<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - LLDB Not Stepping into Multiple Inheritance Virtual Functions"
href="https://bugs.llvm.org/show_bug.cgi?id=44068">44068</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>LLDB Not Stepping into Multiple Inheritance Virtual Functions
</td>
</tr>
<tr>
<th>Product</th>
<td>lldb
</td>
</tr>
<tr>
<th>Version</th>
<td>9.0
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>All Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>lldb-dev@lists.llvm.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>acwilson96@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>jdevlieghere@apple.com, llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=22842" name="attach_22842" title="Reproducer program.">attachment 22842</a> <a href="attachment.cgi?id=22842&action=edit" title="Reproducer program.">[details]</a></span>
Reproducer program.
Overview:
Using LLDB to debug polymorphic objects that have multiple inheritance will not
step into virtual functions.
Steps to Reproduce:
```
$ clang++ -std=c++11 -g -O0 reproducer.cpp -o clang.out
$ lldb clang.out
(lldb) target create "clang.out"
Current executable set to 'clang.out' (x86_64).
(lldb) b 36
Breakpoint 1: where = clang.out`main + 103 at
reproducer.cpp:36:16, address = 0x0000000000400d67
(lldb) r
Process 2764 launched: '/home/rdtscp/Documents/lldb_reproducer/clang.out'
(x86_64)
Process 2764 stopped
* thread #1, name = 'clang.out', stop reason = breakpoint 1.1
frame #0: 0x0000000000400d67 clang.out`main(argc=1,
argv=0x00007fffffffe808) at reproducer.cpp:36:16
33 int main(int argc, char **argv) {
34 using namespace Test;
35 std::shared_ptr<Interface> object = std::shared_ptr<Concrete>(new
Concrete());
-> 36 int output = object->vFun();
37 std::cout << output << std::endl;
38 return output;
39 }
(lldb) s
Process 2764 stopped
* thread #1, name = 'clang.out', stop reason = step in
frame #0: 0x0000000000400d86 clang.out`main(argc=1,
argv=0x00007fffffffe808) at reproducer.cpp:37:16
34 using namespace Test;
35 std::shared_ptr<Interface> object = std::shared_ptr<Concrete>(new
Concrete());
36 int output = object->vFun();
-> 37 std::cout << output << std::endl;
38 return output;
39 }
(lldb)
```
Altering the `Concrete` class to be:
```
class Concrete : // public Base,
public Interface {
public:
virtual int vFun() override {
volatile int x = rand();
if (x > 0)
return x;
else
return 0;
}
};
```
Will result in:
```
$ clang++ -std=c++11 -g -O0 reproducer.cpp -o clang.out
$ lldb clang.out
(lldb) target create "clang.out"
Current executable set to 'clang.out' (x86_64).
(lldb) b 36
Breakpoint 1: where = clang.out`main + 104 at reproducer.cpp:36:16, address =
0x0000000000400cf8
(lldb) r
Process 2869 launched: '/home/rdtscp/Documents/lldb_reproducer/clang.out'
(x86_64)
Process 2869 stopped
* thread #1, name = 'clang.out', stop reason = breakpoint 1.1
frame #0: 0x0000000000400cf8 clang.out`main(argc=1,
argv=0x00007fffffffe808) at reproducer.cpp:36:16
33 int main(int argc, char **argv) {
34 using namespace Test;
35 std::shared_ptr<Interface> object = std::shared_ptr<Concrete>(new
Concrete());
-> 36 int output = object->vFun();
37 std::cout << output << std::endl;
38 return output;
39 }
(lldb) s
Process 2869 stopped
* thread #1, name = 'clang.out', stop reason = step in
frame #0: 0x0000000000400fec
clang.out`Test::Concrete::vFun(this=0x0000000000615c20) at reproducer.cpp:23:24
20 public Interface {
21 public:
22 virtual int vFun() override {
-> 23 volatile int x = rand();
24 if (x > 0)
25 return x;
26 else
(lldb)
```
The above shows that making the `Concrete` class inherit from the `Base` class
prevents us from stepping into `vFun()`.
System Settings:
```
OS: Debian GNU/Linux 9.11 (stretch) x86_64
Model: VirtualBox 1.2
Kernel: 4.9.0-11-amd64
Uptime: 1 hour, 3 minutes
Packages: 1722
Shell: zsh 5.3.1
CPU: Intel i5-7360U (1) @ 2.3GHz
GPU: VMware SVGA II Adapter
Memory: 219MB / 996MB
```
```
$ clang++ --version
clang version 9.0.0-svn364966-1~exp1+0~20190702204433.1332~1.gbpb44072 (trunk)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
$ lldb --version
lldb version 9.0.0
```
Additional Information:
I tried using:
```
g++ (Debian 6.3.0-18+deb9u1) 6.3.0 20170516
GNU gdb (Debian 7.12-6) 7.12.0.20161007-git
```
To see if my code was incorrect, but g++ and gdb were able to step into
"vFun()" fun.</pre>
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