Get Relative Include Path for File with Clang Tooling: A Comprehensive Guide

Are you tired of manually searching for the relative include path for a file in your project? Look no further! In this article, we’ll dive into the world of Clang Tooling and explore how to use it to get the relative include path for a file. Buckle up and get ready to streamline your development workflow!

What is Clang Tooling?

Clang Tooling is a collection of libraries and tools built on top of the Clang compiler frontend. It provides a set of APIs and command-line tools for parsing, analyzing, and manipulating C, C++, and Objective-C code. With Clang Tooling, you can easily write custom tools and plugins to automate tasks, analyze code, and even create your own compiler!

What is the Relative Include Path?

The relative include path is the path to an included file relative to the current file. For example, if you have a file `main.cpp` that includes `header.h` located in a sibling directory, the relative include path would be `../include/header.h`. Getting the relative include path can be a tedious task, especially in large projects with complex directory structures.

Why Do I Need the Relative Include Path?

You might ask, “Why do I need the relative include path?” Well, there are several reasons:

• Dependency analysis: Knowing the relative include path helps you understand the dependencies between files in your project.

• Code completion: Having the relative include path enables you to provide accurate code completion suggestions to your users.

• Code refactoring: When refactoring code, you need to update the include paths to ensure the changes don’t break the build.

• Build systems: Some build systems, like CMake, require the relative include path to generate correct build files.

Getting Started with Clang Tooling

Before we dive into getting the relative include path, let’s set up Clang Tooling.

Installing Clang Tooling

You can install Clang Tooling using your favorite package manager or by building it from source. For this article, we’ll assume you’re using a Linux-based system and have installed Clang Tooling using the following command:

sudo apt-get install clang-7-tool

Writing a Simple Tool

Create a new file called `get_relative_include_path.cpp` and add the following code:

#include "clang/Tooling/CommonOptionsParser.h"
#include "clang/Tooling/Tooling.h"

using namespace clang::tooling;

int main(int argc, const char **argv) {
  CommonOptionsParser op(argc, argv);
  ClangTool Tool(op.getCompilations(), op.getSourcePathList());

  return Tool.run(newFrontendActionFactory(&getRelativeIncludePath));
}

This code sets up a simple Clang Tooling tool that accepts command-line arguments and initializes the Clang compiler frontend.

Getting the Relative Include Path

Now, let’s implement the `getRelativeIncludePath` function to retrieve the relative include path for a file.

class GetRelativeIncludePathAction : public ASTFrontendAction {
public:
  GetRelativeIncludePathAction() {}

  std::unique_ptr<ASTConsumer> 
  newASTConsumer() override {
    return llvm::make_unique<GetRelativeIncludePathConsumer>();
  }
};

class GetRelativeIncludePathConsumer : public ASTConsumer {
public:
  GetRelativeIncludePathConsumer() {}

  void HandleTranslationUnit(ASTContext &Context) override {
    TranslationUnitDecl *TU = Context.getTranslationUnitDecl();
    for (Decl *D : TU->declarations()) {
      if (isa<IncludeDirective>(D)) {
        IncludeDirective *Include = cast<IncludeDirective>(D);
        SourceLocation IncludeLoc = Include->getLocation();
        PresumedLoc PLoc = IncludeLoc.getPresumedLoc();
        if (PLoc.is Valid()) {
          FileManager &FileMgr = Context.getFileManager();
          const FileEntry *File = FileMgr.getFile(PLoc);
          StringRef IncludePath = File->getName();
          StringRef FilePath = PLoc.getFilename();
          llvm::StringRef RelPath = llvm::sys::path::relative(FilePath, IncludePath);
          llvm::outs() << "Relative include path: " << RelPath << "\n";
        }
      }
    }
  }
};

This code defines an `ASTFrontendAction` and an `ASTConsumer` that iterates over the declarations in the translation unit, finds the include directives, and gets the relative include path using the `FileManager` and `sys::path::relative` functions.

Running the Tool

Compile the `get_relative_include_path.cpp` file using the following command:

clang++ -o get_relative_include_path get_relative_include_path.cpp `llvm-config --cxxflags --ldflags --system-libs`

Now, run the tool on a sample file, for example, `main.cpp`:

./get_relative_include_path main.cpp

The tool will output the relative include path for each included file in `main.cpp`.

Troubleshooting and Optimization

If you encounter any issues or want to optimize the tool, here are some tips:

• Check the Clang version: Ensure you’re using a compatible Clang version, as some features may be deprecated or changed in newer versions.

• Verify file permissions: Make sure the tool has the necessary permissions to access the files and directories.

• Optimize the tool: You can optimize the tool by using parallel processing, caching, or other techniques to reduce the execution time.

• Use the correct include paths: Ensure the tool is using the correct include paths and system headers.

Conclusion

In this article, we explored how to use Clang Tooling to get the relative include path for a file. By following the instructions, you should now have a working tool that simplifies this task. Remember to optimize and troubleshoot your tool as needed, and happy coding!

Clang Tooling Version	Supported Platforms	Required Dependencies
Clang 7	Linux, macOS, Windows	LLVM, libclang

For more information on Clang Tooling, visit the official documentation: https://clang.llvm.org/docs/Tooling.html

Frequently Asked Questions

Exploring the world of Clang tooling and seeking answers about getting relative include paths for files? You’re in the right place! Below, we’ve got the most frequently asked questions and their solutions to get you started.