From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-410377-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 9832 invoked by alias); 20 Dec 2012 15:07:33 -0000
Received: (qmail 7612 invoked by uid 48); 20 Dec 2012 15:07:09 -0000
From: "burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/55758] New: LOGICAL and BIND(C): Reject kind=2/4/8/16 with -std=f2008, improve warning, switch to nonBOOLEAN_TYPE for those
Date: Thu, 20 Dec 2012 15:07:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: fortran
X-Bugzilla-Keywords: accepts-invalid, diagnostic
X-Bugzilla-Severity: normal
X-Bugzilla-Who: burnus at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Changed-Fields:
Message-ID: <bug-55758-4@http.gcc.gnu.org/bugzilla/>
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
X-SW-Source: 2012-12/txt/msg01985.txt.bz2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55758

             Bug #: 55758
           Summary: LOGICAL and BIND(C): Reject kind=2/4/8/16 with
                    -std=f2008, improve warning, switch to nonBOOLEAN_TYPE
                    for those
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Keywords: accepts-invalid, diagnostic
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: burnus@gcc.gnu.org


See http://gcc.gnu.org/ml/fortran/2012-12/threads.html#00135

In the Fortran standard, only LOGICALs of kind C_BOOL interoperate with C;
namely, with C99's _Bool/bool.

In C, also integers - in particular "int" - are used in Boolean expressions,
allows for the whole range of integral values - all are "true" except for 0
which is "false".

gcc's _Bool and gfortran's LOGICAL all assume a binary state (BOOLEAN_TYPE)
which is either 0 or 1 such that .NOT. can be implemented by flipping a single
bit.

Hence, regarding an "int" as BOOLEAN_TYPE leads to .NOT.(-1) = -2.


Currently, LOGICAL(kind=C_INT) (c_int == 4) is accepted by gfortran and C
binding, but it might lead to wrong results with .NOT.


Expected:
* With -std=f95/f2003/f2008/f2008tr, only LOGICAL with kind=C_BOOL (C_BOOL ==
1) is accepted
* With -std=gnu, also the others (2,4,8,16) are accepted but a warning is
printed for them.
* Consider replacing internally BOOLEAN_TYPE by a signed-integer type LOGICAL
with kind /= C_BOOL in procedures with C binding