[Bug gdb/18584] New: "Duplicate variable object name" using pretty-printing when variable not initialized

[Bug gdb/18584] New: "Duplicate variable object name" using pretty-printing when variable not initialized

[marc.khouzam at ericsson dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18584

            Bug ID: 18584
           Summary: "Duplicate variable object name" using pretty-printing
                    when variable not initialized
           Product: gdb
           Version: 7.9
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: marc.khouzam at ericsson dot com
  Target Milestone: ---

A bug was opened on CDT (http://eclip.se/470761) about GDB reporting "Duplicate
variable object name" when trying to inspect a vector using pretty-printing.

163-var-update 1 var1
163^error,msg="Duplicate variable object name"

What seems to happen is that the variable object is created for a vector that
has not been initialized yet, but after the initialization of the vector, it
seems too late and GDB does not recover when trying to update the variable.

Below is a session to reproduce the problem.  Note that the program used needs
to be compiled with -std=c++11:


> gdb.master a.out
GNU gdb (GDB) 7.9.50.20150623-cvs
(gdb) source /home/lmckhou/prettyPrint/gdbinit 
(gdb) l
1       #include <vector>
2       #include <memory>
3
4       using namespace std;
5
6       struct Test {
7           int x;
8           int y;
9       };
10
11      int main() {
12          vector<shared_ptr<Test>> v;
13
14          v.push_back(make_shared<Test>());
15          v.push_back(make_shared<Test>());
16
17          auto v2 = v;
18
19          for (size_t i = 0; i < v.size(); i++)
20              v[i]->x = i;
21
22          return 0;
23      }

(gdb) interpreter-exec mi -enable-pretty-printing
^done

(gdb) start
Temporary breakpoint 1 at 0x400ba9: file test.cc, line 12.
Starting program: /home/lmckhou/testing/a.out 

Temporary breakpoint 1, main () at test.cc:12
12          vector<shared_ptr<Test>> v;

(gdb) interpreter-exec mi "-var-create - * v2"
^done,name="var1",numchild="0",value="{...}",type="std::vector<std::shared_ptr<Test>,
std::allocator<std::shared_ptr<Test> >
>",thread-id="1",displayhint="array",dynamic="1",has_more="1"

(gdb) interpreter-exec mi "-var-list-children var1"
^error,msg="Cannot access memory at address 0x0"

(gdb) until 22
main () at test.cc:22
22          return 0;

(gdb) interpreter-exec mi "-var-update var1"
^error,msg="Duplicate variable object name

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[Bug gdb/18584] "Duplicate variable object name" using pretty-printing when variable not initialized

[marc.khouzam at ericsson dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18584

Marc Khouzam <marc.khouzam at ericsson dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |simon.marchi at ericsson dot com

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[Bug gdb/18584] "Duplicate variable object name" using pretty-printing when variable not initialized

[xhpohanka at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18584

Jan Pohanka <xhpohanka at gmail dot com> changed:

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

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[Bug gdb/18584] "Duplicate variable object name" using pretty-printing when variable not initialized

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18584

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Blocks|                            |32726
                 CC|                            |tromey at sourceware dot org


Referenced Bugs:

https://sourceware.org/bugzilla/show_bug.cgi?id=32726
[Bug 32726] [meta] Pretty printing
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[Bug gdb/18584] "Duplicate variable object name" using pretty-printing when variable not initialized

[daniel.knezevic at htecgroup dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18584

Daniel Knezevic <daniel.knezevic at htecgroup dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |daniel.knezevic at htecgroup dot c
                   |                            |om

--- Comment #1 from Daniel Knezevic <daniel.knezevic at htecgroup dot com> ---
I tried to reproduce this issue with the latest master with no success. It
seems like this is no longer an issue and the bug can be closed.

Here is the output from the reported program:

GNU gdb (GDB) 18.0.50.20251023-git
Copyright (C) 2025 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-pc-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.out...
(gdb) l
6       struct Test {
7         int x;
8         int y;
9       };
10      
11      int main() {
12        vector<shared_ptr<Test>> v;
13      
14        v.push_back(make_shared<Test>());
15        v.push_back(make_shared<Test>());
(gdb) 
16      
17        auto v2 = v;
18      
19        for (size_t i = 0; i < v.size(); i++)
20            v[i]->x = i;
21        
22        return 0;
23      }
(gdb) 
❌️ End of the file was already reached, use "list ." to list the current
location again
(gdb) interpreter-exec mi -enable-pretty-printing
^done
(gdb) start
Temporary breakpoint 1 at 0x1296: file test.cpp, line 11.
Starting program: /home/dknezevic/work/duplicateVarName/a.out 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Temporary breakpoint 1, main () at test.cpp:11
11      int main() {
(gdb) interpreter-exec mi "-var-create - * v2"
^done,name="var1",numchild="1",value="{...}",type="std::vector<std::shared_ptr<Test>,
std::allocator<std::shared_ptr<Test> > >",thread-id="1",has_more="0"
(gdb) interpreter-exec mi "-var-list-children var1"
^done,numchild="1",children=[child={name="var1.std::_Vector_base<std::shared_ptr<Test>,
std::allocator<std::shared_ptr<Test> >
>",exp="std::_Vector_base<std::shared_ptr<Test>,
std::allocator<std::shared_ptr<Test> >
>",numchild="1",type="std::_Vector_base<std::shared_ptr<Test>,
std::allocator<std::shared_ptr<Test> > >",thread-id="1"}],has_more="0"
(gdb) until 22
main () at test.cpp:22
22        return 0;
(gdb) interpreter-exec mi "-var-update var1"
^done,changelist=[]
(gdb)

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