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A free tool to check C/C++ source code against a set of coding standards?
I am starting a c++ project involving several people I have no direct access to. We agreed on a coding style guide, which e.g. defines the casing for class members depending on the accessibility (i.e. privates in pascal case, publics and protecteds in camel case. Please, don't start discussions about the style guide. I had enough. Thank you.).
What I want to do now is to generate some reporting of style guide violations. I don't want to enforce the style guide, e.g. at commit, but I want to provide a tool which each developer can use to see where his/her code violates the style guide (if he/she wants to check it).
Do you know a tool which can do the Job?
(It needs to be able to understand some C++, e.g. to detect the accessibility of class members.)
well, you could run your code through AStyle or Uncrustify on commit, which would at least re-format bad code to some standard. I find that's the majority problem with code commits and standards - if you reformat after commmit, it shows up as a lot of delta changes that are entirely trivial.
Otherwise, check the other SO answer.
Style guides tends to be company-specific, and one has to write company-specific checks to achieve them.
My company offers customizable C++ style checkers, in which one can check for deprecated idioms by syntax, check that variables and types have certain properties, or verify that certain commands occur in certain orders locally. These checkers use C++ dialect precise parsers on the source code. The customization isn't easy; you need the underlying engine and some knowledge of parsing C++ programs.
It is possible to write rules that check for layout, but it is a lot of unrewarding work, and resolving such complaints isn't a productive use of programmer resource IMHO. And if you aren't going to enforce your style, why are you annoying the programmer with complaints at all? IT seems easier (as another poster noted) to simply run a layout-formatter that produces the right result at no cost to the programmer.
One of the issues with generic formatters is that being language-imprecise, they may misinterpret the source code and sometimes break it as they format, leading to compilation errors, debugging and wasted time. We also offer C++ Formatters to accomplish the formatting using the same language precise parsers as the style checker; they can't break your code during reformatting.
I've been successfully using the vera++ tool to do this for our projects. I've wrote a number of rules (in TCL) to adopt our company style guidelines. It was a bit painful, until I came around all the false positives reported from my checks. At least it's working well now and I have integrated the reports to the Jenkins build analysis.
The reports can also be easily adopted to a custom error analysis in the Eclipse IDE.
Related
What I want to do is to have a tool run by my CI server to scan the code and detect any coding standard violations present based on a defined guideline. I will use the output to prompt build "fails" until the issue is fixed.
The problem I have is that my engineers are spending most of their time in code reviews looking for coding standards violations and not looking for bugs (70-76% of defects found are standards related). My theory is if they don't need to look for violations of standards they will branch out as to what they are looking for.
Does anything like this exist?
What you want is called static analysis
2 of them are free :
cppcheck — Open-source tool that checks for several types of errors,
including use of STL.
cpplint Open source, automated checker to make
sure a C++ file follows Google's C++ style.
Then some comercial compilers include static analysis : Visual Studio (Team system and above)
Intel compiler (I've heard it's very customizable, but I haven't personally used it yet)
If issues related to code formatting - you can enforce invocation of code beautifiers on checkin to repository (astyle, indent, ...)
Next one is PC-lint/Flexelint tool, which also has rules to enforce various coding standard guidelines. But it is non-free. You have to familiarize with it and configure it properly to avoid false positives.
You also can check Vera++, but I've no experience with it.
We are going to start a new project in our team which consists of less than 10 developers.
We have access to modern IDEs such as VS2010.
The project is extremely dynamic (users' needs change very quick) and cross platform. Therefore, I need a highly readable and very detailed C++ coding standard so new developers can easily change the old codes in future. I also need a not to write list so the code will compile on different OSes (at least windows and linux).
Is there such a standard?
Are coding standards expired already?
Coding standards remain an issue because everyone secretly thinks they can solve all the world's programming problems with a very clever coding standard. And then forcing programmers to follow them. (Pretty much like programming programmers.)
Unfortunately, few coding standards address the issues that matter in a complex project like:
how to cleanly and effectively partition and model a problem
how program partitions should best interact with others
how an explanation of logic ("comment") should be written to explain the code
Instead, most coding standards address trivia like:
indentation and brace style
whether comments should be present or not
mechanical rules about constructing identifiers
placing arbitrary limits on characters in a line, number of parameters, etc., etc.
As for the primary question, I don't know of any good detailed standards other than design and implement code which other engineers would be proud of.
Read C++ Coding Standards. It is not what most people would call a coding standards document, but you probably want to read it. One of the first guides is do not swell the small stuff (do not put too much emphasis on details: focus on rules that affect the semantic not the syntax, as in prefer RAII over raw pointers instead of add braces everywhere, in it's own line and indenting 3 spaces)
As far as coding standard go, in most cases, it's less important what the specific coding standards are, so long as they're firmly in place. Tabs vs. space? Who cares. Pick one and go with it. Curly braces on the same line as the conditional or the next line? Who cares. Pick one and stay consistent.
I personally like the Linux kernel coding standards.
http://www.kernel.org/doc/Documentation/CodingStyle
It is for C, and not C++, but it may be a good place to start on the standards for your project. Unfortunately, I doubt it offers suggestions on a "do not write" list.
I highly recommend the Google style guide, which I haven't stopped using since interning there two years ago. The link above enumerates the rules in detail, along with each rule's justification in terms of pros and cons.
It is indeed highly readable and very detailed, but the important rules (the ones that come up all the time) are few and easy to remember. They have really streamlined my C++ coding by giving consistency to my naming and function argument-passing conventions.
I know you're using an IDE, but emacs users can use their "google.el" file for automatic formatting. There's also a powerful "cpplint" script that runs through a source file, printing out style violations in the same warning format as used by gcc. This lets you quickly fix style violations before checking in a file. If your IDE can parse gcc warnings and jump from warning to warning in a source file, then fixing such violations becomes a snap. Emacs and Eclipse CDT do this, as do other editors/IDEs.
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What are some good tools for getting a quick start for parsing and analyzing C/C++ code?
In particular, I'm looking for open source tools that handle the C/C++ preprocessor and language. Preferably, these tools would use lex/yacc (or flex/bison) for the grammar, and not be too complicated. They should handle the latest ANSI C/C++ definitions.
Here's what I've found so far, but haven't looked at them in detail (thoughts?):
CScope - Old-school C analyzer. Doesn't seem to do a full parse, though. Described as a glorified 'grep' for finding C functions.
GCC - Everybody's favorite open source compiler. Very complicated, but seems to do it all. There's a related project for creating GCC extensions called GEM, but hasn't been updated since GCC 4.1 (2006).
PUMA - The PUre MAnipulator. (from the page: "The intention of this project is to
provide a library of classes for the analysis and manipulation of C/C++ sources. For this
purpose PUMA provides classes for scanning, parsing and of course manipulating C/C++
sources."). This looks promising, but hasn't been updated since 2001. Apparently PUMA has been incorporated into AspectC++, but even this project hasn't been updated since 2006.
Various C/C++ raw grammars. You can get c-c++-grammars-1.2.tar.gz, but this has been unmaintained since 1997. A little Google searching pulls up other basic lex/yacc grammars that could serve as a starting place.
Any others?
I'm hoping to use this as a starting point for translating C/C++ source into a new toy language.
Thanks!
-Matt
(Added 2/9): Just a clarification: I want to extract semantic information from the preprocessor in addition to the C/C++ code itself. I don't want "#define foo 42" to disappear into the integer "42", but remain attached to the name "foo". This, unfortunately, excludes several solutions that run the preprocessor first and only deliver the C/C++ parse tree)
Parsing C++ is extremely hard because the grammar is undecidable. To quote Yossi Kreinin:
Outstandingly complicated grammar
"Outstandingly" should be interpreted literally, because all popular languages have context-free (or "nearly" context-free) grammars, while C++ has undecidable grammar. If you like compilers and parsers, you probably know what this means. If you're not into this kind of thing, there's a simple example showing the problem with parsing C++: is AA BB(CC); an object definition or a function declaration? It turns out that the answer depends heavily on the code before the statement - the "context". This shows (on an intuitive level) that the C++ grammar is quite context-sensitive.
You can look at clang that uses llvm for parsing.
Support C++ fully now link
The ANTLR parser generator has a grammar for C/C++ as well as the preprocessor. I've never used it so I can't say how complete its parsing of C++ is going to be. ANTLR itself has been a useful tool for me on a couple of occasions for parsing much simpler languages.
Depending on your problem GCCXML might be your answer.
Basically it parses the source using GCC and then gives you easily digestible XML of parse tree.
With GCCXML you are done once and for all.
pycparser is a complete parser for C (C99) written in Python. It has a fully configurable AST backend, so it's being used as a basis for any kind of language processing you might need.
Doesn't support C++, though. Granted, it's much harder than C.
Update (2012): at this time the answer, without any doubt, would be Clang - it's modular, supports the full C++ (with many C++-11 features) and has a relatively friendly code base. It also has a C API for bindings to high-level languages (i.e. for Python).
Have a look at how doxygen works, full source code is available and it's flex-based.
A misleading candidate is GOLD which is a free Windows-based parser toolkit explicitly for creating translators. Their list of supported languages refers to the languages in which one can implement parsers, not the list of supported parse grammars.
They only have grammars for C and C#, no C++.
Parsing C++ is a very complex challenge.
There's the Boost/Spirit framework, and a couple of years ago they did play with the idea of implementing a C++ parser, but it's far from complete.
Fully and properly parsing ISO C++ is far from trivial, and there were in fact many related efforts. But it is an inherently complex job that isn't easily accomplished, without rewriting a full compiler frontend understanding all of C++ and the preprocessor. A pre-processor implementation called "wave" is available from the Spirit folks.
That said, you might want to have a look at pork/oink (elsa-based), which is a C++ parser toolkit specifically meant to be used for source code transformation purposes, it is being used by the Mozilla project to do large-scale static source code analysis and automated code rewriting, the most interesting part is that it not only supports most of C++, but also the preprocessor itself!
On the other hand there's indeed one single proprietary solution available: the EDG frontend, which can be used for pretty much all C++ related efforts.
Personally, I would check out the elsa-based pork/oink suite which is used at Mozilla, apart from that, the FSF has now approved work on gcc plugins using the runtime library license, thus I'd assume that things are going to change rapidly, once people can easily leverage the gcc-based C++ parser for such purposes using binary plugins.
So, in a nutshell: if you the bucks: EDG, if you need something free/open source now: else/oink are fairly promising, if you have some time, you might want to use gcc for your project.
Another option just for C code is cscout.
The grammar for C++ is sort of notoriously hairy. There's a good thread at Lambda about it, but the gist is that C++ grammar can require arbitrarily much lookahead.
For the kind of thing I imagine you might be doing, I'd think about hacking either Gnu CC, or Splint. Gnu CC in particular does separate out the language generation part pretty thoroughly, so you might be best off building a new g++ backend.
Actually, PUMA and AspectC++ are still both actively maintained and updated. I was looking into using AspectC++ and was wondering about the lack of updates myself. I e-mailed the author who said that both AspectC++ and PUMA are still being developed. You can get to source code through SVN https://svn.aspectc.org/repos/ or you can get regular binary builds at http://akut.aspectc.org. As with a lot of excellent c++ projects these days, the author doesn't have time to keep up with web page maintenance. Makes sense if you've got a full time job and a life.
how about something easier to comprehend like tiny-C or Small C
Elsa beats everything else I know hands down for C++ parsing, even though it is not 100% compliant. I'm a fan. There's a module that prints out C++, so that may be a good starting point for your toy project.
See our C++ Front End
for a full-featured C++ parser: builds ASTs, symbol tables, does name
and type resolution. You can even parse and retain the preprocessor
directives. The C++ front end is built on top of our DMS Software Reengineering
Toolkit, which allows you to use that information to carry out arbitrary
source code changes using source-to-source transformations.
DMS is the ideal engine for implementing such a translator.
Having said that, I don't see much point in your imagined task; I don't
see much value in trying to replace C++, and you'll find building
a complete translator an enormous amount of work, especially if your
target is a "toy" language. And there is likely little point in
parsing C++ using a robust parser, if its only purpose is to produce
an isomorphic version of C++ that is easier to parse (wait, we postulated
a robust C++ already!).
EDIT May 2012: DMS's C++ front end now handles GCC3/GCC4/C++11,Microsoft VisualC 2005/2010. Robustly.
EDIT Feb 2015: Now handles C++14 in GCC and MS dialects.
EDIT August 2015: Now parses and captures both the code and the preprocessor directives in a unified tree.
EDIT May 2020: Has been doing C++17 for the past few years. C++20 in process.
A while back I attempted to write a tool that will automatically generate unit tests for c files.
For preprosessing I put the files thru GCC. The output is ugly but you can easily trace where in the original code from the preprocessed file. But for your needs you might need somthing else.
I used Metre as the base for a C parser. It is open source and uses lex and yacc. This made it easy to get up and running in a short time without fully understanding lex & yacc.
I also wrote a C app since the lex & yacc solution could not help me trace functionality across functions and parse the structure of the entire function in one pass. It became unmaintainable in a short time and was abandoned.
What about using a tool like GNU's CFlow, that can analyse the code and produce charts of call-graphs, here's what the opengroup(man page) has to say about cflow. The GNU version of cflow comes with source, and open source also ...
Hope this helps,
Best regards,
Tom.
When programming in C++ in Visual Studio 2008, why is there no functionality like that seen in the refactor menu when using C#?
I use Rename constantly and you really miss it when it's not there. I'm sure you can get plugins that offer this, but why isn't it integrated in to the IDE when using C++? Is this due to some gotcha in the way that C++ must be parsed?
The syntax and semantics of C++ make it incredibly difficult to correctly implement refactoring functionality. It's possible to implement something relatively simple to cover 90% of the cases, but in the remaining 10% of cases that simple solution will horribly break your code by changing things you never wanted to change.
Read http://yosefk.com/c++fqa/defective.html#defect-8 for a brief discussion of the difficulties that any refactoring code in C++ has to deal with.
Microsoft has evidently decided to punt on this particular feature for C++, leaving it up to third-party developers to do what they can.
I'm not sure why it is like this, but third-party tools exist that help. For example, right now I'm evaluating Visual Assist X (by Whole Tomato). We're also using Visual Studio 2005.
devexpress provides Add-in Refactor! for C++ for VS2005 and VS2008.
Don't feel hard-done-by, it isn't available in VB.Net either :)
C++ is a HARD language to parse compared with C# (VB too unless you've "Option Explicit" and "Option Strict" switched on, it's difficult to tell exactly what any line of code is doing out of a MUCH larger context).
At a guess it could have something to do with the "difficulty" of providing it.
P.S. I marked my answer as community wiki because I know it's not providing any useful information.
Eclipse does few c++ refactorings including 'rename'. Check out this question here on StackOverflow.
It is also possible to use Microsoft compiler with Eclipse. Check out here.
Try Eclipse and see if it fits for you.
There is a lot of fud and confusion around this issue. This amazing youtube video should clear up why C++ refactoring is hard: https://www.youtube.com/watch?v=mVbDzTM21BQ
tl;dr Google refactors their entire 100 million line C++ codebase by using a compiler (Clang + LLVM) that allows access to its intermediate format.
Bottom line, third parties are screwed here, there is no realistic way for them to refactor VS C++ unless MS outputs intermediate results the same way. If you think of it from the programming problem perspective this is obvious: in order to refactor VS C++ you have to be able to compile C++ the exact same way VS does with the same bugs, limitations, flaws, hacks, shortcuts, workarounds, etc. The usual suspects like Coderush and Resharper do not have the budget for that kind of insanity although apparently they are trying but it has been years...
http://www.jetbrains.com/resharper-cpp/
Update 2016: Resharper now does a decent job at C++ refactor. Limitations are purely for large / gigantic projects.
MS has finally done this: https://channel9.msdn.com/Shows/C9-GoingNative/GoingNative-33-C-Refactoring-in-Visual-Studio-2015#time=04m37s
They have started doing this about 10 years ago, I remember watching ms channel9 long ago.
I've been using Visual Assist X with visual studio for about one year and a half. It's an incredible tool that helps you a lot with ordinary C++ code, but it doesn't perform very well on templated code. For instance, you if have a sophisticated policy-based template design, it won't know how to rename your variables, and the project won't compile anymore.
Install plugin which enables you that functionality: https://visualstudiogallery.msdn.microsoft.com/164904b2-3b47-417f-9b6b-fdd35757d194
I'd like to point out that Qt Creator (a C++ IDE which is compatible with VC++ libraries and build system) provides symbol renaming that works very well:
You can rename symbols in all files in a project. When you rename a class, you can also change filenames that match the class name.
Qt Creator - Refactoring: Renaming Symbols
Qt Creator's rename functionality gives you a list of the symbol references it found and an opportunity to exclude any of them before performing the replace. So if it gets a symbol reference wrong, you can exclude it.
So C++ symbol renaming is possible. Coming to VS from Qt Creator I feel your pain, to the point where I've considered converting preexisting VS projects of considerable size to use Qt Creator instead.
I don't buy the argument that this is specifically hard in C++. In addition to the fact that it already works very well in Qt Creator, there's the fact that the compiler and linker can find and match symbols: If that wasn't possible you couldn't build your application.
In fact, languages like Python that are dynamically typed also have renaming tools. If you can create such a tool for a language where there are no explicit references to variable type you can definitely do it for C++.
Case in point:
... Rope, a python refactoring library... I tried it for a few renames, and that definitely worked as expected.
Stack Overflow - What refactoring tools do you use for Python?
Well in spite of comments by all you experts I totally disagree that refactoring support issue has something to do with C++ language semantics or any language semantics for that matter. Except the compiler builder themselves don't choose to implement one in first case due to their own reasons or constraints whatsoever they maybe.
And offense not to be taken but I am sorry to say Mr jsb the above link you provided to support your case (i.e of yosefk) about C++ defect is totally out of question. Its more like you providing direction to "Los angeles" when someone asked for of "San Franisco".
In my opinion raising refactoring difficulty issue for certain language is more like raising a finger on language integrity itself. Especially for languages which is sometimes just pain.... when it comes to their variable declaration and use. :) Okay! tell me how come you loose track of some node within a node tree ... eh? So what it is do with any language be it as simple as machine level code. You know you VS compiler can easily detect if some variable or routine is dead code. Got my point?
About developing third party tool. I think compiler vendors can implement it far more easily and effectively if they ever wanted to then a third party tool which will have to duplicate all the parsing database to handle it. Nowadays compiler can optimize code very efficiently at machine code level and I am hearing here that its difficult to tell how some variable is used previously. You haven't paid any real attention to inner working of compiler I suppose. What database it keep within.
And sure its the almost same database that IDE use for all such similar purposes. In previous time compiler were just a separate entity and IDE just a Text Editor with some specialization but as times goes by the gap between compiler and IDE Editor become less and its directly started working on similar parsed database. Which makes it possible to handle all those intellisense and refactoring or other syntax related issues more effectively. With all precompile things and JIT compiling this gap is almost negligent. So it almost make sense to use same database for both purpose or else your memory demand go higher due to duplication.
You all are programmers - I am not! And you guys seems to be having difficulty visualizing how refactoring can be implemented for C++ or any language that I can't comprehend. Its just all about for something you have to put more effort for some less depending on how heavy is a person you trying push.
Anyway way VS a nice IDE especially when it comes to C#.
I'm currently in the process of learning C++, and because I'm still learning, I keep making mistakes.
With a language as permissive as C++, it often takes a long time to figure out exactly what's wrong -- because the compiler lets me get away with a lot. I realize that this flexibility is one of C++'s major strengths, but it makes it difficult to learn the basic language.
Is there some tool I can use to analyze my code and make suggestions based on best practices or just sensible coding? Preferably as an Eclipse plugin or linux application.
Enable maximum compiler warnings (that's the -Wall option if you're using the Gnu compiler).
'Lint' is the archetypical static analysis tool.
valgrind is a good run-time analyzer.
I think you'd better have some lectures about good practices and why they are good. That should help you more than a code analysis tool (in the beginning at least).
I suggest you read the series of Effective C++ and **Effective STL books, at least. See alsot The Definitive C++ Book Guide and List
For g++, as well as turning on -Wall, turn on -pedantic too, and prepare to be suprised at the number of issues it finds!
Tool support for C++ is quite bad compared to Java, C#, etc. because it does not have a context-free grammar. In fact, there are parts of the C++ grammar that are undecidable. Basically, that means that understanding C++ code at the syntactic level requires implementing pretty much a compiler front end with semantic analysis. C++ cannot be parsed into an AST independently of semantic analysis, and most code analysis tools in IDEs, etc. work at the AST level. This is part of the tradeoff you make in exchange for the flexibility and backwards compatibility of C++.
Turning on all compiler warnings (at least initially) and then understanding what they mean, how to fix the problems highlighted and which of the warnings represent genuine constructs that compiler writers might consider ambiguous is a good first step.
If you need something more heavy duty, you could try PC-Lint if you're on Windows, which is still one of the best lint tools for C++. Just keep in mind that you'll need to configure these tools to reflect your coding style, otherwise you'll get swamped with warnings and won't be able to see the wood for the trees. Yes, it costs money and it's probably a bit overkill if you're not doing C++ on a "getting paid for it" level, but I find it invaluable.
There is as list of static code analysis tools at wikipedia.
But warnings are generally good but one problem with enabling all warnings with pedantic and Wall is the number of warnings you might get from including headers that you have no control over, this can create a lot of noise. I prefer to compile my own software with all warnings enabled though. As I program in linux I usually do like this:
Put the external headers I need to include in a separate file, and in the beginning of that file before the includes put:
#pragma GCC system_header
And then include this file from your code. This enables you to see all warnings from your own code without it being drowned in warnings from external code. The downside is that it's a gcc specific solution, I am not aware of any platform independent solution to this.
lint - there are lots of versions but if you google for lint you should find one that works. The other thing to do is turn on your compiler warnings - if you are using gcc/g++ the option is -Wall.
You might find CppChecker helpful as a plugin for Eclipse that supports gcc/PC lint.
I think that really what you need to learn here is how to debug outside of an IDE. This is a valuable skill in my opinion, since you will no longer require such a heavy toolset to develop software, and it will apply to the vast majority of languages you already know and will ever learn.
However, its a difficult one to get used to. You will have to write code just for debugging purposes, e.g. write checks after each line not yet debugged, to ensure that the result is as expected, or print the values to the console or in message boxes so that you can check them yourself. Its tedious but will enable you to pick up on your mistakes more easily, inside or outside of an IDE.
Download and try some of the free debugging tools like GDB too, they can help you to probe memory, etc, without having to write your own code.