[Bug c++/15154] New: Non-POD class causes garbage when printing object from a return value

[Bug c++/15154] New: Non-POD class causes garbage when printing object from a return value

[mstensho at opera dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15154

             Bug #: 15154
           Summary: Non-POD class causes garbage when printing object from
                    a return value
           Product: gdb
           Version: 7.5
            Status: NEW
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned@sourceware.org
        ReportedBy: mstensho@opera.com
    Classification: Unclassified


Created attachment 6874
  --> http://sourceware.org/bugzilla/attachment.cgi?id=6874
Test case

It seems impossible to print non-POD object values from return values
correctly. Also happens with "print function()" when function() returns
something non-POD. That even crashes sometimes.

See attachment. Works fine if PREVENT_NONPOD is defined.

This is with gdb 7.4.1-debian , but it also fails when building 7.5 on my own.

Full output from gdb --version:
GNU gdb (GDB) 7.4.1-debian
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.

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[Bug c++/15154] Non-POD class causes garbage when printing object from a return value

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=15154

--- Comment #1 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
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the project "gdb and binutils".

The branch, master has been updated
       via  ebb8ece2ef50ba3f86e8b4ab7a22a4c7734d114b (commit)
       via  2d1c107c1b8835f4e85c35320d8595a4a6fcaebe (commit)
       via  82c48ac732edb0155288a93ef3dd39625ff2d2e1 (commit)
       via  778811d5e7eb96b5ecb848033ffaa2df455a921e (commit)
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- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ebb8ece2ef50ba3f86e8b4ab7a22a4c7734d114b

commit ebb8ece2ef50ba3f86e8b4ab7a22a4c7734d114b
Author: Siva Chandra <sivachandra@chromium.org>
Date:   Tue Sep 9 06:50:26 2014 -0700

    Fix gnuv3_pass_by_reference to treat dynamic classes as non-trivial.

    gdb/ChangeLog:

        * gnu-v3-abi.c (gnuv3_pass_by_reference): Treat dynamic classes
        as non-trivial.

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=2d1c107c1b8835f4e85c35320d8595a4a6fcaebe

commit 2d1c107c1b8835f4e85c35320d8595a4a6fcaebe
Author: Siva Chandra <sivachandra@chromium.org>
Date:   Tue Sep 9 06:46:14 2014 -0700

    Add new non-trial return value tests.

    gdb/testsuite/ChangeLog:

        * gdb.cp/non-trivial-retval.cc: Add new test cases.
        * gdb.cp/non-trivial-retval.exp: Add new tests.

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=82c48ac732edb0155288a93ef3dd39625ff2d2e1

commit 82c48ac732edb0155288a93ef3dd39625ff2d2e1
Author: Siva Chandra <sivachandra@chromium.org>
Date:   Tue Sep 9 06:03:42 2014 -0700

    Fix gnuv3_pass_by_reference to lookup copy c-tors with qualified args.

    Before this, a copy constructor declared as in the following snippet was
    not being treated as a copy constructor.

    class A
    {
    public:
      A (A &); // OK.
      A (const A &); // Not being treated as a copy constructor because of the
                     // 'const' qualifier.
    };

    gdb/ChangeLog:

        PR c++/13403
        PR c++/15154
        * gnu-v3-abi.c (gnuv3_pass_by_reference): Lookup copy constructors
        with qualified args.

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=778811d5e7eb96b5ecb848033ffaa2df455a921e

commit 778811d5e7eb96b5ecb848033ffaa2df455a921e
Author: Siva Chandra <sivachandra@chromium.org>
Date:   Mon Sep 8 07:04:59 2014 -0700

    Non trivial return value tests.

    gdb/testsuite/ChangeLog:

        PR c++/13403
        PR c++/15154
        * gdb.cp/non-trivial-retval.cc: New file.
        * gdb.cp/non-trivial-retval.exp: New file.

-----------------------------------------------------------------------

Summary of changes:
 gdb/ChangeLog                               |   12 +++
 gdb/gnu-v3-abi.c                            |   21 ++++-
 gdb/testsuite/ChangeLog                     |   12 +++
 gdb/testsuite/gdb.cp/non-trivial-retval.cc  |  119 +++++++++++++++++++++++++++
 gdb/testsuite/gdb.cp/non-trivial-retval.exp |   36 ++++++++
 5 files changed, 195 insertions(+), 5 deletions(-)
 create mode 100644 gdb/testsuite/gdb.cp/non-trivial-retval.cc
 create mode 100644 gdb/testsuite/gdb.cp/non-trivial-retval.exp

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[Bug c++/15154] Non-POD class causes garbage when printing object from a return value

[naesten at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=15154

Samuel Bronson <naesten at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |naesten at gmail dot com
   Attachment #6874|application/octet-stream    |text/plain
          mime type|                            |

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[Bug c++/15154] Non-POD class causes garbage when printing object from a return value

[naesten at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=15154

--- Comment #2 from Samuel Bronson <naesten at gmail dot com> ---
Still doesn't DTRT with, say, std::list<std::string> and pretty printers; see
https://bugs.debian.org/776893 for an example: it seems to copy the object
byte-by-byte to some other location and print that one, with the result that
the printer goes around the list over and over and over and over because it can
never find the link-to-header it expects to indicate the end of the list.

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[Bug c++/15154] Non-POD class causes garbage when printing object from a return value

[naesten at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=15154

Samuel Bronson <naesten at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |http://bugs.debian.org/7768
                   |                            |93

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[Bug c++/15154] Non-POD class causes garbage when printing object from a return value

[sivachandra at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=15154

Siva Chandra <sivachandra at gmail dot com> changed:

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

--- Comment #3 from Siva Chandra <sivachandra at gmail dot com> ---
(In reply to Samuel Bronson from comment #2)
> Still doesn't DTRT with, say, std::list<std::string> and pretty printers;
> see https://bugs.debian.org/776893 for an example: it seems to copy the
> object byte-by-byte to some other location and print that one, with the
> result that the printer goes around the list over and over and over and over
> because it can never find the link-to-header it expects to indicate the end
> of the list.

I do not think the original problem in this PR and the above are related. I
think a new/different bug would be good.

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