Clang libtooling tutorial

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I get "fatal error: 'iostream' file not found". Now, if I try to compile a test file using:.

Then I get "fatal error: 'unistd. Clang comes with some custom includes. The CommonOptionsParser allows you to read commands from the command line that are passed to the compiler.

For example, you can now call your tool like this:. Everything after the double dash will be passed to the compiler. You can specify you own paths instead after -I. The compiler should have been configured to know where to look for its standard libraries without having to specify the environment variable paths. Learn more. Asked 5 years, 4 months ago. Active 4 years, 5 months ago. Viewed 3k times. I am running OS X Yosemite Jonathan Sharman Jonathan Sharman 5 5 silver badges 14 14 bronze badges.

Active Oldest Votes. You can leave out this line. For example, you can now call your tool like this: your-tool yoursourcefile. Hope it helped someone : Ask me if I wasn't specific enough.

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Alex H. Ethan Ethan 5 5 silver badges 6 6 bronze badges. Use homebrew and install llvm using the command brew install llvm Your problem should be solved. V Shreyas V Shreyas 3 3 silver badges 18 18 bronze badges. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Featured on Meta. Community and Moderator guidelines for escalating issues via new response….GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

LibTooling is a library to support writing standalone tools based on Clang. This document will provide a basic walkthrough of how to write a tool using LibTooling. In this tutorial, we'll demonstrate the different ways of running Clang's SyntaxOnlyActionwhich runs a quick syntax check, over a bunch of code.

Let me give you an example:. Once you unit tested your FrontendAction to the point where it cannot possibly break, it's time to create a standalone tool.

For a standalone tool to run clang, it first needs to figure out what command line arguments to use for a specified file. To that end we create a CompilationDatabase. There are different ways to create a compilation database, and we need to support all of them depending on command-line options. There's the CommonOptionsParser class that takes the responsibility to parse command-line parameters related to compilation databases and inputs, so that all tools share the implementation.

CompilationDatabase can be read from a build directory or the command line. Using CommonOptionsParser allows for explicit specification of a compile command line, specification of build path using the -p command-line option, and automatic location of the compilation database using source files paths.

For example, to run the SyntaxOnlyAction over the files "a. Now we combine the two previous steps into our first real tool. You can run clang-check on a file in the llvm repository by specifying all the needed parameters after a " -- " separator:. As an alternative, you can also configure cmake to output a compile command database into its build directory:.

Clang tools need their builtin headers and search for them the same way Clang does.

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This works out-of-the-box for tools running from llvm's toplevel binary directory after building clang-resource-headers, or if the tool is running from the binary directory of a clang install next to the clang binary. Tips: if your tool fails to find stddef. Skip to content. Code Pull requests 0 Actions Security Pulse. Permalink Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

Sign up. Branch: master. Find file Copy path. Cannot retrieve contributors at this time. Raw Blame History. LibTooling LibTooling is a library to support writing standalone tools based on Clang.

Parsing a code snippet in memory If you ever wanted to run a FrontendAction over some sample code, for example to unit test parts of the Clang AST, runToolOnCode is what you looked for. In case of error it will terminate the program. ClangTool Tool OptionsParser. Thus, it takes a FrontendActionFactory as parameter.

You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window.In order to work on the compiler, you need some basic knowledge of the abstract syntax tree AST. For further information, see the getting started guide. Next you need to obtain the CMake build system and Ninja build tool.

All of the tests should pass, though there is a very small chance that you can catch LLVM and Clang out of sync. Running 'git svn rebase' in both the llvm and clang directories should fix any problems.

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The second command will bring up a GUI for configuring Clang. Press 't' to turn on advanced mode. With that done, Ninja will be able to compile our tool. A detailed explanation of why the different parts are needed can be found in the LibTooling documentation. You can compile our new tool by running ninja from the build directory. Try it! Note the two dashes after we specify the source file.

Clang recently introduced the ASTMatcher library to provide a simple, powerful, and concise way to describe specific patterns in the AST. For example, suppose you wanted to examine only binary operators. There is a matcher to do exactly that, conveniently named binaryOperator. Shockingly, it will match against addition expressions whose left hand side is exactly the literal 0. All matcher that are nouns describe entities in the AST and can be bound, so that they can be referred to whenever a match is found.

To do so, simply call the method bind on these matchers, e. Okay, on to using matchers for real. Next, we want to specify that a single variable is declared in the first portion of the loop, so we can extend the matcher to. The last step is giving the matcher a name and binding the ForStmt as we will want to do something with it:.

Once you have defined your matchers, you will need to add a little more scaffolding in order to run them. More code! Now, you should be able to recompile and run the code to discover for loops. Create a new file with a few examples, and test out our new handiwork:. Our simple matcher is capable of discovering for loops, but we would still need to filter out many more ourselves.

We can do a good portion of the remaining work with some cleverly chosen matchers, but first we need to decide exactly which properties we want to allow.That post was and still is quite popular, but also severely out of date; it's time to fix that. Clang is moving forward very fast.

Today, to develop tools similar to the one presented in that post one should use the "tooling" library libTooling. I hinted at its existence even in that post, but it was still at its infancy then. Now libTooling is a fairly mature layer through which it's possible to interact with Clang. So I rewrote the tool presented in the previous post using libTooling. The tool is very basic, but it demonstrates a lot of the machinery. If you've ever tried to build an out-of-tree tool using LLVM or Clang as a library, you will not underestimate the utility of having this makefile available and continuously updated.

The low-level details of the sample haven't changed much. Finally, a Rewriter is used to manage the textual changes to the source code. This is how Clang-based source to source transformations work - analysis of the AST lets us find out where to apply changes, and a Rewriter is used to actually apply those changes [2].

The link between the two is the very accurate source location information managed by the AST for each node. What's really new about this sample is how it turns this low-level transformation logic into an actual tool. With libTooling, we no longer need to laboriously set up an instance of the compiler front-end manually.

The ClangTool class does it all for us, while CommonOptionsParser simplifies the command-line interface of the tool. All we need is to implement a FrontendAction - a very central abstraction within Clang for entities that produce stuff from the parsed AST [3]. MyFrontendAction is very simple. Note that ClangTool will create a new MyFrontendAction instance per file, so it's correct to have a new Rewriter in each instance.

This is enabled by adding another layer of abstraction - the FrontendActionFactory. The factory pattern here is used to decouple the process of creating objects implementing FrontendAction from the concrete FrontendAction subclasses used by our tool. It also lets us customize the creation process to a greater extent - for example passing additional information into each MyFrontendAction object.

In our sample, advanced features aren't really needed so we use the convenience newFrontendActionFactory template which creates a basic factory behind the scenes. It's important to spend a few minutes to discuss how to invoke the tool. Describing compilation databases in detail is out of scope here, and I may devote a separate post to it in the future, but in the meantime it helps knowing that a compilation database isn't strictly required to run tools.

The libTooling command-line parser CommonOptionsParser supports providing compiler flags on the command line, following the special flag Think of it as a simplified, ad-hoc version of a compilation database.

If you clone and build the llvm-clang-samples repository, you can invoke the sample discussed here as follows:. Note the -- at the end: this invocation means there are no special flags the tool needs to know about while analyzing the file.

YVR18-223:How to build a C++ processing tool using the Clang libraries.

This post provides an introduction into building a source-to-source transformation tool based on Clang's libTooling. It should provide a foundation for building custom tools, and nicely complements the existing Clang libTooling documentation and examples. Check them out, by the way. Clang actually has decent documentation on using libTooling these days. For comments, please send me an emailor reach out on Twitter. Toggle navigation Eli Bendersky's website.LibTooling is a library to support writing standalone tools based on Clang.

This document will provide a basic walkthrough of how to write a tool using LibTooling. Let me give you an example:. For a standalone tool to run clang, it first needs to figure out what command line arguments to use for a specified file.

To that end we create a CompilationDatabase. There are different ways to create a compilation database, and we need to support all of them depending on command-line options. CompilationDatabase can be read from a build directory or the command line. Using CommonOptionsParser allows for explicit specification of a compile command line, specification of build path using the -p command-line option, and automatic location of the compilation database using source files paths.

Now we combine the two previous steps into our first real tool. As an alternative, you can also configure cmake to output a compile command database into its build directory:. Now you can run clang-check over files in the project by specifying the build path as first argument and some source files as further positional arguments:.

Clang tools need their builtin headers and search for them the same way Clang does. Tips: if your tool fails to find stddef. Clang 11 documentation LibTooling. In case of error it will terminate the program. ClangTool Tool OptionsParser. Thus, it takes a FrontendActionFactory as parameter.

Created using Sphinx 1.You can also use this code in the Plugin environment with just a few simple changes. Onwards to the example! Note: this is a continuation of Clang Tutorial: Part I. First, we need to set up some structure. Clang comes packaged with a good Plugin example, but not a LibTooling example.

Here is the full source code for this LibTooling example. Everything in main is fairly self-explanatory, except rewriterwhich is explained later. You cannot do this with a Clang Plugin.

We also need a few global variables at the top of the file :. Nothing too complex going on here. You can override however many functions you wish, so that your code will be called when a certain type of AST item has been parsed.

Basically, this code uses our ExampleVisitor described below to visit the AST nodes in each top-level declaration in the entire source file. For test.

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However, overriding HandleTopLevelDecl means that your code in that function will be immediately called each time a new Decl is parsed in the source, not after the entire source file has been parsed.

In this case, a translation unit effectively represents an entire source file.

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The previous two sections were just to set up infrastructure. This same format works with any AST class. Based on our objective of rewriting function definitions and statements, we only need to override VisitFunctionDecl and VisitStmt.

The above code introduces the Rewriter class, which lets you make textual changes to the source code. It is commonly used for refactoring or making small code changes. The script below has examples of all three:. Assuming you were able to run your analysis script, congratulations on your first foray into Clang!

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You should see the following output:. More specifically, the path under llvm-src should at least contain the source code and the path under llvm-build should contain the Makefile. Hm, that's unusual. I thought perhaps my Makefile was wrong, but I just tried following my own instructions from scratch on a clean install of Ubuntu, and everything worked well. Have you been able to build any other Clang examples? I assume you installed and compiled LLVM and Clang correctly, and that you're running "make" inside of the example directory.

Aside from that, I honestly don't know what the problem is… any other information you can give me? Thanks for tutorial! How can I check if obj-c method was overridden in my class, is there any simple way? I use the following Makefile instead, it would work but compiling is very slow, I guess it's due to static link too many libraries…?

Glad you got it to work! I'm not exactly sure why my Makefile wouldn't work for you, sorry. Note that my example uses Clang's existing build system within the Clang development directories.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again.

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It is inspired by this blogand I have modified some codes to be suitable for the newest Clang 3. What changes most? So, I make some changes in pointer types.

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Finally, makefile has been modified for general purpose use. Skip to content. Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Sign up. Basic Clang library, LibTooling and Plugin. Branch: master. Find file. Sign in Sign up. Go back. Launching Xcode If nothing happens, download Xcode and try again.

Latest commit Fetching latest commit…. Usage See details in readme. You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window.