CMake Source Code Guide

The following is a guide to the CMake source code for developers. See documentation on CMake Development for more information.

C++ Code Style

We use clang-format version 6.0 to define our style for C++ code in the CMake source tree. See the .clang-format configuration file for our style settings. Use the Utilities/Scripts/clang-format.bash script to format source code. It automatically runs clang-format on the set of source files for which we enforce style. The script also has options to format only a subset of files, such as those that are locally modified.

C++ Subset Permitted

CMake requires compiling as C++11 or above. However, in order to support building on older toolchains some constructs need to be handled with care:

• Do not use std::auto_ptr.

  The std::auto_ptr template is deprecated in C++11. Use std::unique_ptr.

• Use CM_DISABLE_COPY(Class) to mark classes as non-copyable.

  The CM_DISABLE_COPY macro should be used in the private section of a class to make sure that attempts to copy or assign an instance of the class lead to compiler errors even if the compiler does not support deleted functions. As a guideline, all polymorphic classes should be made non-copyable in order to avoid slicing. Classes that are composed of or derived from non-copyable classes must also be made non-copyable explicitly with CM_DISABLE_COPY.

• Use size_t instead of std::size_t.

  Various implementations have differing implementation of size_t. When assigning the result of .size() on a container for example, the result should be assigned to size_t not to std::size_t, unsigned int or similar types.

Source Tree Layout

The CMake source tree is organized as follows.

• Auxiliary/: Shell and editor integration files.
• Help/: Documentation.
  • Help/dev/: Developer documentation.
  • Help/release/dev/: Release note snippets for development since last release.
• Licenses/: License files for third-party libraries in binary distributions.
• Modules/: CMake language modules installed with CMake.
• Packaging/: Files used for packaging CMake itself for distribution.
• Source/: Source code of CMake itself.
• Templates/: Files distributed with CMake as implementation details for generators, packagers, etc.
• Tests/: The test suite. See Tests/README.rst.
• Utilities/: Scripts, third-party source code.
  • Utilities/Sphinx/: Sphinx configuration to build CMake user documentation.
  • Utilities/Release/: Scripts used to package CMake itself for distribution on cmake.org.