[Bug fortran/64654] New: problem of handling character arguments in parent of an 'entry' with fewer arguments leads at -O0

["d.pashov at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64654

            Bug ID: 64654
           Summary: problem of handling character arguments in parent of
                    an 'entry' with fewer arguments leads at -O0
           Product: gcc
           Version: 4.8.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: d.pashov at gmail dot com

Created attachment 34474
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34474&action=edit
test case

Incorrect code is generated with -O0 or -fcheck=all for a subroutine having a
character argument of passed length and which also contains entries with
different (or fewer) arguments. Example test case is attached. 

The executable crashes with SIGSERV right after entering the entry, before the
first executable statement in the entry. I suspect it tries to resolve the
charater arguments of the parent subroutine routine which have their 'len'
passed. It does not happen for other arguments or len=* or array arguments.
Some samples are in the example file.

The problem seemigly goes away for -O1 and higher optimisation levels if
-fcheck=all is not used. While the program the works as expected it makes
debugging inconvenient. I did check the f2008 standard carefully and came to
the conclusion that the code is not doing anything in violation.

I have found it on v4.8.1 and have the impresison that it did not exist some
time before but could not find a working version (only tried 4.6). v4.8.3,
v4.9.0 and 5.0 also have the bug.

Results of running the code with varios configurations are in a comment in the
attached file.