How to search for function calls, not just function definitions, with etags?

Question

Edit: Answered my own question.

In the past, when working with Emacs, C and etags, I was able to do M-. and find a function definition. But I could also do M-, and find all calls of that function. Very convenient.

I've recently started programming C with Emacs again. I've built a TAGS file with etags. I can use M-. but I can't use M-,. When I look into the TAGS file, I see that there are only lines for the function definitions. There is no information where all the calls to that function are.

So my suspicion is that I should build the TAGS file differently. But I've read the man-page for etags, and I can't find any options that might do what I want.

The only thing I could imagine is that the company where I worked in the past had a modified version of etags?

We had a coding convention that function-calls should always have a space between name and open-bracket. E.g. int my_function (int x){ and calls should never have a space there. E.g. x = my_function(1);. Could this be it ? Or is that unrelated ?

Answer 1

I think I found the answer to my own question.
We were probably using GNU's idutils.
http://www.gnu.org/software/idutils/manual/idutils.html

This package allows you to use mkid to make an ID file, just like etags makes a TAGS file. Then you can use the gid utility to search for functions. All I now need to do is install mkid and gid, and try to remember how I can integrate the gid command in Emacs.

I hope this question might be useful in the future for others.