Getting the "description" of a variable

[Siva Chandra <sivachandra@google.com>]

Hello,

As with most of my questions, I am really not sure if the subject line
is good/apt for my question. The question is, "how can I get the
description of a variable from the GDB command line?"

By description, I mean this:
1. File and line it is declared at.
2. Its type and scope.

I think GDB already has ways to get this information using multiple commands.

My use case can be illustrated with an example. Consider the following
C++ snippet.

class Counter
{
public:
  int inc();

  int count;
};

int
Counter::inc ()
{
  count++;
  return count;
}

class A
{
public:
  int inc();

  static Counter counter;
};

Counter A::counter;

int
A::inc ()
{
  counter.inc(); // Break here
}

int
main ()
{
  A a;

  a.inc();

  return 0;
}

Lets say I am new to this code and single stepping through it and
currently stopped at the line marked with "Break here". I now want to
know what this variable "counter" is. I print its value, and print its
type. If I do "info variables counter", one of the results is
"A::counter" and I realize that it is a static member of class A.
Next, I can use gdb.lookup_symbol('A::counter') to get to the filename
and line number where it is declared. There are a few problems I face
when I use this kind of workflow:

1. Too many steps to get to what I want. If I am interrupted, I loose
track of where I am and will have to start from the beginning all
over.
2. gdb.lookup_symbol('counter') returns (None, True). I have to use
gdb.lookup_symbol('A::counter').
3. The filename and line number I get via gdb.lookup_symbol is mostly
likely the location where the static member is declared out of the
class in a *.cc file. This is not good enough because the comments
describing this member are typically found in a *.h file where the
class is defined. So, I will need another step via
gdb.lookup_symbol('A') to get to the line and file where the class A
is defined.

Is there a shorter workflow to get the same information already existing in GDB?

If not:

1. Is it OK to add more info to 'struct symbol' to store all the files
and lines where a "symbol" is declared. If not 'struct symbol', is
there a better place where such info can be added?
2. If #1 is OK, then, can we add a command 'describe' using GDB Python
which prints the info I am looking for?

Thanks,
Siva Chandra