CODEWITHSUNDEEP
c++gcc
Jerry Oberle
Jerry Oberle

Reputation: 194

How can I find all places a given member function or ctor is called in g++ code?

I am trying to find all places in a large and old code base where certain constructors or functions are called. Specifically, these are certain constructors and member functions in the std::string class (that is, basic_string<char>). For example, suppose there is a line of code:

std::string foo(fiddle->faddle(k, 9).snark);

In this example, it is not obvious looking at this that snark may be a char *, which is what I'm interested in.

Attempts To Solve This So Far

I've looked into some of the dump features of gcc, and generated some of them, but I haven't been able to find any that tell me that the given line of code will generate a call to the string constructor taking a const char *. I've also compiled some code with -s to save the generated equivalent assembly code. But this suffers from two things: the function names are "mangled," so it's impossible to know what is being called in C++ terms; and there are no line numbers of any sort, so even finding the equivalent place in the source file would be tough.

Motivation and Background

In my project, we're porting a large, old code base from HP-UX (and their aCC C++ compiler) to RedHat Linux and gcc/g++ v.4.8.5. The HP tool chain allowed one to initialize a string with a NULL pointer, treating it as an empty string. The Gnu tools' generated code fails with some flavor of a null dereference error. So we need to find all of the potential cases of this, and remedy them. (For example, by adding code to check for NULL and using a pointer to a "" string instead.)

So if anyone out there has had to deal with the base problem and can offer other suggestions, those, too, would be welcomed.

Upvotes: 6

Views: 139

Answers (2)

Alexander Oh
Alexander Oh

Reputation: 25631

Have you considered using static analysis?

Clang has one called clang analyzer that is extensible.

You can write a custom plugin that checks for this particular behavior by implementing a clang ast visitor that looks for string variable declarations and checks for setting it to null.

There is a manual for that here.

See also: https://github.com/facebook/facebook-clang-plugins/blob/master/analyzer/DanglingDelegateFactFinder.cpp

Upvotes: 1

Bediver
Bediver

Reputation: 782

First I'd create a header like this:

#include <string>

class dbg_string : public std::string {
public:
    using std::string::string;
    dbg_string(const char*) = delete;
};

#define string dbg_string

Then modify your makefile and add "-include dbg_string.h" to cflags to force include on each source file without modification.

You could also check how is NULL defined on your platform and add specific overload for it (eg. dbg_string(int)).

Upvotes: 0

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