Display smart pointers in eclipse cdt using gdb pretty printers

Question

When I debug my c++11 application, I want to see the objects unique_ptr and shared_ptr are pointing to. But using libstdc++ pretty printers, only a string with address and similar stuff is printed, but I can't expand it to view its content. I already tried the following workaround but I did not work for me:

https://sourceware.org/ml/gdb/2013-04/msg00042.html

Can anybody help me with that. Actually I think this might be a pretty basic problem, so I'm wondering wether there is no way to do so. But searching the internet I couldn't find any hint...

Answer 1

Following your link, I did exactly what Michael described, and it works fine. Probably, you did some mistake in applying the changes. The libstdcxx/v6/printers.py should now have in lines 103 - 174:

class SharedPointerPrinter:
    "Print a shared_ptr or weak_ptr"

    class _iterator:
        def __init__(self, sharedPointer):
            self.sharedPointer = sharedPointer
            self.managedValue = sharedPointer.val['_M_ptr']
            self.count = 0

        def __iter__(self):
            return self

        def next(self):
            if self.managedValue == 0:
                raise StopIteration
            self.count = self.count + 1
            if (self.count == 1):
                return ('Use count', self.sharedPointer.val['_M_refcount']['_M_pi']['_M_use_count'])
            elif (self.count == 2):
                return ('Weak count', self.sharedPointer.val['_M_refcount']['_M_pi']['_M_weak_count'] - 1)
            elif (self.count == 3):
                return ('Managed value', self.managedValue)
            else:
                raise StopIteration

    def __init__ (self, typename, val):
        self.typename = typename
        self.val = val

    def children (self):
        return self._iterator(self)

    def to_string (self):
        state = 'empty'
        refcounts = self.val['_M_refcount']['_M_pi']
        if refcounts != 0:
            usecount = refcounts['_M_use_count']
            weakcount = refcounts['_M_weak_count']
            if usecount == 0:
                state = 'expired, weakcount %d' % weakcount
            else:
                state = 'usecount %d, weakcount %d' % (usecount, weakcount - 1)
        return '%s (%s) to %s' % (self.typename, state, self.val['_M_ptr'])

class UniquePointerPrinter:
    "Print a unique_ptr"

    class _iterator:
        def __init__(self, uniquePointer):
            self.uniquePointer = uniquePointer
            self.managedValue = uniquePointer.val['_M_t']['_M_head_impl']
            self.count = 0

        def __iter__(self):
            return self

        def next(self):
            if self.managedValue == 0 or self.count == 1:
                raise StopIteration
            self.count = self.count + 1
            return ('Managed value', self.managedValue)

    def __init__ (self, typename, val):
        self.val = val

    def children (self):
        return self._iterator(self)

    def to_string (self):
        v = self.val['_M_t']['_M_head_impl']
        return ('std::unique_ptr<%s> containing %s' % (str(v.type.target()),
                                                       str(v)))

Kind regards