From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
 id 650DE3857007; Wed,  1 Jul 2020 11:39:25 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 650DE3857007
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
 s=default; t=1593603565;
 bh=ZVlG8sQ1PLAn0GOVjZL8t5G6cq41NFDF5srHumBndoA=;
 h=From:To:Subject:Date:From;
 b=PT7OVmmQr7VNYnFn3T6APO6t3/MKhWDqwqPA37Ye6AbWLp6KZCRMBaJ56nJdYeVv2
 xG9rYSmSSzIxlQowSQbZM9b0lVs3rjfXH23V6nBb4wgCWqvHUSBFl32WwpdPmAfes0
 eJXif/TLmClfB3HQh+DvO07GLqqgJ2t9EQ2Td26o=
From: "martin.schlipf at damnthespam dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/96018] New: Optimization issue with external HDF5 library
Date: Wed, 01 Jul 2020 11:39:25 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: fortran
X-Bugzilla-Version: 10.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: martin.schlipf at damnthespam dot com
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
 attachments.created
Message-ID: <bug-96018-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <http://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <http://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Wed, 01 Jul 2020 11:39:25 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D96018

            Bug ID: 96018
           Summary: Optimization issue with external HDF5 library
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: martin.schlipf at damnthespam dot com
  Target Milestone: ---

Created attachment 48817
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D48817&action=3Dedit
Minimal example to demonstrate the issue.

On a clean Ubuntu 20.04 with the following setup

sudo apt-get update
sudo apt-get install gfortran-10
sudo apt-get install libhdf5-dev

the attached code produces an error when compiled with optimization

gfortran-10 -O2 hdf5_bug.f90 -I/usr/include/hdf5/serial/
-L/usr/lib/x86_64-linux-gnu/ -lhdf5_serial_fortran

As far as I can tell, the reason this appears is that the compiler fails to
recognize that the function call in line 98 has side effects and optimizes =
it
away. If you check the status of the error code, the issue disappears.
Strangely, the exact same sequence of calls with a 2d array instead of a 3d=
 one
works fine.=