Must CLANG be in System Path when using cmake and Visual Studio? - cmake

Question

I want to use
Visual Studio 2022
CMakeLists.txt based project
LLVM and C++
To be able to have for future multiple Clang Versions in parallel on my HardDrive (e.g. Support of older projects), I do not want to add Clang to my system path.
If I run that setup in the command line it works without having to add CLANG to my system path. But it does not in Visual Studio
The current setup for Visual Studio works with a batch file adding the Clang Path to the current System Path and starting Visual Studio afterward.
Here is my current CMakeLists.txt
cmake_minimum_required(VERSION 3.10)
set(PROJECT_ROOT "${CMAKE_CURRENT_SOURCE_DIR}/../../..")
set(CMAKE_PREFIX_PATH "${PROJECT_ROOT}/tools/compiler/LLVM/bin")
# Check if the compiler is available in the expected directory
find_path(COMPILER_DIR
NAMES clang.exe
)
# Check if the compiler was found
IF( IS_DIRECTORY "${COMPILER_DIR}")
# We want to choose the compiler used for this project
# This works only if the set is done before the project() call
set(CMAKE_C_COMPILER ${COMPILER_DIR}/clang.exe CACHE PATH "" FORCE)
set(CMAKE_CXX_COMPILER ${COMPILER_DIR}/clang++.exe CACHE PATH "" FORCE)
ELSE()
MESSAGE(STATUS "Compiler directory not found")
ENDIF()
project(runUnitTests)
# removed some lines ...
set(GTEST "${PROJECT_ROOT}/tools/googletest-main")
set(COMMON "${PROJECT_ROOT}/common")
# ----======================================================================----
add_definitions(-DINLINE=inline)
add_definitions(-DUNIT_TEST)
add_definitions(-DGTEST_USE_OWN_TR1_TUPLE)
# Prevent overriding the parent project's compiler/linker
# settings on Windows
set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
# ----======================================================================----
# GTest.
# ----======================================================================----
# enable CMake’s test runner to discover the tests included in the binary,
# using the GoogleTest CMake module.
include(GoogleTest)
# add the google test directory as a subdirectory
# by this it gets automatically build and the libraries are put into the "out" directory
add_subdirectory(${GTEST} out)
# Add include directories
include_directories(
${CMAKE_CURRENT_SOURCE_DIR}
${GTEST}/googletest/include
${GTEST}/googlemock/include
# removed some lines ...
)
# ----======================================================================----
# Headers.
# ----======================================================================----
file(GLOB_RECURSE ${PROJECT_NAME}_HEADERS "*.h" "*.hpp")
# ----======================================================================----
# Sources.
# ----======================================================================----
# Main Sources
set(SOURCES
# removed some lines ...
./main_pc.cpp
)
# additional source files
set(ADDITIONAL_SOURCES
# Please add here the source files needed for your test
./sampleClass.cpp
)
# Test case source files
set(TEST_SOURCES
# Please add here your own test case files
./test_sampleClass.cpp
)
# ----======================================================================----
# Executable setup
# ----======================================================================----
# Test without matlab libraries
add_executable(${PROJECT_NAME} ${SOURCES} ${ADDITIONAL_SOURCES} ${TEST_SOURCES} ${${PROJECT_NAME}_HEADERS})
# add the gtest/gmock library to the linker
target_link_libraries(${PROJECT_NAME} gtest gmock)
# This is so you can do 'make test' to see all your tests run, instead of
# manually running the executable runUnitTests to see those specific tests.
add_test(NAME allTests COMMAND runUnitTests)
# Check if the teamcity envoirnment variable is set
# Because when running on teamcity the gtest_discover_tests call fails
# But this is needed that the Visual Studio Test Explorer can detect the test cases.
if(NOT DEFINED ENV{TEAMCITY_VERSION})
enable_testing()
# since CMake 3.10 it is possible to scan the test executable for test
# This is needed that Visual Studio Test Explorer is able to display the test cases
gtest_discover_tests(${PROJECT_NAME})
endif(NOT DEFINED ENV{TEAMCITY_VERSION})
and here is my CMakeSettings.json
{
"configurations": [
{
"name": "x86-Debug",
"generator": "Ninja",
"configurationType": "Debug",
"inheritEnvironments": [ "clang_cl_x86" ],
"buildRoot": "${projectDir}\\out\\build\\${name}",
"installRoot": "${projectDir}\\out\\install\\${name}",
"cmakeCommandArgs": "",
"buildCommandArgs": "",
"ctestCommandArgs": ""
}
]
}
Error message in Visual Studio if Clang is not in Path:
1> CMakeSettings Error at CMakeSettings.json: Failed to load configuration 'x86-Debug'. Enable Cross Platform Logging for more information.
1> Failed to load configuration 'x86-Debug'. Enable Cross Platform Logging for more information.
1> Failed to load configuration 'x86-Debug'. Enable Cross Platform Logging for more information.
I enabled "Cross Platform Logging" but it is empty.
Tried also to set absolute paths in CMakeLists to CLANG. Did not change the situation.
When I run Visual Studio once with CLang in the Path and compile the project -> it works on the next start for Visual Studio that Clang is NOT in the PATH. When I delete the "out" folder, back to failing.