README.md

pre-commit hooks

This is a pre-commit hooks repo that integrates two C/C++ code formatters:

clang-format, uncrustify,

and five C/C++ static code analyzers:

clang-tidy, oclint, cppcheck, cpplint, include-what-you-use

This repo's hooks do more than passthrough arguments to provide these features:

• Relay correct pass/fail to pre-commit, even when some commands exit 0 when they should not. Some versions of oclint, clang-tidy, and cppcheck have this behavior.
• Honor -- arguments, which pre-commit has problems with
• Optionally enforce a command version so your team gets code formatted/analyzed the same way
• Formatters clang-format and uncrustify will error with diffs of what has changed

Example Usage

With this err.c

#include <stdio.h>
int main(){int i;return;}

and using this .pre-commit-config.yaml:

fail_fast: false
repos:
  - repo: https://github.com/pocc/pre-commit-hooks
    rev: master
    hooks:
      - id: clang-format
        args: [--style=Google]
      - id: clang-tidy
      - id: oclint
      - id: uncrustify
      - id: cppcheck
      - id: cpplint
      - id: include-what-you-use

All seven linters should fail on commit with these messages. Full text is at media/all_failed.txt.

clang-format error (indentation)

clang-format.............................................................Failed
- hook id: clang-format
- exit code: 1

err.c
====================
--- original

+++ formatted

@@ -1,3 +1,6 @@

 #include <stdio.h>
-int main(){int i;return;}
+int main() {
+  int i;
+  return;
+}

clang-tidy error (non-void main should return a value)

clang-tidy...............................................................Failed
- hook id: clang-tidy
- exit code: 1

/tmp/temp/err.c:2:18: error: non-void function 'main' should return a value [clang-diagnostic-return-type]
int main(){int i;return;}
                 ^
1 error generated.
Error while processing /tmp/temp/err.c.
Found compiler error(s).

oclint error (non-void main should return a value)

oclint...................................................................Failed
- hook id: oclint
- exit code: 6

Compiler Errors:
(please be aware that these errors will prevent OCLint from analyzing this source code)

/tmp/temp/err.c:2:18: non-void function 'main' should return a value

Clang Static Analyzer Results:

/tmp/temp/err.c:2:18: non-void function 'main' should return a value


OCLint Report

Summary: TotalFiles=0 FilesWithViolations=0 P1=0 P2=0 P3=0


[OCLint (https://oclint.org) v21.05]

uncrustify error (indentation)

uncrustify...............................................................Failed
- hook id: uncrustify
- exit code: 1

err.c
====================
--- original

+++ formatted

@@ -1,3 +1,5 @@

 #include <stdio.h>
-int main(){int i;return;}
+int main(){
+  int i; return;
+}

cppcheck error (unused variable i)

cppcheck.................................................................Failed
- hook id: cppcheck
- exit code: 1

err.c:2:16: style: Unused variable: i [unusedVariable]
int main(){int i;return;}
               ^

cpplint error (no copyright message, bad whitespace)

cpplint..................................................................Failed
- hook id: cpplint
- exit code: 1

Done processing err.c
Total errors found: 4
err.c:0:  No copyright message found.  You should have a line: "Copyright [year] <Copyright Owner>"  [legal/copyright] [5]
err.c:2:  More than one command on the same line  [whitespace/newline] [0]
err.c:2:  Missing space after ;  [whitespace/semicolon] [3]
err.c:2:  Missing space before {  [whitespace/braces] [5]

include-what-you-use error (remove unused #include )

include-what-you-use.....................................................Failed
- hook id: include-what-you-use
- exit code: 3

err.c:2:18: error: non-void function 'main' should return a value [-Wreturn-type]
int main(){int i;return;}
                 ^

err.c should add these lines:

err.c should remove these lines:
- #include <stdio.h>  // lines 1-1

The full include-list for err.c:
---

Note that for your config yaml, you can supply your own args or remove the args line entirely, depending on your use case.

You can also clone this repo and then run the test_repo to see all of the linters at work to produce this output:

git clone https://github.com/pocc/pre-commit-hooks
cp -r pre-commit-hooks/tests/test_repo .
cd test_repo
git init
git add .
pre-commit run

Note that we are copying the test_repo outside of the pre-commit-hooks repo so that pre-commit doesn't get confused by nested github repositories.

Using this repo

Special flags in this repo

There are 2 flags, --version and --no-diff that can be added to args: for a pre-commit hook. They will be removed and not be passed on to the command.

Some linters change behavior between versions. To enforce a linter version 8.0.0, for example, add --version=8.0.0 to args: for that linter. Note that this is a pre-commit hook arg and will be filtered before args are passed to the linter.

You can add --no-diff to the args: for clang-format and uncrustify if you would like there to be no diff output for these commands.

Default Options

These options are automatically added to enable all errors or are required.

• oclint: ["-enable-global-analysis", "-enable-clang-static-analyzer", "-max-priority-3", "0"]
• uncrustify: ["-c", "defaults.cfg", "-q"] (options added, and a defaults.cfg generated, if -c is missing)
• cppcheck: ["-q" , "--error-exitcode=1", "--enable=all", "--suppress=unmatchedSuppression", "--suppress=missingIncludeSystem", "--suppress=unusedFunction"] (See #30)
• cpplint: ["--verbose=0"]

If you supply any of these options in args:, your options will override the above defaults (use -<flag>=<option> if possible when overriding).

Compilation Database

clang-tidy and oclint both expect a compilation database. Both of the hooks for them will ignore the error for not having one.

You can generate with one cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON <dir> if you have a cmake-based project.

Information about the Commands

Python3.6+ is required to use these hooks as all 5 invoking scripts are written in it. As this is also the minimum version of pre-commit, this should not be an issue.

Installation

Use these commands to install some or all of the linters used in this project:

• Linux
  • brew install llvm uncrustify cppcheck include-what-you-use [1] [2]
  • oclint: See note below for installation [3]
• MacOS
  • brew install llvm uncrustify cppcheck include-what-you-use oclint
• Windows
  • choco install llvm uncrustify cppcheck inlcude-what-you-use
• Cross-platform
  • pip install cpplint
  • pipx install clang-format [4]

[1]: llvm includes tools like clang-format and clang-tidy.

[2]: While it's possible to use other package managers to install these utilities on Linux, I recommend using brew to avoid dependency issues between llvm and linters that use it, such as include-what-you-use.

[3]: You can install on MacOS with brew install oclint. Oclint's github page also provides compiled binary packages (and zip of source code to compile) for Macos/Linux: releases. oclint is not available on windows.

[4]: This will download the latest version. Versions from 10.0.1 and up are supported. To pin to a specific version like 13.0.0, use pipx install clang-format==13.0.0. Check out the clang-format-wheel repository for information on how to download the clang-format binary as part of a CI pre-commit build.

Hook Info

Hook Info	Type	Languages
clang-format	Formatter	C, C++, ObjC, ObjC++, Java
clang-tidy	Static code analyzer	C, C++, ObjC
oclint	Static code analyzer	C, C++, ObjC
uncrustify	Formatter	C, C++, C#, ObjC, D, Java, Pawn, Vala
cppcheck	Static code analyzer	C, C++
cpplint	Style checker	C, C++
include-what-you-use	Static code analyzer	C, C++

Hook Option Comparison

Hook Options	Fix In Place	Enable all Checks	Set key/value
clang-format	-i
clang-tidy	--fix-errors [1]	-checks=* -warnings-as-errors=* [2]
oclint		-enable-global-analysis -enable-clang-static-analyzer -max-priority-3 0 [3]	-rc=<key>=<value>
uncrustify	--replace --no-backup [4]		--set key=value
cppcheck		-enable=all
cpplint		--verbose=0
include-what-you-use		--verbose=3

[1]: -fix will fail if there are compiler errors. -fix-errors will -fix and fix compiler errors if it can, like missing semicolons.

[2]: Be careful with -checks=*. can have self-contradictory rules in newer versions of llvm (9+): modernize wants to use trailing return type but Fuchsia disallows it. Thanks to @rambo.

[3]: The oclint pre-commit hook does the equivalent of -max-priority-3 0 by default, which returns an error code when any check fails. See oclint error codes for more info on partially catching failed checks.

[4]: By definition, if you are using pre-commit, you are using version control. Therefore, it is recommended to avoid needless backup creation by using --no-backup.

Development

See README_dev.md

Additional Resources

clang-format

• Official Docs
• clang-format Guide - a good overview and a great place to get started
• clang-format Configurator - Website to interactively design your config while
• clang-format Options Explorer - Website to interactively understand various options
• Source Code

clang-tidy

• Official Docs
• clang-tidy guide - Good place to start
• Example usage - Explanation of how to use clang-tidy by the creators of Kratos
• Add your own checks - Function names must be awesome!
• Source Code

oclint

• Official Docs
• Fastlane Integration
• Source Code

uncrustify

• Official Docs
• Getting Started with Uncrustify
• Source Code

cppcheck

• Official Docs
• Using Cppcheck
• Source Code

cpplint

• Google C++ style guide (basis of cpplint)
• Source Code

include-what-you-use

• Official Docs
• Using include-what-you-use
• Source Code

License

Apache 2.0