# Include guards in toolchain files

**URL:** https://discourse.cmake.org/t/include-guards-in-toolchain-files/3376
**Category:** Usage
**Created:** [May 20, 2021, 12:54pm UTC](https://discourse.cmake.org/t/include-guards-in-toolchain-files/3376 "2021-05-20T12:54:12Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![petwu](https://discourse.cmake.org/user_avatar/discourse.cmake.org/petwu/32/1399_2.png) [@petwu](https://discourse.cmake.org/u/petwu)
#### Post date: [May 20, 2021, 12:54pm UTC](https://discourse.cmake.org/t/include-guards-in-toolchain-files/3376/1 "2021-05-20T12:54:12Z")

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I recently came accross some (rare) examples/code snippets, where the `include_guard([GLOBAL])` command is used inside a toolchain file, e.g. [[1]](https://www.qt.io/blog/standalone-boot2qt-/-yocto-sdk-cmake-toolchain), [[2]](https://gitlab.kitware.com/cmake/cmake/-/issues/22125), [[3]](https://github.com/conan-io/conan/blob/1.36.0/conan/tools/cmake/toolchain.py#L528).

I understand the general purpose of include guards in modules, but I am unsure if they are useful or misplaced in toolchain files. As far as I know the toolchain is intentionally processed multiple times every time a new language gets enabled by a `project()` or `enable_language()` call. This made me wonder, if an include guard could possibly cause problems?

I would appreciate if someone with more expertise regarding toolchains could explain to me possible advantages/disadvantages/pitfalls and if using include guards in toolchain files is considered a good/valid thing to do or if it is discouraged.

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### Author: ![gabyx](https://discourse.cmake.org/user_avatar/discourse.cmake.org/gabyx/32/2107_2.png) [@gabyx](https://discourse.cmake.org/u/gabyx)
#### Post date: [May 5, 2022, 6:06am UTC](https://discourse.cmake.org/t/include-guards-in-toolchain-files/3376/2 "2022-05-05T06:06:29Z")

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Would be interessted too

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### Author: ![buildSystemPerson](https://discourse.cmake.org/user_avatar/discourse.cmake.org/buildsystemperson/32/2851_2.png) [@buildSystemPerson](https://discourse.cmake.org/u/buildSystemPerson)
#### Post date: [May 31, 2025, 5:30am UTC](https://discourse.cmake.org/t/include-guards-in-toolchain-files/3376/3 "2025-05-31T05:30:05Z")

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In this issue it looks like adding an include\_guard in your toolchain file can cause an issue:  
[https://gitlab.kitware.com/cmake/cmake/-/issues/25239](https://gitlab.kitware.com/cmake/cmake/-/issues/25239)