How to Debug C++11 Code with Unique_Ptr in Ddd (Or Gdb)

How to debug C++11 code with unique_ptr in DDD (or gdb)?

This problem is actually not related to C++11, unique_ptr or pretty printing. The problem is that gcc does not emit code for std::unique_ptr::operator* that could be called by gdb to dereference the unique_ptr. If you for instance add *pTest; to your code then gdb does perform the dereferencing.

A similar problem is described in the SO post How to `print`/evaluate c++ template functions in gdb. Almost the same problem is described for an auto_ptr at https://sourceware.org/ml/archer/2012-q1/msg00003.html. If I understand the thread correctly one workaround would be to patch the pretty printer and also print out the dereferenced pointer when printing the unique_ptr. A gdb bug report can be found at http://sourceware.org/bugzilla/show_bug.cgi?id=12937.

The gdb wiki at https://sourceware.org/gdb/wiki/STLSupport describes more pretty printing solutions, which could have other workarounds.

Edit: A more elegant solution forcing the compiler to emit code for all member templates including operator* is to explicitly instantiate the class:

template class std::unique_ptr<MyType>;

Debugging mapint, unique_ptrA in gdb

I could debug map and vector without using gdb 7, but with pretty printer setup.

This site(http://www.yolinux.com/TUTORIALS/GDB-Commands.html#STLDEREF) has the procedure. In short.

1. Copy the .gdbinit in ~/
2. Restart the gdb
3. Use pvector for printing vectors.

Please refer to this page: https://stackoverflow.com/a/17246292/260127
And this page: How to print out the content in vector<unique_ptr> with gdb on Mac OS X

How to print out the content in vectorunique_ptr with gdb on Mac OS X

I could use Xcode; lldb works fine on Xcode.

How to view the internal data of a smart pointer inside gdb?

Try the following:

p *si._M_ptr

Now, this assumes that you're using libstdc++.so, given the output for p si.

Alternatively, you could use the value 0x614c20 directly (from your output):

p {int}0x614c20

Both should display the value 5.

How to access target of std::tr1::shared_ptr in GDB

Try with

(gdb) p (*sharedPtr.get())

that function returns the a pointer to the object owned by the smart pointer.

---

Related Topics