly: using a PTHREAD_MUTEX_ERRORCHECK-type mutex and check for EDEADLK on
pthread_mutex_lock(). Jakub, does this sound possible the way I propose it?

[Bug libfortran/30617] Implement a run time diagnostic for invalid recursive I/O

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=30617

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
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                 CC|                            |anthony.debeus at gmail dot com

--- Comment #42 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
*** Bug 98046 has been marked as a duplicate of this bug. ***

[Bug libfortran/30617] Implement a run time diagnostic for invalid recursive I/O

[dominiq at lps dot ens dot fr]

------- Comment #35 from dominiq at lps dot ens dot fr  2009-12-14 20:51 -------
Wrong pr. Sorry for the noise.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30617

[Bug libfortran/30617] Implement a run time diagnostic for invalid recursive I/O

[dominiq at lps dot ens dot fr]

------- Comment #34 from dominiq at lps dot ens dot fr  2009-12-14 20:45 -------
Created an attachment (id=19297)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19297&action=view)
assembly generated without -frename-registers


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30617

[Bug libfortran/30617] Implement a run time diagnostic for invalid recursive I/O

[dominiq at lps dot ens dot fr]

------- Comment #33 from dominiq at lps dot ens dot fr  2009-12-14 20:43 -------
Created an attachment (id=19296)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19296&action=view)
assembly generated with -frename-registers


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30617

[Bug libfortran/30617] Implement a run time diagnostic for invalid recursive I/O

[dominiq at lps dot ens dot fr]

------- Comment #32 from dominiq at lps dot ens dot fr  2009-05-07 22:00 -------
Presently invalid recursive I/Os are accepted by gfortran without any
diagnostic at run time. It could be helpful to implement such a diagnostic with
something such as -fcheck=recursive_IO.

Note that xlf gives a run time error for invalid recursive I/Os.


-- 

dominiq at lps dot ens dot fr changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fxcoudert at gmail dot com
 GCC target triplet|*-apple-darwin*             |
           Keywords|                            |diagnostic
            Summary|recursive I/O hangs under   |Implement a run time
                   |OSX                         |diagnostic for invalid
                   |                            |recursive I/O


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30617