Re: [Patch, libfortran] PR 48915 Fix incorrect return code with -fdump-core, error handling changes

[Tobias Burnus <burnus at net-b dot de>]

Janne Blomqvist wrote:
> >  I disagree with the ERROR STOP change.
> My thinking is that the spirit of ERROR STOP is that the program
> noticed something went seriously wrong (e.g. program state corrupted
> in some way), and  hence a backtrace and/or core dump might help
> figure out what went wrong. For less serious errors, there's the plain
> STOP. Similar to how in C there's exit() and abort().

Well, typical usages would be:
  STOP "Calculation finished"
and
  ERROR STOP "No input file found"

Admittedly, STOP is also used for the latter as there was no ERROR STOP 
until Fortran 2008 - and when using numerical arguments, the value is 
also used as exit status code - with string values, which are rather 
common, STOP has always the success exit status code 0.

Especially with coarrays, one cannot easily prevent the usage of ERROR 
STOP: Assume that this_image() > 1 processes wait for process 1 ("SYNC 
IMAGES(1)") to read in the data and to broadcast it. Now, process 1 sees 
that there is no input file - what shell it do? A STOP would cause a 
dead lock. Thus, one simply calls ERROR STOP "No input file" - and does 
not want to have a backtrace ...

As written, before if one is able to call STOP or ERROR STOP, one knows 
where one is in the program - and at least roughly why one stops there. 
Thus, at least by default, I don't want to have a backtrace. If one had 
a "-fbacktrace=always" or similar, one could still backtrace ERROR STOP 
- and maybe even STOP ;-)

Maybe, we should make the backtrace functionality available like other 
compilers have; looking at our code, I find for Intel
  USE ifcore
  CALL tracebackqq(USER_EXIT_CODE=-1)
and for IBM
  CALL xl__trbk()

Tobias