CMake variable persisting between runs even though it was reset - build

Question

I'm trying to cross compile from Ubuntu to Windows, using CMake. I have everything configured (Installed both mingw32 and mingw64), and I have the relevant toolchain files for both. The problem is that a variable that I set in one toolchain file, after it is used, persists in the second run with the other toolchain file one as well.
These are my toolchain files:
Windows 64 bit: (Toolchain-Ubuntu-mingw64.cmake)
set(CMAKE_SYSTEM_NAME Windows)
unset(PROCESSOR_ARCHITECTURE CACHE)
set(PROCESSOR_ARCHITECTURE x64)
message("===Processor architecture: " ${PROCESSOR_ARCHITECTURE})
set(TOOLCHAIN_PREFIX x86_64-w64-mingw32)
set(CMAKE_C_COMPILER ${TOOLCHAIN_PREFIX}-gcc)
set(CMAKE_CXX_COMPILER ${TOOLCHAIN_PREFIX}-g++)
set(CMAKE_RC_COMPILER ${TOOLCHAIN_PREFIX}-windres)
set(CMAKE_FIND_ROOT_PATH /usr/${TOOLCHAIN_PREFIX})
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
Windows 32 bit: (Toolchain-Ubuntu-mingw32.cmake)
set(CMAKE_SYSTEM_NAME Windows)
unset(PROCESSOR_ARCHITECTURE CACHE)
set(PROCESSOR_ARCHITECTURE x86)
message("===Processor architecture: " ${PROCESSOR_ARCHITECTURE})
set(TOOLCHAIN_PREFIX i686-w64-mingw32)
set(CMAKE_C_COMPILER ${TOOLCHAIN_PREFIX}-gcc)
set(CMAKE_CXX_COMPILER ${TOOLCHAIN_PREFIX}-g++)
set(CMAKE_RC_COMPILER ${TOOLCHAIN_PREFIX}-windres)
set(CMAKE_FIND_ROOT_PATH /usr/${TOOLCHAIN_PREFIX})
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
And this is the top of my CMakeLists.txt file:
cmake_minimum_required(VERSION 2.8)
project("project")
set(SOURCE_FILE_LIST main.c)
set(ARCH_PROJECT_NAME ${PROJECT_NAME}${PROCESSOR_ARCHITECTURE})
message("Project - " ${ARCH_PROJECT_NAME})
...
When I run
cmake -DCMAKE_TOOLCHAIN_FILE=../cmake-toolchains/Toolchain-Ubuntu-mingw64.cmake ../src/
The output starts with:
===Processor architecture: x64
Project - projectx64
The unexpected part comes when I run:
cmake -DCMAKE_TOOLCHAIN_FILE=../cmake-toolchains/Toolchain-Ubuntu-mingw32.cmake ../src/
and the output still starts with
===Processor architecture: x64
Project - projectx64
What can I do to fix this behaviour?

Answer 1

CMake will cache many of the values it finds during the setup process. Frustratingly it does this to the point that attempting to recreate the projects with a new option specified on the command line simply doesn't work. The only solution I've found is to either delete the entire build directory, or the specific cache file in the build directory, called CMakeCache.txt I believe.