Added VS Code devcontainer and uptaded needed llvm versionn to 14.

.devcontainer/Dockerfile

@@ -0,0 +1,12 @@
+# See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.241.1/containers/ubuntu/.devcontainer/base.Dockerfile
+
+# [Choice] Ubuntu version (use ubuntu-22.04 or ubuntu-18.04 on local arm64/Apple Silicon): ubuntu-22.04, ubuntu-20.04, ubuntu-18.04
+ARG VARIANT="jammy"
+FROM mcr.microsoft.com/vscode/devcontainers/base:0-${VARIANT}
+
+# [Optional] Uncomment this section to install additional OS packages.
+RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
+     && apt-get -y install --no-install-recommends \
+     llvm llvm-dev clang lldb gcc gdb cmake make ninja-build
+
+ENV LLVM_DIR=/usr/lib/llvm-14

.devcontainer/devcontainer.json

@@ -0,0 +1,30 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the README at:
+// https://github.com/microsoft/vscode-dev-containers/tree/v0.241.1/containers/ubuntu
+{
+	"name": "Ubuntu",
+	"build": {
+		"dockerfile": "Dockerfile",
+		// Update 'VARIANT' to pick an Ubuntu version: jammy / ubuntu-22.04, focal / ubuntu-20.04, bionic /ubuntu-18.04
+		// Use ubuntu-22.04 or ubuntu-18.04 on local arm64/Apple Silicon.
+		"args": { "VARIANT": "ubuntu-22.04" }
+	},
+	"extensions": ["llvm-vs-code-extensions.vscode-clangd",
+		"matepek.vscode-catch2-test-adapter",
+		"twxs.cmake",
+		"vadimcn.vscode-lldb",
+		"xaver.clang-format"
+		],
+
+	// Use 'forwardPorts' to make a list of ports inside the container available locally.
+	// "forwardPorts": [],
+
+	// Use 'postCreateCommand' to run commands after the container is created.
+	// "postCreateCommand": "uname -a",
+
+	// Comment out to connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
+	"remoteUser": "vscode",
+	"features": {
+		"git": "latest",
+		"fish": "latest"
+	}
+}

CMakeLists.txt

@@ -59,10 +59,10 @@ endif()
 # `find_package(llvm)`. So there's no need to add it here.
 list(APPEND CMAKE_PREFIX_PATH "${LT_LLVM_INSTALL_DIR}/lib/cmake/llvm/")
 
-find_package(LLVM 13.0.0 REQUIRED CONFIG)
+find_package(LLVM 14.0.0 REQUIRED CONFIG)
 
 # Another sanity check
-if(NOT "13" VERSION_EQUAL "${LLVM_VERSION_MAJOR}")
+if(NOT "14" VERSION_EQUAL "${LLVM_VERSION_MAJOR}")
   message(FATAL_ERROR "Found LLVM ${LLVM_VERSION_MAJOR}, but need LLVM 13")
 endif()