Re: optimization/697

Re: optimization/697

[rth]

The following reply was made to PR optimization/697; it has been noted by GNATS.

From: rth@gcc.gnu.org
To: Mike@arl.army.mil, acst@arl.army.mil, gcc-gnats@gcc.gnu.org,
  nobody@gcc.gnu.org
Cc:  
Subject: Re: optimization/697
Date: 16 Jan 2001 15:50:21 -0000

 Synopsis: 2.96 20000731 (Red Hat Linux 7.0) generates bad linked list code on -O2, working code on -O1 or -g
 
 State-Changed-From-To: open->closed
 State-Changed-By: rth
 State-Changed-When: Tue Jan 16 07:50:21 2001
 State-Changed-Why:
     The function rt_free_pt_list accesses the same memory as a
     struct bu_list and as a struct partition.  This violates ISO C
     type aliasing rules.
     
     As a gcc extension you may access the same memory as different
     types via a union.  Note that there is *no* portable way to do
     this in ISO C.
     
     Alternately, compile with -fno-strict-aliasing to disable the
     type-based aliasing rules entirely.
 
 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view&pr=697&database=gcc
>From David.Billinghurst@riotinto.com Sun Apr 01 00:00:00 2001
From: David.Billinghurst@riotinto.com
To: gcc-gnats@gcc.gnu.org
Subject: c/1872: bootstrap failure on irix6.5 - identifier "MASK_FLAG64" is undefined
Date: Sun, 01 Apr 2001 00:00:00 -0000
Message-id: <20010204233300.32587.qmail@sourceware.cygnus.com>
X-SW-Source: 2001-q1/msg00957.html
Content-length: 919

>Number:         1872
>Category:       c
>Synopsis:       bootstrap failure on irix6.5 - identifier "MASK_FLAG64" is undefined
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Feb 04 15:36:00 PST 2001
>Closed-Date:
>Last-Modified:
>Originator:     David Billinghurst
>Release:        CVS 20010204
>Organization:
>Environment:
mips-sgi-irix6.5
>Description:
While bootstrapping with Irix cc (MIPSpro 7.2.1) if get the error

"/exd4/billingd/src/gcc/gcc/config/mips/mips.c", line 4958: error(1020): 
          identifier "MASK_FLAG64" is undefined
          target_flags &= ~ MASK_FLAG64;
 
I cannot find a definition of MASK_FLAG64 in the gcc source tree or /usr/include

>How-To-Repeat:
Configure and bootstrap with CC=cc on irix6.5
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
>From dmuell@gmx.net Sun Apr 01 00:00:00 2001
From: dmuell@gmx.net
To: gcc-gnats@gcc.gnu.org
Subject: c++/2110: compile error in function pointer cast (regression from 2.95)
Date: Sun, 01 Apr 2001 00:00:00 -0000
Message-id: <200102270112.f1R1CvF07790@rotes20.wohnheim.uni-kl.de>
X-SW-Source: 2001-q1/msg01773.html
Content-length: 1369

>Number:         2110
>Category:       c++
>Synopsis:       compile error due to method function pointer cast
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Mon Feb 26 17:16:01 PST 2001
>Closed-Date:
>Last-Modified:
>Originator:     Dirk Mueller
>Release:        3.0 20010226 (prerelease)
>Organization:
>Environment:
Linux 2.4.2 
Architecture: i686
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: ../configure --enable-threads --enable-shared --enable-languages=c,c++
>Description:

try to compile this code: 

=== Cut ===
class fooObject {};
typedef void (fooObject::*Func)();
class foobar : public fooObject {
    void add(Func fncHandler);
    void somefunc();
    void init() { add(static_cast<Func>(&(foobar::somefunc))); }
};
=== Cut ===

The code might look a bit stupid, its a minimum testcase. the actual code
is different. 

command line: 
#g++ -c foobar.cpp

error message: 

invalid static_cast from type `<unknown type>' to type `void (fooObject::*)()'

Code compiles fine with any previous gcc/egcs release. Is broken
with gcc CVS for quite a while already. 

>How-To-Repeat:
read description
>Fix:
unknown. urgently needed. 
>Release-Note:
>Audit-Trail:
>Unformatted: