[Bug libstdc++/14493] New: new: No std::bad_alloc::what() const

[Bug libstdc++/14493] New: new: No std::bad_alloc::what() const

[debian-gcc at lists dot debian dot org]

[forwarded from http://bugs.debian.org/236912]

std::bad_alloc doesn't seem to define a what() (std par. 18.4.2.1) 
leading to unintelligible error messages.

-- 
           Summary: new: No std::bad_alloc::what() const
           Product: gcc
           Version: 3.4.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: debian-gcc at lists dot debian dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] new: No std::bad_alloc::what() const

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-03-08 22:36 -------
Confirmed a bug, but it seems like the code you have should compile as exception have a what() 
method.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2004-03-08 22:36:26
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] No std::bad_alloc::what() const

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-03-08 23:15 -------
For Andrew: the code takes the respective method of the base 
class. 
 
Here's a testcase: 
--------------- 
#include <iostream> 
#include <new> 
 
int main () 
{ 
  try 
    { 
      new char[static_cast<unsigned int>(-1)/2]; 
    } 
  catch (std::exception &e) 
    { 
      std::cerr << e.what () << std::endl; 
    } 
} 
---------------------- 
 
g/x> icc x.cc 
g/x> ./a.out  
bad allocation 
g/x>  
g/x> /home/bangerth/bin/gcc-3.5-pre/bin/c++ x.cc 
g/x> ./a.out  
St9bad_alloc 
 
I believe that libstdc++ is actually conforming, since the method exists 
(even if in the base class) and it returns an implementation defined 
string (as required by the standard). Some of the libstdc++ folks should 
comment on this. 
 
W. 

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] No std::bad_alloc::what() const

[pme at gcc dot gnu dot org]

------- Additional Comments From pme at gcc dot gnu dot org  2004-03-09 04:14 -------
Works just fine.  Submitter is mistaken.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] No std::bad_alloc::what() const

[phil at jaj dot com]

------- Additional Comments From phil at jaj dot com  2004-03-09 04:14 -------
Subject: Re:  No std::bad_alloc::what() const

close 236912
thanks

This bug report reinforces my opinion that bug reports consisting of
claims of nonconformance, but not accompanied by a testcase, should be
immediately closed.


On Mon, Mar 08, 2004 at 11:15:05PM -0000, bangerth at dealii dot org wrote:
> For Andrew: the code takes the respective method of the base 
> class. 

More to the point, it doesn't matter how it's implemented, and the user
should not care.  It only matters that

    std::bad_alloc foo;
    std::cerr << foo.what() << std::endl;

works, which the submitter didn't apparently try.  Looking at the original
Debian bug report, there are no compiler error messages, just a "my code
doesn't do what I want it to do, so it must be your fault"-style complaint.


> I believe that libstdc++ is actually conforming, since the method exists 
> (even if in the base class)

Correct.  There is no requirement on implementation, only behavior.

> and it returns an implementation defined 
> string (as required by the standard).

Correct.  As described in the documentation.



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] No std::bad_alloc::what() const

[zack at gcc dot gnu dot org]

------- Additional Comments From zack at gcc dot gnu dot org  2004-03-09 04:45 -------
It appears to me that the original reporter wanted what() to return
an "intelligible error message" a la icc's "bad allocation", rather
than "St9bad_alloc"  (which does communicate the same information but
in a more cryptic fashion).

I do think there should be a place in the standard library for nice 
friendly names for exceptions (think strerror()), but I don't know 
if what() is that place.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] No std::bad_alloc::what() const

[doko at cs dot tu-berlin dot de]

------- Additional Comments From doko at cs dot tu-berlin dot de  2004-03-09 05:19 -------
Subject: Re:  No std::bad_alloc::what() const

[resending for the inclusion to the Debian BTS]

Phil Edwards writes:
> close 236912
> thanks
> 
> This bug report reinforces my opinion that bug reports consisting of
> claims of nonconformance, but not accompanied by a testcase, should be
> immediately closed.
> 
> 
> On Mon, Mar 08, 2004 at 11:15:05PM -0000, bangerth at dealii dot org wrote:
> > For Andrew: the code takes the respective method of the base 
> > class. 
> 
> More to the point, it doesn't matter how it's implemented, and the user
> should not care.  It only matters that
> 
>     std::bad_alloc foo;
>     std::cerr << foo.what() << std::endl;
> 
> works, which the submitter didn't apparently try.  Looking at the original
> Debian bug report, there are no compiler error messages, just a "my code
> doesn't do what I want it to do, so it must be your fault"-style complaint.
> 
> 
> > I believe that libstdc++ is actually conforming, since the method exists 
> > (even if in the base class)
> 
> Correct.  There is no requirement on implementation, only behavior.
> 
> > and it returns an implementation defined 
> > string (as required by the standard).
> 
> Correct.  As described in the documentation.
> 
> 
> -- 
> To UNSUBSCRIBE, email to debian-gcc-request@lists.debian.org
> with a subject of "unsubscribe". Trouble? Contact listmaster@lists.debian.org


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] No std::bad_alloc::what() const

[jtv at xs4all dot nl]

------- Additional Comments From jtv at xs4all dot nl  2004-03-09 18:32 -------
Subject: Re:  No std::bad_alloc::what() const

On Tue, Mar 09, 2004 at 06:14:59AM +0100, Matthias Klose wrote:

> > More to the point, it doesn't matter how it's implemented, and the user
> > should not care.  It only matters that
> > 
> >     std::bad_alloc foo;
> >     std::cerr << foo.what() << std::endl;
> > 
> > works, which the submitter didn't apparently try.  Looking at the original

Apparently whoever said this hasn't seen the bug report, and it got
rephrased somewhere along the line.  I was wrong in my assumption that
std::bad_alloc should override what(), but the problem remains: the
message coming out of what(), "St9bad_alloc" is incomprehensible to
a normal user.


Jeroen



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] No std::bad_alloc::what() const

[phil at jaj dot com]

------- Additional Comments From phil at jaj dot com  2004-03-09 19:32 -------
Subject: Re: Bug#236912:  No std::bad_alloc::what() const

On Tue, Mar 09, 2004 at 07:32:32PM +0100, Jeroen T. Vermeulen wrote:
> On Tue, Mar 09, 2004 at 06:14:59AM +0100, Matthias Klose wrote:
> 
> > > More to the point, it doesn't matter how it's implemented, and the user
> > > should not care.  It only matters that
> > > 
> > >     std::bad_alloc foo;
> > >     std::cerr << foo.what() << std::endl;
> > > 
> > > works, which the submitter didn't apparently try.  Looking at the original
> 
> Apparently whoever said this hasn't seen the bug report, and it got
> rephrased somewhere along the line.

No, I read it.

> I was wrong in my assumption that
> std::bad_alloc should override what(), but the problem remains: the
> message coming out of what(), "St9bad_alloc" is incomprehensible to
> a normal user.

If you mean to complain about X, then don't complain about Y.  Don't title
your bug reports "Y is missing" when you find you don't like the behavior
of X.  Don't assume that X and Y have anything to do with one another.

The output of what() is described in the library documentation.  There is
also documentation provided on how to run the demangler on the string, e.g.,

    std::cerr << the_demangler_function(foo.what()) << std::endl;



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] No std::bad_alloc::what() const

[pme at gcc dot gnu dot org]

------- Additional Comments From pme at gcc dot gnu dot org  2004-03-09 19:48 -------
(In reply to comment #5)
> It appears to me that the original reporter wanted what() to return
> an "intelligible error message" a la icc's "bad allocation", rather
> than "St9bad_alloc"  (which does communicate the same information but
> in a more cryptic fashion).
> 
> I do think there should be a place in the standard library for nice 
> friendly names for exceptions (think strerror()), but I don't know 
> if what() is that place.

Slap a _Z on that thing and we could demangle it automatically.  The
problems with doing so are that the demangling routines are linked in
when they otherwise wouldn't be (so goes the argument, but I haven't
verified it myself).

Personally, I feel __cxa_demangler should just be present, full stop.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

Re: [Bug libstdc++/14493] No std::bad_alloc::what() const

[Zack Weinberg]

"pme at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> writes:
>> It appears to me that the original reporter wanted what() to return
>> an "intelligible error message" a la icc's "bad allocation", rather
>> than "St9bad_alloc"  (which does communicate the same information but
>> in a more cryptic fashion).
>
> Slap a _Z on that thing and we could demangle it automatically.  The
> problems with doing so are that the demangling routines are linked in
> when they otherwise wouldn't be (so goes the argument, but I haven't
> verified it myself).

Honestly, is "std::bad_alloc" really that much more readable than
"St9bad_alloc"?  Especially compared to "bad allocation"?

zw

[Bug libstdc++/14493] No std::bad_alloc::what() const

[zack at codesourcery dot com]

------- Additional Comments From zack at codesourcery dot com  2004-03-09 20:14 -------
Subject: Re:  No std::bad_alloc::what() const

"pme at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> writes:
>> It appears to me that the original reporter wanted what() to return
>> an "intelligible error message" a la icc's "bad allocation", rather
>> than "St9bad_alloc"  (which does communicate the same information but
>> in a more cryptic fashion).
>
> Slap a _Z on that thing and we could demangle it automatically.  The
> problems with doing so are that the demangling routines are linked in
> when they otherwise wouldn't be (so goes the argument, but I haven't
> verified it myself).

Honestly, is "std::bad_alloc" really that much more readable than
"St9bad_alloc"?  Especially compared to "bad allocation"?

zw


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] No std::bad_alloc::what() const

[giovannibajo at libero dot it]

------- Additional Comments From giovannibajo at libero dot it  2004-03-10 01:12 -------
(In reply to comment #10)

> Honestly, is "std::bad_alloc" really that much more readable than
> "St9bad_alloc"?  Especially compared to "bad allocation"?

Well, "St9bad_alloc" looks like memory corruption, unless you recognize it's 
part of a mangled name. I think it is counter-intuitive. Of course, the best 
would be to have a "bad allocation" string stored somewhere.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] No std::bad_alloc::what() const

[pme at gcc dot gnu dot org]

------- Additional Comments From pme at gcc dot gnu dot org  2004-03-11 07:35 -------
> Honestly, is "std::bad_alloc" really that much more readable than
> "St9bad_alloc"?

The former is at least readable C++.  More importantly, it's what 'new'
is documented as throwing, so a programmer reading (good) documentation
for operator new will see "std::bad_alloc".


>  Especially compared to "bad allocation"?

Sure, we could change that.  I don't think "bad allocation" is any
better than the demangled type name, but we shouldn't be printing
a mangled typeid.  Others felt differently.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] No std::bad_alloc::what() const

[gdr at integrable-solutions dot net]

------- Additional Comments From gdr at integrable-solutions dot net  2004-03-11 10:05 -------
Subject: Re:  No std::bad_alloc::what() const

"pme at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> writes:

| >  Especially compared to "bad allocation"?
| 
| Sure, we could change that.  I don't think "bad allocation" is any
| better than the demangled type name, but we shouldn't be printing
| a mangled typeid.  Others felt differently.

I agree with Phil that we should not have been printing the mangled
typeid.

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] No std::bad_alloc::what() const

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-03-11 15:51 -------
The let's reopen the bug. I keep wondering why there is such resistance 
to really small patches like the one needed for this PR... 
 
W. 

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] No std::bad_alloc::what() const

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-03-11 15:52 -------
. 
 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|INVALID                     |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|minor                       |enhancement
             Status|REOPENED                    |NEW
            Summary|No std::bad_alloc::what()   |std::bad_alloc::what() does
                   |const                       |not explain what happened


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[pcarlini at suse dot de]

------- Additional Comments From pcarlini at suse dot de  2004-08-05 14:37 -------
Implementing the trivial fix...

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |pcarlini at suse dot de
                   |dot org                     |
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[pcarlini at suse dot de]

------- Additional Comments From pcarlini at suse dot de  2004-08-05 15:00 -------
... actually, not so trivial, because of the need to free the memory allocated
by __cxa_demangle :(
By the way, current Icc doesn't demangle anymore.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|pcarlini at suse dot de     |unassigned at gcc dot gnu
                   |                            |dot org
             Status|ASSIGNED                    |NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

--- Comment #33 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:c73f20e67ee8d268bf0dfd6732c1bd3e79e098ca

commit r10-11323-gc73f20e67ee8d268bf0dfd6732c1bd3e79e098ca
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Apr 4 12:04:14 2023 +0100

    libstdc++: Fix outdated docs about demangling exception messages

    The string returned by std::bad_exception::what() hasn't been a mangled
    name since PR libstdc++/14493 was fixed for GCC 4.2.0, so remove the
    docs showing how to demangle it.

    libstdc++-v3/ChangeLog:

            * doc/xml/manual/extensions.xml: Remove std::bad_exception from
            example program.
            * doc/html/manual/ext_demangling.html: Regenerate.

    (cherry picked from commit 688d126b69215db29774c249b052e52d765782b3)

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

--- Comment #32 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:ee1a8294754af16b00538b17414679c8d72a575b

commit r11-10660-gee1a8294754af16b00538b17414679c8d72a575b
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Apr 4 12:04:14 2023 +0100

    libstdc++: Fix outdated docs about demangling exception messages

    The string returned by std::bad_exception::what() hasn't been a mangled
    name since PR libstdc++/14493 was fixed for GCC 4.2.0, so remove the
    docs showing how to demangle it.

    libstdc++-v3/ChangeLog:

            * doc/xml/manual/extensions.xml: Remove std::bad_exception from
            example program.
            * doc/html/manual/ext_demangling.html: Regenerate.

    (cherry picked from commit 688d126b69215db29774c249b052e52d765782b3)

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

--- Comment #31 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:e016a6ddbf0038056b9d8f2bc0bad350ff026632

commit r12-9456-ge016a6ddbf0038056b9d8f2bc0bad350ff026632
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Apr 4 12:04:14 2023 +0100

    libstdc++: Fix outdated docs about demangling exception messages

    The string returned by std::bad_exception::what() hasn't been a mangled
    name since PR libstdc++/14493 was fixed for GCC 4.2.0, so remove the
    docs showing how to demangle it.

    libstdc++-v3/ChangeLog:

            * doc/xml/manual/extensions.xml: Remove std::bad_exception from
            example program.
            * doc/html/manual/ext_demangling.html: Regenerate.

    (cherry picked from commit 688d126b69215db29774c249b052e52d765782b3)

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

--- Comment #30 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>:

https://gcc.gnu.org/g:688d126b69215db29774c249b052e52d765782b3

commit r13-6999-g688d126b69215db29774c249b052e52d765782b3
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Apr 4 12:04:14 2023 +0100

    libstdc++: Fix outdated docs about demangling exception messages

    The string returned by std::bad_exception::what() hasn't been a mangled
    name since PR libstdc++/14493 was fixed for GCC 4.2.0, so remove the
    docs showing how to demangle it.

    libstdc++-v3/ChangeLog:

            * doc/xml/manual/extensions.xml: Remove std::bad_exception from
            example program.
            * doc/html/manual/ext_demangling.html: Regenerate.

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[pcarlini at suse dot de]

------- Comment #29 from pcarlini at suse dot de  2007-02-01 15:58 -------
Fixed.


-- 

pcarlini at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[paolo at gcc dot gnu dot org]

------- Comment #28 from paolo at gcc dot gnu dot org  2007-02-01 15:56 -------
Subject: Bug 14493

Author: paolo
Date: Thu Feb  1 15:56:37 2007
New Revision: 121465

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=121465
Log:
2007-02-01  Paolo Carlini  <pcarlini@suse.de>

        PR libstdc++/14493
        * libsupc++/typeinfo (bad_cast::what, bad_typeid::what): Declare.
        * libsupc++/tinfo.cc: Define.   
        * libsupc++/exception (bad_exception::what): Declare.
        * libsupc++/eh_exception.cc: Define.
        (exception::what): Adjust, don't use typeid.
        * libsupc++/new (bad_alloc::what): Declare.
        * libsupc++/new_handler.cc: Define.
        * config/abi/pre/gnu.ver: Export the new methods @3.4.9.
        * testsuite/18_support/14493.cc: New.

2007-02-01  Paolo Carlini  <pcarlini@suse.de>

        PR libstdc++/29496
        * include/debug/safe_base.h (_Safe_sequence_base::_M_get_mutex,
        _Safe_iterator_base::_M_get_mutex, _M_attach_single, _M_detach_single):
        New.
        * src/debug.cc: Define the latter.
        (_Safe_sequence_base::_M_detach_all, _M_detach_singular,
        _M_revalidate_singular, _M_swap): Use the mutex.
        (_Safe_iterator_base::_M_attach, _M_detach): Adjust, forward to the
        *_single version.
        * include/debug/safe_iterator.h (_Safe_iterator<>::_M_attach_single,
        _M_invalidate_single): New.
        * include/debug/safe_iterator.tcc: Define.
        (_Safe_iterator<>::_M_invalidate): Adjust, forward to
        _M_invalidate_single.
        * include/debug/safe_sequence.h (_Safe_sequence<>::_M_invalidate_if,
        _M_transfer_iter): Use the mutex, adjust, forward to the *_single
        versions of _M_invalidate and _M_attach.
        * config/abi/pre/gnu.ver (_Safe_sequence_base::_M_get_mutex,
        _Safe_iterator_base::_M_get_mutex, _M_attach_single, _M_detach_single):
        Add @GLIBCXX_3.4.9; adjust.

Added:
    branches/gcc-4_2-branch/libstdc++-v3/testsuite/18_support/14493.cc
Modified:
    branches/gcc-4_2-branch/libstdc++-v3/ChangeLog
    branches/gcc-4_2-branch/libstdc++-v3/config/abi/pre/gnu.ver
    branches/gcc-4_2-branch/libstdc++-v3/include/debug/safe_base.h
    branches/gcc-4_2-branch/libstdc++-v3/include/debug/safe_iterator.h
    branches/gcc-4_2-branch/libstdc++-v3/include/debug/safe_iterator.tcc
    branches/gcc-4_2-branch/libstdc++-v3/include/debug/safe_sequence.h
    branches/gcc-4_2-branch/libstdc++-v3/libsupc++/eh_exception.cc
    branches/gcc-4_2-branch/libstdc++-v3/libsupc++/exception
    branches/gcc-4_2-branch/libstdc++-v3/libsupc++/new
    branches/gcc-4_2-branch/libstdc++-v3/libsupc++/new_handler.cc
    branches/gcc-4_2-branch/libstdc++-v3/libsupc++/tinfo.cc
    branches/gcc-4_2-branch/libstdc++-v3/libsupc++/typeinfo
    branches/gcc-4_2-branch/libstdc++-v3/src/debug.cc


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[pcarlini at suse dot de]

-- 

pcarlini at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.2.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[paolo at gcc dot gnu dot org]

------- Comment #27 from paolo at gcc dot gnu dot org  2007-02-01 13:37 -------
Subject: Bug 14493

Author: paolo
Date: Thu Feb  1 13:36:51 2007
New Revision: 121461

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=121461
Log:
2007-02-01  Paolo Carlini  <pcarlini@suse.de>

        PR libstdc++/14493
        * libsupc++/typeinfo (bad_cast::what, bad_typeid::what): Declare.
        * libsupc++/tinfo.cc: Define.   
        * libsupc++/exception (bad_exception::what): Declare.
        * libsupc++/eh_exception.cc: Define.
        (exception::what): Adjust, don't use typeid.
        * libsupc++/new (bad_alloc::what): Declare.
        * libsupc++/new_handler.cc: Define.
        * config/abi/pre/gnu.ver: Export the new methods @3.4.9; adjust
        existing 3.4.10 exports to 3.4.9.
        * configure.ac: Adjust to 6.0.9.
        * configure: Regenerate.
        * testsuite/util/testsuite_abi.cc: Update.
        * testsuite/18_support/14493.cc: New.

Added:
    trunk/libstdc++-v3/testsuite/18_support/14493.cc
Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/config/abi/pre/gnu.ver
    trunk/libstdc++-v3/configure
    trunk/libstdc++-v3/configure.ac
    trunk/libstdc++-v3/libsupc++/eh_exception.cc
    trunk/libstdc++-v3/libsupc++/exception
    trunk/libstdc++-v3/libsupc++/new
    trunk/libstdc++-v3/libsupc++/new_handler.cc
    trunk/libstdc++-v3/libsupc++/tinfo.cc
    trunk/libstdc++-v3/libsupc++/typeinfo
    trunk/libstdc++-v3/testsuite/util/testsuite_abi.cc


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[lopresti at gmail dot com]

------- Comment #26 from lopresti at gmail dot com  2007-02-01 02:17 -------
I found this PR because I tried calling what() on a bad_alloc, was surprised by
what I got, and did a search.  This is my perspective as a random end user;
make of it what you will.

I think "std::bad_alloc" is an improvement.  But I was actually expecting
what() to provide something human readable and very specific, like "out of
memory" or "heap corrupted".  In my case, I already know the exception is a
std::bad_alloc; I could generate that particular constant string myself...

I find it remarkable that this PR is almost two years old.


-- 

lopresti at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |lopresti at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[gdr at cs dot tamu dot edu]

------- Comment #25 from gdr at cs dot tamu dot edu  2007-01-30 03:53 -------
Subject: Re:  std::bad_alloc::what() does not explain what happened

"pcarlini at suse dot de" <gcc-bugzilla@gcc.gnu.org> writes:

| > However, the use of typeid is very convenient in the sense that we
| > have to defined what() only once.  Now, if we change that definition
| > in std::exception, it means that we should revisit all other exception
| > classes, such as std::runtime_error, etc.
| 
| I see, but I don't think we have to do much, because the other exception
| classes, provided in <stdexcept>, per the standard requirements are already
| overriding what() to return _M_msg.c_str(). Thus, I'm coming to the
conclusion
| that we should consistently change std::exception too and be done with it.

You're right.  I agree with your analysis.

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[pcarlini at suse dot de]

------- Comment #24 from pcarlini at suse dot de  2007-01-30 02:21 -------
(In reply to comment #23)
> From consistency point of view I would say that the change should also
> be done for std::exception.  

Right.

> However, the use of typeid is very convenient in the sense that we
> have to defined what() only once.  Now, if we change that definition
> in std::exception, it means that we should revisit all other exception
> classes, such as std::runtime_error, etc.

I see, but I don't think we have to do much, because the other exception
classes, provided in <stdexcept>, per the standard requirements are already
overriding what() to return _M_msg.c_str(). Thus, I'm coming to the conclusion
that we should consistently change std::exception too and be done with it.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[gdr at cs dot tamu dot edu]

------- Comment #23 from gdr at cs dot tamu dot edu  2007-01-30 02:11 -------
Subject: Re:  std::bad_alloc::what() does not explain what happened

"pcarlini at suse dot de" <gcc-bugzilla@gcc.gnu.org> writes:

| ------- Comment #22 from pcarlini at suse dot de  2007-01-30 01:42 -------
| (In reply to comment #21)
| > I suspect Andrew Pinski's point might be that what() could return a
| > string that represents the name of the most derived type of the
| > exception.  But, nothing so far forces to do that.  A reasonable
| > definition is to what Paolo suggest, with clear documentation (that
| > mentions this).
| 
| Agreed. Gaby, do you have any strong opinion about std::exception
| itself? In my current patch draft I'm leaving it alone, but in
| principle we could change also its what() to return "std::exception"
| instead of typeid(*this).name(). 

>From consistency point of view I would say that the change should also
be done for std::exception.  

However, the use of typeid is very convenient in the sense that we
have to defined what() only once.  Now, if we change that definition
in std::exception, it means that we should revisit all other exception
classes, such as std::runtime_error, etc.

I have no strong opinion.  Probably just leave it as is, and document
the choices we face so that people see the rationale behind the
implementations.

Thanks,

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[pcarlini at suse dot de]

------- Comment #22 from pcarlini at suse dot de  2007-01-30 01:42 -------
(In reply to comment #21)
> I suspect Andrew Pinski's point might be that what() could return a
> string that represents the name of the most derived type of the
> exception.  But, nothing so far forces to do that.  A reasonable
> definition is to what Paolo suggest, with clear documentation (that
> mentions this).

Agreed. Gaby, do you have any strong opinion about std::exception itself? In my
current patch draft I'm leaving it alone, but in principle we could change also
its what() to return "std::exception" instead of typeid(*this).name(). In other
terms, I'm not sure whether your Comment #13 contrary to the mangled typeid
applies also to the base std::exception...


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[gdr at cs dot tamu dot edu]

------- Comment #21 from gdr at cs dot tamu dot edu  2007-01-30 01:30 -------
Subject: Re:  std::bad_alloc::what() does not explain what happened

"pcarlini at suse dot de" <gcc-bugzilla@gcc.gnu.org> writes:

| What do you mean by "incorrect"?!? If you subclass, either you
| provide your own what(), or you get the what() provided by the base
| class, which is implementation defined and, very reasonably,
| "std::bad_cast" for class bad_cast, and so on... 

Paolo is technically right: what() is a virtual member function; so
one should not derive from those classes and except that what()
returned something they did not define or we did not promise.

I suspect Andrew Pinski's point might be that what() could return a
string that represents the name of the most derived type of the
exception.  But, nothing so far forces to do that.  A reasonable
definition is to what Paolo suggest, with clear documentation (that
mentions this). 

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[pcarlini at suse dot de]

------- Comment #20 from pcarlini at suse dot de  2007-01-30 00:58 -------
(In reply to comment #19)
> I don't think that is the correct solution as if you subclass these functions,
> you get the incorrect result.

What do you mean by "incorrect"?!? If you subclass, either you provide your own
what(), or you get the what() provided by the base class, which is
implementation defined and, very reasonably, "std::bad_cast" for class
bad_cast, and so on... 


-- 

pcarlini at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gdr at integrable-solutions
                   |                            |dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[pinskia at gcc dot gnu dot org]

------- Comment #19 from pinskia at gcc dot gnu dot org  2007-01-30 00:54 -------
(In reply to comment #18)
> Implementing the really trivial solution of providing what() members returning
> "std::bad_alloc", "std::bad_cast", "std::bad_typeid", and "std::bad_exception".
I don't think that is the correct solution as if you subclass these functions,
you get the incorrect result.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493

[Bug libstdc++/14493] std::bad_alloc::what() does not explain what happened

[pcarlini at suse dot de]

------- Comment #18 from pcarlini at suse dot de  2007-01-30 00:34 -------
Implementing the really trivial solution of providing what() members returning
"std::bad_alloc", "std::bad_cast", "std::bad_typeid", and "std::bad_exception".


-- 

pcarlini at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |pcarlini at suse dot de
                   |dot org                     |
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14493