[Bug] Incorrect escaping of semicolons in cmake.configureSettings

[kaladron]

Brief Issue Summary

When performing a CMake configure, cmake-tools incorrectly escapes semicolons. When setting up LLVM:

{
  "cmake.sourceDirectory": "${workspaceFolder}/runtimes",
  "cmake.configureSettings": {
      "LLVM_ENABLE_RUNTIMES" : "libc;compiler-rt",
      "LLVM_LIBC_FULL_BUILD" : true
  }
}

cmake-tools will configure with "-DLLVM_ENABLE_RUNTIMES:STRING=libc\;compiler-rt". However, it is unnecessary to escape the semicolon because the whole parameter is enclosed in quotes. The result is that the semicolon is passed through to CMake erroneously.

From the CMakeCache.txt file:

LLVM_ENABLE_RUNTIMES:STRING=libc\;compiler-rt

CMake Tools Diagnostics

{
  "os": "linux",
  "vscodeVersion": "1.104.3",
  "cmtVersion": "1.21.36",
  "configurations": [
    {
      "folder": "/workspaces/llvm-project",
      "cmakeVersion": "4.1.2",
      "configured": true,
      "generator": "Ninja",
      "usesPresets": false,
      "compilers": {
        "C": "/usr/bin/clang",
        "CXX": "/usr/bin/clang++"
      }
    }
  ],
  "cpptoolsIntegration": {
    "isReady": false,
    "hasCodeModel": false,
    "activeBuildType": "",
    "buildTypesSeen": [],
    "requests": [],
    "responses": [],
    "partialMatches": [],
    "targetCount": 0,
    "executablesCount": 0,
    "librariesCount": 0,
    "targets": []
  },
  "settings": [
    {
      "communicationMode": "automatic",
      "useCMakePresets": "auto",
      "configureOnOpen": true
    }
  ]
}

Debug Log

[main] Configuring project: llvm-project 
[main] Saving open files before configure/build
[expand] expanded ${workspaceFolder}/build
[driver] Start configure 
[driver] Running pre-configure checks and steps
[driver] Using compilers in Clang 21.1.3 x86_64-pc-linux-gnu for configure
[expand] expanded ${workspaceFolder}/build
[cmakefileapi-driver] Configuring using kit
[cmakefileapi-driver] Invoking CMake /usr/bin/cmake with arguments ["-DCMAKE_BUILD_TYPE:STRING=Debug","-DLLVM_ENABLE_RUNTIMES:STRING=libc\\;compiler-rt","-DLLVM_LIBC_FULL_BUILD:BOOL=TRUE","-DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=TRUE","-DCMAKE_C_COMPILER:FILEPATH=/usr/bin/clang","-DCMAKE_CXX_COMPILER:FILEPATH=/usr/bin/clang++","-Wno-dev","--no-warn-unused-cli","-S","/workspaces/llvm-project/runtimes","-B","/workspaces/llvm-project/build","-G","Ninja"]
[proc] Executing command: /usr/bin/cmake -DCMAKE_BUILD_TYPE:STRING=Debug "-DLLVM_ENABLE_RUNTIMES:STRING=libc\;compiler-rt" -DLLVM_LIBC_FULL_BUILD:BOOL=TRUE -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=TRUE -DCMAKE_C_COMPILER:FILEPATH=/usr/bin/clang -DCMAKE_CXX_COMPILER:FILEPATH=/usr/bin/clang++ -Wno-dev --no-warn-unused-cli -S /workspaces/llvm-project/runtimes -B /workspaces/llvm-project/build -G Ninja
[proc]   with environment: {"GITHUB_TOKEN":"","GIT_COMMITTER_NAME":"GitHub","GITHUB_CODESPACE_TOKEN":"","USER":"vscode","FEATURE_SPARK_POST_COMMIT_CREATE_ITERATION":"true","HOSTNAME":"codespaces-1bbd91","SHLVL":"1","GITHUB_CODESPACES_PORT_FORWARDING_DOMAIN":"app.github.dev","HOME":"/home/vscode","OLDPWD":"/","LESS":"-R","CODESPACES":"true","ZSH":"/home/vscode/.oh-my-zsh","LSCOLORS":"Gxfxcxdxbxegedabagacad","PAGER":"less","GITHUB_GRAPHQL_URL":"https://api.github.com/graphql","GITHUB_USER":"kaladron","ContainerVersion":"13","LOGNAME":"vscode","GITHUB_API_URL":"https://api.github.com","RepositoryName":"llvm-project","_":"/usr/bin/cat","CLOUDENV_ENVIRONMENT_ID":"685acd55-6425-4176-bfe4-8f0aefff87b1","PATH":"/vscode/bin/linux-x64/385651c938df8a906869babee516bffd0ddb9829/bin/remote-cli:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/vcpkg:/home/vscode/.local/bin","SHELL_LOGGED_IN":"true","LS_COLORS":"","GITHUB_REPOSITORY":"kaladron/llvm-project","SHELL":"/bin/zsh","CXX":"clang++","VCPKG_ROOT":"/usr/local/vcpkg","GIT_COMMITTER_EMAIL":"noreply@github.com","INTERNAL_VSCS_TARGET_URL":"https://uksouth.online.visualstudio.com","PWD":"/vscode/bin/linux-x64/385651c938df8a906869babee516bffd0ddb9829","GITHUB_SERVER_URL":"https://github.com","CC":"clang","CODESPACE_NAME":"stunning-waddle-q6qvj4xp5h9j44","VCPKG_DOWNLOADS":"/usr/local/vcpkg-downloads","VSCODE_CWD":"/vscode/bin/linux-x64/385651c938df8a906869babee516bffd0ddb9829","VSCODE_NLS_CONFIG":"{\"userLocale\":\"en\",\"osLocale\":\"en\",\"resolvedLanguage\":\"en\",\"defaultMessagesFile\":\"/vscode/bin/linux-x64/385651c938df8a906869babee516bffd0ddb9829/out/nls.messages.json\",\"locale\":\"en\",\"availableLanguages\":{}}","VSCODE_HANDLES_SIGPIPE":"true","VSCODE_ESM_ENTRYPOINT":"vs/workbench/api/node/extensionHostProcess","VSCODE_HANDLES_UNCAUGHT_ERRORS":"true","BROWSER":"/vscode/bin/linux-x64/385651c938df8a906869babee516bffd0ddb9829/bin/helpers/browser.sh","ELECTRON_RUN_AS_NODE":"1","VSCODE_IPC_HOOK_CLI":"/tmp/vscode-ipc-55df85f6-72e8-43fb-b619-ec116feb96cc.sock","VSCODE_L10N_BUNDLE_LOCATION":""}
[cmake] Not searching for unused variables given on the command line.
[cmake] -- Performing standalone runtimes build.
[cmake] -- Could NOT find LLVM (missing: LLVM_DIR)
[cmake] -- Could NOT find Clang (missing: Clang_DIR)
[cmake] -- LLVM host triple: x86_64-unknown-linux-gnu
[cmake] -- LLVM default target triple: x86_64-unknown-linux-gnu
[cmake] -- check-runtimes does nothing.
[cmake] -- Configuring done (0.8s)
[cmake] -- Generating done (0.0s)
[cmake] -- Build files have been written to: /workspaces/llvm-project/build
[cmakefileapi-parser] Read reply folder: /workspaces/llvm-project/build/.cmake/api/v1/reply
[cmakefileapi-parser] Found index files: ["cache-v2-0ff43d3e98a0d8157e7e.json","cmakeFiles-v1-28606406d8aa38f024f9.json","codemodel-v2-8ba816393a0b81753bc6.json","directory-.-Debug-f5ebdc15457944623624.json","directory-llvm-lit-Debug-8fe87b22938f8f65fa0f.json","index-2025-10-08T07-08-07-0041.json","target-check-runtimes-Debug-a28468b45d8c5c9e6d1d.json","target-runtimes-test-depends-Debug-9e42429026bba7421282.json","toolchains-v1-783b4b70450f1473ff1d.json"]
[main] Cannot copy compile_commands.json because it does not exist at /workspaces/llvm-project/build/compile_commands.json
[ctest] Folder is not found in Test Explorer: /workspaces/llvm-project/runtimes
[extension] [7867] cmake.configure finished (returned 0)

Additional Information

No response

[yanghhhhhhh]

Hi @kaladron, thanks for reporting issue here!
We can reproduce this issue on VS Code 1.104.3 + CMake tools 1.21.36 version.
Repro Steps:

1. Download the attached project (llvm_test_project.zip) and open it.
2. Press F1, run command "CMake: Configure".
3. Observe the result.

Details please see following video:

FYI: @gcampbell-msft

[kaladron]

Hmm. So now I'm not sure of the correctness thing here. This extension is escaping the semicolons because the best way to specify these is with a list: ['foo', 'bar']. But I hadn't found any documentation on this. How I found out was that I asked copilot to generate an integration test for me, and it generated a test for BOTH the unescaped semicolon and the list that they did the right thing.

The correct fix to this bug may be a documentation patch. The docs currently say:

"NOTE: If you are setting an array argument within cmake.configureSettings, you should use array notation, i.e. "CONFIGURE_SETTINGS_LIST": [ "a", "b" ]"

And it would be helpful to clarify that semicolons will explicitly be escaped so that they are not interpreted as lists by CMake.

Also, would you like the additional tests? I'm happy to contribute them anyway since they got built. I just need to finish sorting out the CLA before I proceed with any code.

[yanghhhhhhh]

Thank you for the detailed information. Currently we can reproduce this issue. If we need any further additional tests, we will add a comment. Thank you for your support.