clang-tidy plugin demo

This repository contains the slides for the Large Scale Refactoring using Clang-Tidy presentation that was presented at Montréal C++ Meetup on November 24th 2022.

The code for the custom Clang-Tidy check is in the src/custom_check folder.

The sample code used during the presentation is in the src/sample_code_for_presentation folder.

The slide deck is available here.

Quick Start

To compile the custom Clang-Tidy check used in the presentation, you need clang-tidy-14 (or more recent) installed on your machine.

1a. Easy Setup

On a an OS that packages clang-tidy-14 (like Ubuntu 22.04), you could perform the following commands to install the required packages:

sudo apt update
sudo apt install cmake clang-14 clang-tidy-14 libclang-14-dev

1b. More Involved Setup

You could install clang-tidy from the source code. See https://github.com/coveooss/clang-tidy-plugin-example for more information on how to do this.

2. Compile the custom Clang-Tidy plugin

Use this command if you install Clang-Tidy from packages:

cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER=/usr/bin/clang++-14 -B build -S .
cmake --build build

You will have to change the path to the compiler if you built Clang from the source code.

3. Check that the custom plugin can be loaded by Clang-Tidy

Enter the following command to see if the custom check is in the list of all checks:

clang-tidy-14 --checks=* --load build/lib/libReviseLibV2Check.so --list-checks | grep revise

If the plugin is working, you should see revise-libv2-api in the console.

4. Commands used in the presentation

Clang-Tidy requires a compilation database (a compile_commands.json file) to work properly. When building the code step 2 above, we used the ./build folder. Because of this, we must add the option -p build to the clang-tidy command-line options to specify where the compile_commands.json file could be found.

In the presentation the full path to the sample files (src/sample_code_for_presentation/) was not given.

In the presentation we removed the -*, at the beginning of the --checks option. This is needed to disable all other checks.

Here is the detailed list of commands that were used durring the presentation:

clang-tidy-14 --checks="-*,bugprone*" -p build src/sample_code_for_presentation/example1.cpp
clang-tidy-14 --checks="-*,modernize-loop-convert" -p build --fix src/sample_code_for_presentation/example2.cpp
clang-tidy-14 --checks="performance-*" -p build --fix src/sample_code_for_presentation/example3.cpp
run-clang-tidy-14 -export-fixes=fixes.yaml -p build
clang-apply-replacements-14 .
clang-14 -cc1 -ast-dump src/sample_code_for_presentation/patate.cpp
clang-query-14 -p build src/sample_code_for_presentation/example4.cpp
clang-tidy-14 --checks=-*,revise-* -p build --load build/lib/libReviseLibV2Check.so src/sample_code_for_presentation/example4.cpp
clang-tidy-14 --checks=-*,revise-* -p build --load build/lib/libReviseLibV2Check.so --fix src/sample_code_for_presentation/example4.cpp

Thanks

Thanks to Stephen Kelly for writing his amazing Exploring Clang Tooling blog in 2018. This help a lot demystifying how to write custom Clang-Tidy checks. References to his blog and videos are available at the end of the slide deck.

Thanks to Kevin Lalumière for his work on how to build a Clang-Tidy check in a plugin (dynamic-link library). See his clang-tidy plugins project for details.