Sensible debugging in Eclipse of STL containers - c++

I am confused as to how is one supposed to debug STL containers in eclipse. The Variables window just shows the container internal variables, not the collection of objects, that I am storing in it. From there, I can only expand m_start pointer to see the first element. And that's it.
Currently, I am solving this problem by accessing gdb directly from the console: p myvect[0]#10 will print the first 10 elements of a vector.
There is this article, urging students in some university to download some python script. My issues with the article are 1) My Eclipse Luna lacks the exact menus they explain about 2) this sentence: "According to its official documentations, there exists a unresolved bug and you should revise it by yourself in the source file."
I heard Visul Studio presents something called "Raw view".
To me, it sounds quite simple and very important to have built-in STL container debugging capabilities for Eclipse CDT. Do they exist? If no, why were they not implemented?

You don't mention your platform.
On "recent" (at least the last couple of years, probably longer) Linux distros, everything is set up to "just work". Of course there's a lot of machinery backing this, and all the bits must be in place:
Your gdb must be Python-enabled
The pretty-printers for libstdc++ must be installed in a way that causes them to automatically activate when debugging
Your Eclipse must tell gdb that it understands pretty-printing
As I said, in a recent environment all of this works. You can try it out by hand using gdb in the terminal and printing some STL data structure; even just a string will do. If you get incomprehensible goo, then something isn't set up properly.
If you aren't on a Linux distro you can try to set this stuff up by hand. It's a bit more involved to do so, but there are some instructions on the gdb wiki that are reasonable enough.

Related

Tracking c/c++ data structure sizes

I am trying to find a tool that can show me information about all the data structures in a program. I want to know when certain data structures were accessed and how their sizes changed throughout the course of the program. For example I want the tool to know that all the nodes in a linked list belong to one single data structure. Does a tool like this exist? I couldn't seem to find one through googling. Thanks
Some Toolchain, for example, Xcode's Toolchain, provides debugging features, which allows you to keep track of the memory use, CPU times and network using. The tracking data structure in memory could be achieved if you set breakpoint in the program. Without breakpoint, it's not likely to track the change of data structure since the CPU usually runs pretty fast. What you need is a good IDE with debugging, profiling ...
My first question is: what's your compiler? One person mentioned gdb as a useful tool, but that's only the case if you're using gcc/g++. Xcode has its own compiler/debugger. MicroSoft has its own as well.
Ultimately, this is about knowing how to use the debugger for your compiler. Also, realize that using the debugger for your compiler properly can be just as daunting a task as learning how to use your compiler.
There are also profilers available, but again, it will depend somewhat on your compiler as to which ones are available for you. Your keywords for googling will be "C++", "debugger", and "profiler", ideally along with the name of your compiler.
Be aware, as well, that your compiler may impact the statistics when your program runs against the same data.

Emacs, cedet and c++/c++11 support

I usually develop using emacs in a linux environment (ubuntu) because I love the editor. I've been also using eclipse from time to time but I find it slow.
Since I want IDE-like features, I tried to setup cedet and it seems to be sort of doing the work.
I find that cedet never finds base class members. For example, std::vector in gcc has std::vector::size in its base class and it cannot find it.
Seems inaccurate: If I do something like "myvector." it will give me completions like size_type.
Cannot use auto from c++11, it seems not to work.
srecode-getset gives me errors even for basic usage.
My configuration does not give any error and is based in alexott cedet config.
My questions are:
The completion is that inaccurate still? (Think of "vector." giving things like "size_type".
What is the status of cedet for c++/c++11? Should auto be working? I'm doing anything wrong?
I tried to use both bundled ubuntu version and last version from bzr repository. CEDET seems an extremely useful tool, but I wonder if it needs more work.
Thanks in advance.
Instead of relying on CEDET for completion, you might want to consider an alternative completion provider in Emacs.
Auto-complete-clang and auto-complete-clang-async both work with clang to get completions and with the auto-complete package to display them. Company-clang is similar, but uses the company package to display completions.
There is another minor mode for C, C++, and ObjC called irony that uses clang to get completions and can use multiple front-ends to display completions. This might have the best documentation for getting it set up.
All of these are available on Marmalade for use with the package manager in Emacs 24.
I know that this may be a less-than-sufficient answer (and I'd prefer to mention this in the comments but I'm shy on points), but there is an Eclipse plugin for emacs functionality called emacs+. This link should be friendly to your Eclipse install manager (on Indigo I can copy and paste it into Help->Install New Software->Work With). Because Eclipse was otherwise attractive to you and therefore this can indirectly alleviate your problem...
size_type is actually a member type of vector, so that's not as crazy as it sounds. Of course, the syntax is myvector::size_type, not with a period.

As of 2011: Netbeans 7 or Eclipse Indigo for C++?

This is basically a duplicate of:
Netbeans or Eclipse for C++?
But, that question as 3+ years old, and a lot has changed since then.
I have a large code base with a custom (but Makefile based) build system. The areas I am specifically wondering about include:
Syntax highlighting
Code navigation.
Code hints.
"ReSharper style" code helpers.
Documentation integration.
Debugger UI and features.
Has anyone had the chance to evaluate both Netbeans and Eclipse?
EDIT: As a followup question, are any of the Netbeans users here concerned with its future given Oracle's recent bad history with "open" efforts? (Open Solaris, MySQL, Open Office)
Thank you
I cannot comment on eclipse, but on netbeans 7 I will say things that are very important for me and that work fine so far:
code completion, go to declarations
pkg-config automatic include management for parsing
stuff that sometimes works and sometimes don't
find usages, sometimes it might fail to find usages in other open projects
debugger sometimes gets confused with unittest-cpp macros and it will not go on the appropiate line
stuff that are not yet working and i care deeply:
C++0x syntax highlighting (auto, lambdas, enum class, variadic templates, none of them are recognized by the built-in parser)
stuff that is not quite working but i could not care less:
git integration. I enjoy using git from command-line so this is a non-issue
in all, the IDE is very usable. I hope to have a chance to try out latest cdt on Indigo Eclipse, but so far i haven't that much of a real reason to investigate
I cannot comment on Netbeans, but I can offer you information on Eclipse. I work with C++ on UNIX systems, and I have started to use Eclipse when exploring large code bases that I know little about. I don't use it to build, but it would be easy to integrate our build system with it as one only needs commands.
Eclipse has most of what you are looking for: (I'm speaking of Eclipse/CDT)
Not only can you completely customize your syntax highlighting, you can also have it format the code with templates. My company has a code standard for spacing, tabs and formatting of functions and conditional code, and with little effort I was able to modify an existing template to meet our code standards.
The navigation is not bad, if you highlight and hover over a variable, it shows you the definition in a small pop-up bubble. If you do the same for a type, it will you show you where the type is defined. For functions, it will show the first few lines of the implementation of the function, with an option to expand it and see the whole function. I find all of these nice for code discovery and navigation. You can also highlight a variable, and use a right-click menu option to jump to its declaration.
I suppose by code hints you are referring to something like intellisense? This is the main reason why I use Eclipse when looking over a large code base. Just hit the '.' or '->' and a second later you get your options.
The debugger UI is quite capable. You can launch gdb within the tool and it allows you to graphically move through your code just as you would in a tool like ddd or Visual C++. It offers standard features like viewing registers, memory, watching variables, etc.
That being said, I have found some weaknesses. The first is that it doesn't really strongly support revision control systems outside of CVS and SVN very easily (integrated into the GUI). I found a plug-in for the system we use at my company, but it spews XML and Unicode garbage. It was easier to just use the revision control on the command line. I suspect this is the plug-in's issue and not Eclipse. I wish there were better tool integration though.
The second complaint is that for each project I have to manually setup the include directories and library paths. Perhaps with an environment variable this could be circumvented? Or I may just do not know how to set things up correctly. Then again if it is not obvious to a developer how to do this, I consider that a weakness of the tool.
All in all I like working with Eclipse. It is not my main editing environment, but I appreciate it for working on large code bases.
I'm a huge fan of Netbeans. I am in a similar situation to yours, but creating the project was very easy. Just point Netbeans at where the code is checked out and it figures out most things for itself. I rarely have to do any configuration. One thing to note though, if your tree is very large, it can take some time to fully index - and while it does, memory and cpu will be hosed on the box.
The integration with cvs is awesome, and the Hudson integration is very cool for CB. I've not used Git myself, though I should imagine it's a no-brainer.
One thing that does irritate me no end is that it does not behave very well with code relying heavily on templates. i.e. shows lots of warnings and errors about types not being found etc.
I have not used the latest version of Eclipse, I tried the major release before the current one and gave up because it did not have the same smooth project integration with the makefiles etc. I find it's not as nice if you don't want to use it's make system - though I could be wrong.
I don't use any of the code formatting provided, I instead prefer something like AStyle instead. I know that NetBeans does a good job with Java - but have not used it for C++. CDT I seem to remember doing some odd stuff with indentation when formatting C++ code - esp. if templates are involved - but that was atleast two years ago.
Hope some of it helps - the best way to do this is to download and try for yourself and see what works for you. Anything we tell you is purely subjective.
I used to work with Netbeans with MinGW, I Just tried 7.0.1.
I currently use Eclipse Indigo with CDT and MinGW - It's better performance wise (less CPU & Memory).
Netbeans creates a makefile to compile all the time,
In Eclipse you can build directly with the CDT-Toolchain or use Makefile - Eclipse is more flexible.
Debugging: Netbeans might be better in Solaris/Linux.
I Personally rather eclipse over Netbeans, I think eclipse is more professional.
One particular issue that causes me quite a lot of grief with Netbeans 7.0 is that it tends to want to work with utf8 files, and not all of out c++ projects are utf8. It will issue a warning about opening such a file, and if you do open it, will corrupt said file, which is a pain.
I've not found out how to properly make netbeans handle this. Apparently the encoding can be changed, but for the entire project. So presumably changing it to us-acii would stop this problem, although non ascii characters wouldn't display properly.

Edit and Continue on GDB

I know that E&C is a controversial subject and some say that it encourages a wrong approach to debugging, but still - I think we can agree that there are numerous cases when it is clearly useful - experimenting with different values of some constants, redesigning GUI parameters on-the-fly to find a good look... You name it.
My question is: Are we ever going to have E&C on GDB? I understand that it is a platform-specific feature and needs some serious cooperation with the compiler, the debugger and the OS (MSVC has this one easy as the compiler and debugger always come in one package), but... It still should be doable. I've even heard something about Apple having it implemented in their version of GCC [citation needed]. And I'd say it is indeed feasible.
Knowing all the hype about MSVC's E&C (my experience says it's the first thing MSVC users mention when asked "why not switch to Eclipse and gcc/gdb"), I'm seriously surprised that after quite some years GCC/GDB still doesn't have such feature. Are there any good reasons for that? Is someone working on it as we speak?
It is a surprisingly non-trivial amount of work, encompassing many design decisions and feature tradeoffs. Consider: you are debugging. The debugee is suspended. Its image in memory contains the object code of the source, and the binary layout of objects, the heap, the stacks. The debugger is inspecting its memory image. It has loaded debug information about the symbols, types, address mappings, pc (ip) to source correspondences. It displays the call stack, data values.
Now you want to allow a particular set of possible edits to the code and/or data, without stopping the debuggee and restarting. The simplest might be to change one line of code to another. Perhaps you recompile that file or just that function or just that line. Now you have to patch the debuggee image to execute that new line of code the next time you step over it or otherwise run through it. How does that work under the hood? What happens if the code is larger than the line of code it replaced? How does it interact with compiler optimizations? Perhaps you can only do this on a specially compiled for EnC debugging target. Perhaps you will constrain possible sites it is legal to EnC. Consider: what happens if you edit a line of code in a function suspended down in the call stack. When the code returns there does it run the original version of the function or the version with your line changed? If the original version, where does that source come from?
Can you add or remove locals? What does that do to the call stack of suspended frames? Of the current function?
Can you change function signatures? Add fields to / remove fields from objects? What about existing instances? What about pending destructors or finalizers? Etc.
There are many, many functionality details to attend to to make any kind of usuable EnC work. Then there are many cross-tools integration issues necessary to provide the infrastructure to power EnC. In particular, it helps to have some kind of repository of debug information that can make available the before- and after-edit debug information and object code to the debugger. For C++, the incrementally updatable debug information in PDBs helps. Incremental linking may help too.
Looking from the MS ecosystem over into the GCC ecosystem, it is easy to imagine the complexity and integration issues across GDB/GCC/binutils, the myriad of targets, some needed EnC specific target abstractions, and the "nice to have but inessential" nature of EnC, are why it has not appeared yet in GDB/GCC.
Happy hacking!
(p.s. It is instructive and inspiring to look at what the Smalltalk-80 interactive programming environment could do. In St80 there was no concept of "restart" -- the image and its object memory were always live, if you edited any aspect of a class you still had to keep running. In such environments object versioning was not a hypothetical.)
I'm not familiar with MSVC's E&C, but GDB has some of the things you've mentioned:
http://sourceware.org/gdb/current/onlinedocs/gdb/Altering.html#Altering
17. Altering Execution
Once you think you have found an error in your program, you might want to find out for certain whether correcting the apparent error would lead to correct results in the rest of the run. You can find the answer by experiment, using the gdb features for altering execution of the program.
For example, you can store new values into variables or memory locations, give your program a signal, restart it at a different address, or even return prematurely from a function.
Assignment: Assignment to variables
Jumping: Continuing at a different address
Signaling: Giving your program a signal
Returning: Returning from a function
Calling: Calling your program's functions
Patching: Patching your program
Compiling and Injecting Code: Compiling and injecting code in GDB
This is a pretty good reference to the old Apple implementation of "fix and continue". It also references other working implementations.
http://sources.redhat.com/ml/gdb/2003-06/msg00500.html
Here is a snippet:
Fix and continue is a feature implemented by many other debuggers,
which we added to our gdb for this release. Sun Workshop, SGI ProDev
WorkShop, Microsoft's Visual Studio, HP's wdb, and Sun's Hotspot Java
VM all provide this feature in one way or another. I based our
implementation on the HP wdb Fix and Continue feature, which they
added a few years back. Although my final implementation follows the
general outlines of the approach they took, there is almost no shared
code between them. Some of this is because of the architectual
differences (both the processor and the ABI), but even more of it is
due to implementation design differences.
Note that this capability may have been removed in a later version of their toolchain.
UPDATE: Dec-21-2012
There is a GDB Roadmap PDF presentation that includes a slide describing "Fix and Continue" among other bullet points. The presentation is dated July-9-2012 so maybe there is hope to have this added at some point. The presentation was part of the GNU Tools Cauldron 2012.
Also, I get it that adding E&C to GDB or anywhere in Linux land is a tough chore with all the different components.
But I don't see E&C as controversial. I remember using it in VB5 and VB6 and it was probably there before that. Also it's been in Office VBA since way back. And it's been in Visual Studio since VS2005. VS2003 was the only one that didn't have it and I remember devs howling about it. They intended to add it back anyway and they did with VS2005 and it's been there since. It works with C#, VB, and also C and C++. It's been in MS core tools for 20+ years, almost continuous (counting VB when it was standalone), and subtracting VS2003. But you could still say they had it in Office VBA during the VS2003 period ;)
And Jetbrains recently added it too their C# tool Rider. They bragged about it (rightly so imo) in their Rider blog.

Debugging Best Practices for C++ STL/Boost with gdb

Debugging with gdb, any c++ code that uses STL/boost is still a nightmare. Anyone who has used gdb with STL knows this. For example, see sample runs of some debugging sessions in code here.
I am trying to reduce the pain by collecting tips. Can you please comment on the tips I have collected below (particularly which ones you have been using and any changes you would recommend on them) - I have listed the tips is decreasing order of technicality.
Is anyone using "Stanford GDB STL utils" and "UCF GDB utils"? Is there some such utils for boost data structures? The utils above do not seem to be usable recursively, for example for printing vector of a boost::shared_ptr in a legible manner within one command.
Write your .gdbinit file. Include, for example, C++ related beautifiers, listed at the bottom of UCF GDB utils.
Use checked/debug STL/Boost library, such as STLport.
Use logging (for example as described here)
Update: GDB has a new C++ branch.
Maybe not the sort of "tip" you were looking for, but I have to say that my experience after a few years of moving from C++ & STL to C++ & boost & STL is that I now spend a lot less time in GDB than I used to. I put this down to a number of things:
boost smart pointers (particularly "shared pointer", and the pointer containers when performance is needed). I can't remember the last time I had to write an explicit delete (delete is the "goto" of C++ IMHO). There goes a lot of GDB time tracking down invalid and leaking pointers.
boost is full of proven code for things you'd probably hack together an inferior version of otherwise. e.g boost::bimap is great for the common pattern of LRU caching logic. There goes another heap of GDB time.
Adopting unittesting. boost::test's AUTO macros mean it's an absolute doddle to set up test cases (easier than CppUnit). This catches lots of stuff long before it gets built into anything you'd have to attach a debugger to.
Related to that, tools like boost::bind make it easier to design-for-test. e.g algorithms can be more generic and less tied up with the types they operate on; this makes plugging them into test shims/proxies/mock objects etc easier (that and the fact that exposure to boost's template-tasticness will encourage you to "dare to template" things you'd never have considered before, yielding similar testing benefits).
boost::array. "C array" performance, with range checking in debug builds.
boost is full of great code you can't help but learn from
You might look at:
Inspecting standard container (std::map) contents with gdb
I think the easiest and most option is to use logging (well I actually use debug prints, but I think that's not a point). The biggest advantage is that you can inspect any type of data, many times per program execution and then search it with a text editor to look for interesting data. Note that this is very fast. The disadvantage is obvious, you must preselect the data which you want to log and places where to log. However, that is not such a serious issue, because you usually know where in the code bad things are happening (and if not, you just add sanity checks here and there and then, you will know).
Checked/debug libraries are good, but they are better as a testing tool (eg. run it and see if I'm doing anything wrong), and not as good at debugging a specific issue. They can't detect a flaw in user code.
Otherwise, I use plain GDB. It is not that bad as it sounds, although it might be if you are scared by "print x" printing a screenful of junk. But, if you have debugging information, things like printing a member of a std::vector work and if anything fails, you still can inspect the raw memory by the x command. But if I know what I'm looking for, I use option 1 - logging.
Note that the "difficult to inspect" structures are not only STL/Boost, but also from other libraries, like Qt/KDE.