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From: "simon.marchi at ericsson dot com" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug gdb/17416] New: -var-list-children fails with "set print object
 on" and invalid/NULL value
Date: Fri, 19 Sep 2014 21:24:00 -0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=17416

            Bug ID: 17416
           Summary: -var-list-children fails with "set print object on"
                    and invalid/NULL value
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: simon.marchi at ericsson dot com

Created attachment 7796
  --> https://sourceware.org/bugzilla/attachment.cgi?id=7796&action=edit
Test program

When

- "set print object" is on
- The variable object is a pointer to a struct, and it contains an invalid
value (e.g. NULL, or random uninitialized value)
- The variable object (struct) has a child which is also a pointer to a struct.

-var-list-children returns an error. GDB tries to dereference the top-level
pointer to get the value of the child one, in order to go determine the real
type of the pointed object using RTTI. In the process, value_ind in
value_rtti_indirect_type throws an error that is never caught.

What happens then is that the variable object for the child is half-created. If
the top-level pointer is set to a sensible value and we try to do
-var-list-children again, we get a "Duplicate variable object name" error.

The attached test case shows the problem.

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