Hello there,
hope you are all doing well.
While working with libdwarf/dwarfdump, I noticed the following behavior.
Suppose we have the following code:
```C++
#ifndef CCHANNEL_HPP_
#define CCHANNEL_HPP_
class CChannel
{
public:
typedef enum
{
UNUSED = 0,
INACTIVE = 1,
ACTIVE = 2,
} TState;
typedef struct
{
TState State;
int data;
} SHK;
CChannel();
virtual void getData();
~CChannel();
private:
SHK Hk;
};
#endif /* CCHANNEL_HPP_ */
```
It seems that if there is a virtual method inside of a class, the DWARF
outputs `SHK` struct as an anonymous struct. This means that an
instantiation of SHK will show a structure with all the info, except the
name itself("SHK" in this case).
Interestingly enough if the struct declaration is written as the
following, it does not treat it as a an anonymous struct:
```C++
typedef struct SHK
{
TState State;
int data;
} SHK;
```
Assuming this is how it is used:
```C++
#ifndef VC_MSGS_H
#define VC_MSGS_H
#include "cchannel.hpp"
#ifdef __cplusplus
extern "C" {
#endif
typedef struct
{
int data;
CChannel::SHK Channel[1];
} HkTlm_t;
#ifdef __cplusplus
}
#endif
#endif /* VC_MSG_H */
```
It also does not happen if `Channel` is just a member instead of an
array (even if there is a virtual method in CChannel):
```C++
#ifndef VC_MSGS_H
#define VC_MSGS_H
#include "cchannel.hpp"
#ifdef __cplusplus
extern "C" {
#endif
typedef struct
{
int data;
CChannel::SHK Channel;
} HkTlm_t;
#ifdef __cplusplus
}
#endif
#endif /* VC_MSG_H */
```
I'm just looking for some clarification to make sure I understand what
is going on here and not going down the wrong path....
Here is some info about my machine
gcc (Ubuntu 9.4.0-1ubuntu1~20.04.2) 9.4.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
NAME="Pop!_OS"
VERSION="20.04 LTS"
ID=pop
ID_LIKE="ubuntu debian"
PRETTY_NAME="Pop!_OS 20.04 LTS"
VERSION_ID="20.04"
HOME_URL="https://pop.system76.com";
SUPPORT_URL="https://support.system76.com";
BUG_REPORT_URL="https://github.com/pop-os/pop/issues";
PRIVACY_POLICY_URL="https://system76.com/privacy";
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal
LOGO=distributor-logo-pop-os
Hope I was clear enough about my report. I know it's a bit all over the
place, but my main concern is making sure /when//under what
circumstances will gcc link the variable to the anonymous struct
instead of typedef so I can document a tool I work on that relies on
libdwarf correctly.
Thanks in advance
Lorenzo
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