[Bug c++/14365] New: gdb crashes when checking ctor of lambdas (in is_ctor_or_dtor)

[Bug c++/14365] New: gdb crashes when checking ctor of lambdas (in is_ctor_or_dtor)

[marco.trevisan at canonical dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14365

             Bug #: 14365
           Summary: gdb crashes when checking ctor of lambdas (in
                    is_ctor_or_dtor)
           Product: gdb
           Version: 7.4
            Status: NEW
          Severity: critical
          Priority: P2
         Component: c++
        AssignedTo: unassigned@sourceware.org
        ReportedBy: marco.trevisan@canonical.com
    Classification: Unclassified


Created attachment 6531
  --> http://sourceware.org/bugzilla/attachment.cgi?id=6531
gdb-fix-crash-when-checking-for-ctor-of-lambda by Thomas Voß

Using GDB to debug this test case: http://pastebin.ubuntu.com/1062024/ causes
it to crash in is_ctor_or_dtor.

Attached here patch by Thomas Voß that fixes it.

This is description:
«It turns out that gdb crashes as it tries to determine whether a field of a
lambda is a or ctor/dtor, given the fields name. Apparently, the field's name
is NULL and I added a check for that, bailing out and returning 0 ("no, this is
neither a dtor nor a ctor"). GDB behaves normally when being run on the test
program mentioned before. Patch is attached, generated with quilt.»

See launchpad bug http://pad.lv/1006860 for reference.

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[Bug c++/14365] gdb crashes when checking ctor of lambdas (in is_ctor_or_dtor)

[marco.trevisan at canonical dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14365

Marco Trevisan <marco.trevisan at canonical dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                URL|                            |https://bugs.launchpad.net/
                   |                            |ubuntu/+source/gdb/+bug/100
                   |                            |6860
                 CC|                            |marco.trevisan at canonical
                   |                            |dot com

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[Bug c++/14365] gdb crashes when checking ctor of lambdas (in is_ctor_or_dtor)

[jan.kratochvil at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14365

Jan Kratochvil <jan.kratochvil at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jan.kratochvil at redhat
                   |                            |dot com

--- Comment #1 from Jan Kratochvil <jan.kratochvil at redhat dot com> 2012-07-15 12:55:24 UTC ---
Please post any patches to gdb-patches at sourceware.org.

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[Bug c++/14365] gdb crashes when checking ctor of lambdas (in is_ctor_or_dtor)

[tromey at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14365

Tom Tromey <tromey at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at redhat dot com

--- Comment #2 from Tom Tromey <tromey at redhat dot com> 2012-08-01 18:55:14 UTC ---
I reproduced the bug.

I don't think this is the correct fix.

What seems to be happening here is that we are trying to
compute the physname for a type that is a pointer to a member
function of an unnamed structure type.
Because it is unnamed, c_type_print_base falls through to
printing the body of the structure, instead of its name.
This then crashes.

Maybe NULL checks in is_constructor_name and is_destructor_name
would be ok; though I am not sure.  But even if those were there
we would still be seeing very weird results here.

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[Bug c++/14365] gdb crashes when checking ctor of lambdas (in is_ctor_or_dtor)

[tromey at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14365

--- Comment #3 from Tom Tromey <tromey at redhat dot com> 2012-08-01 18:57:50 UTC ---
BTW I reproduced using the reported test case:

#include <sigc++/sigc++.h>

#if __cplusplus >= 201100L || defined (__GXX_EXPERIMENTAL_CXX0X__)
#include <type_traits>

namespace sigc
{
    template <typename Functor>
      struct functor_trait<Functor, false>
      {
        typedef decltype (::sigc::mem_fun(std::declval<Functor&>(),
&Functor::operator())) _intermediate;
        typedef typename _intermediate::result_type result_type;
        typedef Functor functor_type;
      };
}
#endif


int main()
{
  sigc::slot <bool> slot3 = [] () -> bool { return true; };
  sigc::slot <bool, int> slot4 = [] (int) -> bool { return true; };
  while (1);
}


and building it on Fedora 16 with

g++ -std=c++0x -g -o pr pr.cc $(pkg-config --cflags sigc++-2.0) $(pkg-config
--libs sigc++-2.0)

Simplest way to see it is "gdb -readnow pr"

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[Bug c++/14365] gdb crashes when checking ctor of lambdas (in is_ctor_or_dtor)

[keiths at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14365

Keith Seitz <keiths at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |keiths at redhat dot com

--- Comment #4 from Keith Seitz <keiths at redhat dot com> 2012-08-03 17:22:08 UTC ---
I think Tom is correct. IMO the questionable thing done here is asking
c_type_print_base to print details of the type when we have a pointer
member/method whose containing class/struct is anonymous (TYPE_NAME (type) ==
NULL). That just doesn't seem right.

I believe the proper fix is simply for c_type_print_varspec_prefix to honor the
SHOW parameter when it is calling other c_type_print_* functions.

In this function, the only cases which do not pass SHOW to the other type
printing functions are MEMBERPTR and METHODPTR, exactly where we are seeing
problems.

I'm working on a test case for this now, and will submit a patch when it is
finished. [It requires hand-written DWARF.]

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[Bug c++/14365] gdb crashes when checking ctor of lambdas (in is_ctor_or_dtor)

[cvs-commit at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=14365

--- Comment #5 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> 2012-08-19 19:37:57 UTC ---
CVSROOT:    /cvs/src
Module name:    src
Changes by:    kseitz@sourceware.org    2012-08-19 19:37:51

Modified files:
    gdb            : ChangeLog c-typeprint.c 
    gdb/testsuite  : ChangeLog 
Added files:
    gdb/testsuite/gdb.dwarf2: dw2-anon-mptr.exp dw2-anon-mptr.S 

Log message:
    PR c++/14365
    * c-typeprint.c (c_type_print_varspec_prefix): Pass
    -1 for SHOW to c_type_print_base for METHODPTR and MEMBERPTR.

    * gdb.dwarf2/dw2-anon-mptr.exp: New file.
    * gdb.dwarf2/dw2-anon-mptr.S: New file.

Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/ChangeLog.diff?cvsroot=src&r1=1.14602&r2=1.14603
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/c-typeprint.c.diff?cvsroot=src&r1=1.75&r2=1.76
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/testsuite/ChangeLog.diff?cvsroot=src&r1=1.3343&r2=1.3344
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/testsuite/gdb.dwarf2/dw2-anon-mptr.exp.diff?cvsroot=src&r1=NONE&r2=1.1
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/testsuite/gdb.dwarf2/dw2-anon-mptr.S.diff?cvsroot=src&r1=NONE&r2=1.1

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[Bug c++/14365] gdb crashes when checking ctor of lambdas (in is_ctor_or_dtor)

[keiths at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14365

Keith Seitz <keiths at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
         AssignedTo|unassigned at sourceware    |keiths at redhat dot com
                   |dot org                     |
   Target Milestone|---                         |7.6

--- Comment #6 from Keith Seitz <keiths at redhat dot com> 2012-08-19 19:40:00 UTC ---
I have committed a patch to fix this. If there are any further problems, please
let me know.

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