# add\_subdirectory(foo system) doesn't work for me

**URL:** https://discourse.cmake.org/t/add-subdirectory-foo-system-doesnt-work-for-me/7063
**Category:** Usage
**Created:** [December 13, 2022, 2:55pm UTC](https://discourse.cmake.org/t/add-subdirectory-foo-system-doesnt-work-for-me/7063 "2022-12-13T14:55:05Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![gkodinov](https://discourse.cmake.org/user_avatar/discourse.cmake.org/gkodinov/32/2998_2.png) [@gkodinov](https://discourse.cmake.org/u/gkodinov)
#### Post date: [December 13, 2022, 2:55pm UTC](https://discourse.cmake.org/t/add-subdirectory-foo-system-doesnt-work-for-me/7063/1 "2022-12-13T14:55:05Z")

</div>

## I’m trying to add system subdirectories. my project is as follows: CMakeLists.txt

cmake\_minimum\_required(VERSION 3.5.1)  
PROJECT(test VERSION 0.0.0.1)  
ADD\_SUBDIRECTORY(b1 SYSTEM)  
ADD\_SUBDIRECTORY(b2 SYSTEM)  
ADD\_EXECUTABLE(m1 m1.cc)

## b1\CMakeLists.txt

ADD\_EXECUTABLE(b1 b1.cc)

## b2\CMakeLists.txt

ADD\_EXECUTABLE(b2 b2.cc)

## And when I run cmake on that I get:

```auto
cmake ..
-- Building for: Visual Studio 17 2022
-- Selecting Windows SDK version 10.0.19041.0 to target Windows 10.0.22000.
-- The C compiler identification is MSVC 19.34.31935.0
-- The CXX compiler identification is MSVC 19.34.31935.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: C:/Program Files/Microsoft Visual Studio/2022/Professional/VC/Tools/MSVC/14.34.31933/bin/Hostx64/x64/cl.exe - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: C:/Program Files/Microsoft Visual Studio/2022/Professional/VC/Tools/MSVC/14.34.31933/bin/Hostx64/x64/cl.exe - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at CMakeLists.txt:4 (ADD_SUBDIRECTORY):
  The binary directory

    C:/Users/gkodinov/dev/fix-warnings-trunk/gogo/bld/SYSTEM

  is already used to build a source directory. It cannot be used to build
  source directory

    C:/Users/gkodinov/dev/fix-warnings-trunk/gogo/b2

  Specify a unique binary directory name.

-- Configuring incomplete, errors occurred!
See also "C:/Users/gkodinov/dev/fix-warnings-trunk/gogo/bld/CMakeFiles/CMakeOutput.log".

```

---

<div class="post-metadata">

### Author: ![gkodinov](https://discourse.cmake.org/user_avatar/discourse.cmake.org/gkodinov/32/2998_2.png) [@gkodinov](https://discourse.cmake.org/u/gkodinov)
#### Post date: [December 13, 2022, 2:59pm UTC](https://discourse.cmake.org/t/add-subdirectory-foo-system-doesnt-work-for-me/7063/2 "2022-12-13T14:59:57Z")

</div>

Ok, I’ve got it. it’s a 3.25.1 feature.