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Choosing the Right Interface for Your Application
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Clang provides infrastructure to write tools that need syntactic and semantic
information about a program. This document will give a short introduction of
the different ways to write clang tools, and their pros and cons.
LibClang
--------
`LibClang <https://clang.llvm.org/doxygen/group__CINDEX.html>`_ is a stable high
level C interface to clang. When in doubt LibClang is probably the interface
you want to use. Consider the other interfaces only when you have a good
reason not to use LibClang.
Canonical examples of when to use LibClang:
* Xcode
* Clang Python Bindings
Use LibClang when you...:
* want to interface with clang from other languages than C++
* need a stable interface that takes care to be backwards compatible
* want powerful high-level abstractions, like iterating through an AST with a
cursor, and don't want to learn all the nitty gritty details of Clang's AST.
Do not use LibClang when you...:
* want full control over the Clang AST
Clang Plugins
-------------
:doc:`Clang Plugins <ClangPlugins>` allow you to run additional actions on the
AST as part of a compilation. Plugins are dynamic libraries that are loaded at
runtime by the compiler, and they're easy to integrate into your build
environment.
Canonical examples of when to use Clang Plugins:
* special lint-style warnings or errors for your project
* creating additional build artifacts from a single compile step
Use Clang Plugins when you...:
* need your tool to rerun if any of the dependencies change
* want your tool to make or break a build
* need full control over the Clang AST
Do not use Clang Plugins when you...:
* want to run tools outside of your build environment
* want full control on how Clang is set up, including mapping of in-memory
virtual files
* need to run over a specific subset of files in your project which is not
necessarily related to any changes which would trigger rebuilds
LibTooling
----------
:doc:`LibTooling <LibTooling>` is a C++ interface aimed at writing standalone
tools, as well as integrating into services that run clang tools. Canonical
examples of when to use LibTooling:
* a simple syntax checker
* refactoring tools
Use LibTooling when you...:
* want to run tools over a single file, or a specific subset of files,
independently of the build system
* want full control over the Clang AST
* want to share code with Clang Plugins
Do not use LibTooling when you...:
* want to run as part of the build triggered by dependency changes
* want a stable interface so you don't need to change your code when the AST API
changes
* want high level abstractions like cursors and code completion out of the box
* do not want to write your tools in C++
:doc:`Clang tools <ClangTools>` are a collection of specific developer tools
built on top of the LibTooling infrastructure as part of the Clang project.
They are targeted at automating and improving core development activities of
C/C++ developers.
Examples of tools we are building or planning as part of the Clang project:
* Syntax checking (:program:`clang-check`)
* Automatic fixing of compile errors (:program:`clang-fixit`)
* Automatic code formatting (:program:`clang-format`)
* Migration tools for new features in new language standards
* Core refactoring tools
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