# Error while Cross-compiling a cmake project

**URL:** <https://forum.openwrt.org/t/error-while-cross-compiling-a-cmake-project/104504>\
**Category:** For Developers\
**Created:** [August 24, 2021, 6:33pm UTC](https://forum.openwrt.org/t/error-while-cross-compiling-a-cmake-project/104504 "2021-08-24T18:33:00Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![hela.essouri](https://forum.openwrt.org/letter_avatar/hela.essouri/32/5_5575768a8748004e209b776fc1b2916d.png) [@hela.essouri](https://forum.openwrt.org/u/hela.essouri)\
**Post date:** [August 24, 2021, 6:33pm UTC](https://forum.openwrt.org/t/error-while-cross-compiling-a-cmake-project/104504/1 "2021-08-24T18:33:00Z")

</div>

Hello,  
I am trying to cross compile a project using cmake, I am running:

```
$ mkdir build
$ cd build
$ cmake .. -DCMAKE_CXX_COMPILER=x86_64-openwrt-linux-musl-g++ -DCMAKE_INSTALL_PREFIX=/usr -DSYSINSTALL_BINDINGS=ON -DBUILD_GO=OFF -DBUILD_PYTHON=OFF -DBUILD_RUBY=OFF -DBUILD_EXAMPLES=OFF

```

But I am getting this error:

```
-- The C compiler identification is GNU 7.5.0
-- The CXX compiler identification is unknown
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
CMake Error at CMakeLists.txt:5 (project):
  The CMAKE_CXX_COMPILER:

    x86_64-openwrt-linux-musl-g++

  is not a full path and was not found in the PATH.

  Tell CMake where to find the compiler by setting either the environment
  variable "CXX" or the CMake cache entry CMAKE_CXX_COMPILER to the full path
  to the compiler, or to the compiler name if it is in the PATH.

-- Configuring incomplete, errors occurred!

```

The CMakeErrorLog file shows:

```
The output was:
No such file or directory

Compiling the CXX compiler identification source file "CMakeCXXCompilerId.cpp" failed.
Compiler: x86_64-openwrt-linux-musl-g++ 
Build flags: 
Id flags: -c 

The output was:
No such file or directory

Compiling the CXX compiler identification source file "CMakeCXXCompilerId.cpp" failed.
Compiler: x86_64-openwrt-linux-musl-g++ 
Build flags: 
Id flags: --c++ 

The output was:
No such file or directory

Compiling the CXX compiler identification source file "CMakeCXXCompilerId.cpp" failed.
Compiler: x86_64-openwrt-linux-musl-g++ 
Build flags: 
Id flags: --ec++ 

The output was:
No such file or directory

```

I tried to change the cmake file and add CXX path:

```
set(CMAKE_CXX_COMPILER "/usr/bin/g++")

```

But I got another error:

```
-- The C compiler identification is GNU 7.5.0
-- The CXX compiler identification is GNU 7.5.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/g++
-- Check for working CXX compiler: /usr/bin/g++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
You have changed variables that require your cache to be deleted.
Configure will be re-run and you may have to reset some variables.
The following variables have changed:
CMAKE_CXX_COMPILER= x86_64-openwrt-linux-musl-g++

```

Any idea how to fix this compiler issue please?  
Thanks