# icx on Windows supports -external:I

**URL:** https://discourse.cmake.org/t/icx-on-windows-supports-external-i/8739
**Category:** Development
**Tags:** comp:intel
**Created:** [August 15, 2023, 1:51pm UTC](https://discourse.cmake.org/t/icx-on-windows-supports-external-i/8739 "2023-08-15T13:51:10Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![FROMAGMA](https://discourse.cmake.org/letter_avatar_proxy/v4/letter/f/bbce88/32.png) [@FROMAGMA](https://discourse.cmake.org/u/FROMAGMA)
#### Post date: [August 15, 2023, 1:51pm UTC](https://discourse.cmake.org/t/icx-on-windows-supports-external-i/8739/1 "2023-08-15T13:51:11Z")

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Hi,

We use Intel oneAPI 2023.2.0 on Windows with VS2019 installed and found out that icx supports the -external:I option for suppressing warnings from includes which came from these paths.  
We use Ninja generator on Windows.  
Unfortunately we have to set manually  
set ( CMAKE\_INCLUDE\_SYSTEM\_FLAG\_C -external:I )  
set ( CMAKE\_INCLUDE\_SYSTEM\_FLAG\_CXX -external:I )  
since these are empty after CMake configure.

So I would ask if this can be fixed in CMake the future.

Best regards  
Frank

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### Author: ![ben.boeckel](https://discourse.cmake.org/letter_avatar_proxy/v4/letter/b/ea5d25/32.png) [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [August 15, 2023, 4:40pm UTC](https://discourse.cmake.org/t/icx-on-windows-supports-external-i/8739/2 "2023-08-15T16:40:13Z")

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Is 2023.2.0 when they introduced the flag? I suppose the version check can be adapted in the future if it turns out to be too high.

[https://gitlab.kitware.com/cmake/cmake/-/merge\_requests/8722](https://gitlab.kitware.com/cmake/cmake/-/merge_requests/8722)