CodeQL code scanning for compiled languages

About the CodeQL analysis workflow and compiled languages

Code scanning works by running queries against one or more databases. Each database contains a representation of all of the code in a single language in your repository. For the compiled languages C/C++, C#, and Java, the process of populating this database involves building the code and extracting data.

CodeQL analyzes the C/C++, C#, and Java source files in your repository that are built.

The basic CodeQL analysis workflow uses the autobuild action to build your code. Alternatively, you can disable autobuild and instead specify explicit build commands to analyze only the files that are built by these custom commands.

You set up GitHub to run code scanning for your repository by adding a GitHub Actions workflow to the repository. For CodeQL code scanning, you add the CodeQL analysis workflow. For more information, see "Configuring code scanning."

For information about the languages, libraries, and frameworks that are supported in the latest version of CodeQL, see "Supported languages and frameworks" in the CodeQL documentation. For information about the system requirements for running the latest version of CodeQL, see "System requirements" in the CodeQL documentation.

If your workflow uses a language matrix, autobuild attempts to build each of the compiled languages listed in the matrix. Without a matrix autobuild attempts to build the supported compiled language that has the most source files in the repository. With the exception of Go, analysis of other compiled languages in your repository will fail unless you supply explicit build commands.

About autobuild for CodeQL

CodeQL analyzes the C/C++, C#, and Java source files in your repository that are built.

The basic CodeQL analysis workflow uses the autobuild action to build your code. Alternatively, you can disable autobuild and instead specify explicit build commands to analyze only the files that are built by these custom commands.

• autobuild for C/C++
• autobuild for C#
• autobuild for Java

autobuild for C/C++

Supported system type	System name
Operating system	Windows, macOS, and Linux
Build system	Windows: MSbuild and build scripts Linux and macOS: Autoconf, Make, CMake, qmake, Meson, Waf, SCons, Linux Kbuild, and build scripts

The behavior of the autobuild step varies according to the operating system that the extraction runs on. On Windows, the autobuild step attempts to autodetect a suitable build method for C/C++ using the following approach:

1. Invoke MSBuild.exe on the solution (.sln) or project (.vcxproj) file closest to the root. If autobuild detects multiple solution or project files at the same (shortest) depth from the top level directory, it will attempt to build all of them.
2. Invoke a script that looks like a build script—build.bat, build.cmd, and build.exe (in that order).

On Linux and macOS, the autobuild step reviews the files present in the repository to determine the build system used:

1. Look for a build system in the root directory.
2. If none are found, search subdirectories for a unique directory with a build system for C/C++.
3. Run an appropriate command to configure the system.

For self-hosted runners, you will likely need to install the gcc compiler, and specific projects may also require access to clang or msvc executables. You will also need to install the build system (for example msbuild, make, cmake, bazel) and utilities (such as python, perl, lex, and yacc) that your projects depend on.

autobuild for C#

Supported system type	System name
Operating system	Windows, macOS, and Linux
Build system	.NET and MSbuild, as well as build scripts

The autobuild process attempts to autodetect a suitable build method for C# using the following approach:

1. Invoke dotnet build on the solution (.sln) or project (.csproj) file closest to the root.
2. Invoke MSbuild (Linux) or MSBuild.exe (Windows) on the solution or project file closest to the root. If autobuild detects multiple solution or project files at the same (shortest) depth from the top level directory, it will attempt to build all of them.
3. Invoke a script that looks like a build script—build and build.sh (in that order, for Linux) or build.bat, build.cmd, and build.exe (in that order, for Windows).

For .NET Core application development on self-hosted runners, the .NET SDK is required (for dotnet).

For .NET Framework application development, on Windows, you will need Microsoft Build Tools (for msbuild) and Nuget CLI (for nuget). On Linux and macOS, you will require Mono Runtime (to run mono, msbuild, or nuget).

autobuild for Java

Supported system type	System name
Operating system	Windows, macOS, and Linux (no restriction)
Build system	Gradle, Maven and Ant

The autobuild process tries to determine the build system for Java codebases by applying this strategy:

1. Search for a build file in the root directory. Check for Gradle then Maven then Ant build files.
2. Run the first build file found. If both Gradle and Maven files are present, the Gradle file is used.
3. Otherwise, search for build files in direct subdirectories of the root directory. If only one subdirectory contains build files, run the first file identified in that subdirectory (using the same preference as for 1). If more than one subdirectory contains build files, report an error.

If you're using self-hosted runners, the required version(s) of Java should be present:

• If the runner will be used for analyzing repositories that need a single version of Java, then the appropriate JDK version needs to be installed, and needs to be present in the PATH variable (so that java and javac can be found).

• If the runner will be used for analyzing repositories that need multiple versions of Java, then the appropriate JDK versions need to be installed, and can be specified via the toolchains.xml file. This is a configuration file, typically used by Apache Maven, that allows you to specify the location of the tools, the version of the tools, and any additional configuration that is required to use the tools. For more information, see "Guide to Using Toolchains" in the Apache Maven documentation.

The following executables will likely be required for a range of Java projects, and should be present in the PATH variable, but they will not be essential in all cases:

• mvn (Apache Maven)
• gradle (Gradle)
• ant (Apache Ant)

You will also need to install the build system (for example make, cmake, bazel) and utilities (such as python, perl, lex, and yacc) that your projects depend on.

Adding build steps for a compiled language

If autobuild fails, or you want to analyze a different set of source files from those built by the autobuild process, you'll need to remove the autobuild step from the workflow, and manually add build steps. For C/C++, C#, Go, and Java projects, CodeQL will analyze whatever source code is built by your specified build steps. For information on how to edit the workflow file, see "Customizing code scanning."

After removing the autobuild step, uncomment the run step and add build commands that are suitable for your repository. The workflow run step runs command-line programs using the operating system's shell. You can modify these commands and add more commands to customize the build process.

- run: |
    make bootstrap
    make release

For more information about the run keyword, see "Workflow syntax for GitHub Actions."

If your repository contains multiple compiled languages, you can specify language-specific build commands. For example, if your repository contains C/C++, C# and Java, and autobuild correctly builds C/C++ and C# but fails to build Java, you could use the following configuration in your workflow, after the init step. This specifies build steps for Java while still using autobuild for C/C++ and C#:

- if: matrix.language == 'cpp' || matrix.language == 'csharp'
  name: Autobuild
  uses: github/codeql-action/autobuild@v2
- if: matrix.language == 'java'
  name: Build Java
  run: |
    make bootstrap
    make release

For more information about the if conditional, see "Workflow syntax for GitHub Actions."

For more tips and tricks about why autobuild won't build your code, see "Automatic build failed for a compiled language."

If you added manual build steps for compiled languages and code scanning is still not working on your repository, contact your site administrator.