CMake does not support toolset specification - cmake

Question

I'm trying to build the Checked-C project which uses CMake, but when I go to generate the makefile CMake gives the following error.
~/checkedc/build$ cmake ../llvm
CMake Error at CMakeLists.txt:57 (project):
Generator
Unix Makefiles
does not support toolset specification, but toolset
host=x64
was specified.
-- Configuring incomplete, errors occurred!
I have CMake version 3.9.1 installed along with GNU Make 4.1, Clang 5, and GCC 7. Anyone able to tell me what this CMake error means?
That section of CMakeLists.txt looks like this:
57 project(LLVM
58 ${cmake_3_0_PROJ_VERSION}
59 ${cmake_3_0_LANGUAGES}
60 C CXX ASM)
I've tried setting C/CXX/ASM but get the same error:
~/checkedc/build$ cmake -DCMAKE_C_COMPILER="clang-5.0" -DCMAKE_CXX_COMPILER="clang-5.0" -DCMAKE_ASM_COMPILER="clang-5.0" ../llvm
CMake Error at CMakeLists.txt:57 (project):
Generator
Unix Makefiles
does not support toolset specification, but toolset
host=x64
was specified.
-- Configuring incomplete, errors occurred!
I'm on Kubuntu 17.10 64bit.

Answer 1

It means that somewhere CMake file the variable CMAKE_GENERATOR_TOOLSET is set to host=x64. This only makes sense for Visual Studio generator so CMake opts to throw an error in this case.
To fix it double check the setup for your OS and generator. If this doesn't help then you'll need to find where this variable is set and remove this line.

Answer 2

I have the same issue - how I fixed it in my case. Indeed, I had copied the setup for cmake from windows then ported to Linux. When you run the first time, it will create in the build directory a file called: CMakeCache.txt. This file keeps some variables set initially for Windows. I removed it, together with all the CMakeFiles directory and rerun the cmake command to generate the project. It was working perfectly, but I had to set the CMAKE_CXX_COMPILER and CMAKE_C_COMPILER variables to the cmake command: -DCMAKE_CXX_COMPILER=/usr/bin/g++ -DCMAKE_C_COMPILER=/usr/bin/gcc
Hope it is working for you too.