CODEWITHSUNDEEP
c++functiondebuggingsignaturetrace
Makogan
Makogan

Reputation: 9622

Search for function with specific signature call?

Assume I have some C++ functions:

void A(int i) {
/* some code */
}

void A(string s) {
/* some code */
}

void A(string s, int i) {
/* some code */
}

Assume the first call makes 80% of the A() calls, the second makes 15% and the last makes 5%.

I want to static trace the calls. If I am interested in in the first kind of call, no problem, most of the string search results of "A(" will be of type 1, but if I ONLY want type 2 or type 3, I will have a lot of unneeded noise from type 1.

For type 3, regular expressions can help if I look for a following string that has exactly 2 comas between parenthesis A(*,*,*) (I don't actually know the programming syntax for RE)

But for type 2 this won't work.

Is there any technique I can use to find a function call by its signature?

Edit: What I mean by "trace" is understanding the current codebase by finding all the call points of the needed function.

Upvotes: 1

Views: 279

Answers (1)

πάντα ῥεῖ
πάντα ῥεῖ

Reputation: 1

For type 3, regular expressions can help if I look for a following string that has exactly 2 comas between parenthesis A(,,*) (I don't actually know the programming syntax for RE)

But for type 2 this won't work.

Is there any technique I can use to find a function call by its signature?

Well besides you search your files using some regex (with e.g. Notepad++ file search, egrep or similar), and assuming that you're able to change the source code where these functions are declared / defined, you may use some compiler standard feature like the [[deprecated]] attribute:

   void A(int i) {
   /* some code */
   }

   [[deprecated]] void A(string s) {
// ^^^^^^^^^^^^^^
   /* some code */
   }

   [[deprecated]] void A(string s, int i) {
// ^^^^^^^^^^^^^^
   /* some code */
   }

This will show you warnings when these functions are used:

int main() {
    A(5);
    A("Hello");
    A("Hello",42);
}

main.cpp:9:25: note: declared here
     [[deprecated]] void A(string s) {
                         ^
main.cpp:20:18: warning: 'void A(std::__cxx11::string)' is deprecated [-Wdeprecated-declarations]
         A("Hello");
                  ^
main.cpp:9:25: note: declared here
     [[deprecated]] void A(string s) {
                         ^
main.cpp:21:21: warning: 'void A(std::__cxx11::string, int)' is deprecated [-Wdeprecated-declarations]
         A("Hello",42);
                     ^
main.cpp:13:25: note: declared here
     [[deprecated]] void A(string s, int i) {
                         ^
main.cpp:21:21: warning: 'void A(std::__cxx11::string, int)' is deprecated [-Wdeprecated-declarations]
         A("Hello",42);
                     ^
main.cpp:13:25: note: declared here
     [[deprecated]] void A(string s, int i) {
                         ^

See an online example compiled with g++.

You can even decorate that with a message for your coworkers maintaining the code base:

   [[deprecated("Get rid of these performance killing calls."
                " Use A(A::getPrecomputedHash(s)) instead.")]] 
      void A(string s) {
      }

Upvotes: 2

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