Clangd LSP set incorrect root and missing arguments #11617

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1. wangzw

   added

   bugSomething isn't workingSomething isn't working

   on Feb 1, 2026
2. github-actions

   assigned

   rekram1-node

   on Feb 1, 2026
3. github-actions commented on Feb 1, 2026

   

   github-actionsBot

   on Feb 1, 2026 – with GitHub Actions

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   This issue might be a duplicate of existing issues. Please check:

   • clangd LSP always fails #9521: clangd LSP always fails - reports bogus STL include errors when projects provide compile_commands.json via symlink
   • [FEATURE]: LSP support for choosing between multiple build directories (c++ / clangd) #7780: [FEATURE]: LSP support for choosing between multiple build directories (c++ / clangd) - discusses the need to configure build directory for clangd, similar to passing compile_commands.json location

   Feel free to ignore if none of these address your specific case.
4. BLumia commented on Apr 2, 2026

   

   BLumia

   on Apr 2, 2026

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   Not sure if you are using Windows, if so, you might need to ensure opencode is using the clangd that you expect it to use. For me OpenCode by default will attempt to download and use its own clangd but I need to make it use MSYS2's clangd, thus custom configuration needed. See #7405 (comment) for example configuration.
5. wangzw commented on Apr 7, 2026

   

   wangzw

   on Apr 7, 2026

   Last edited by wangzw

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   Not sure if you are using Windows, if so, you might need to ensure opencode is using the clangd that you expect it to use. For me OpenCode by default will attempt to download and use its own clangd but I need to make it use MSYS2's clangd, thus custom configuration needed. See #7405 (comment) for example configuration.

   I'm working MacOS and Linux. I have already submitted a patch (#11579), but the PR was ignored. So I gave up.

   😕React with 😕1Reacted by Jack Manning

   ❤️React with ❤️1Reacted by Gary Wang
6. wangzw

   closed this as completedon Apr 7, 2026
7. nonbanana commented on Apr 8, 2026

   

   nonbanana

   on Apr 8, 2026

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   I agree with this issue. In most Make and CMake projects, Makefile and CMakeLists.txt do not indicate the project root — they exist in countless subdirectories throughout the tree.

   llvm-project (https://github.com/llvm/llvm-project) is good example. llvm-project has CMakeLists.txt in every single subdirectory like clang/lib/Sema/, clang/lib/AST/, clang/lib/CodeGen/, etc. Opening any file there causes clangd to start in the wrong directory.
   These markers should be removed from the clangd root detection. Only compile_commands.json, compile_flags.txt, and .clangd reliably indicate where clangd should run.

   👍React with 👍1Reacted by FrankHB
8. AadityaRavindran commented on Apr 23, 2026

   

   AadityaRavindran

   on Apr 23, 2026

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   For ROS c++ projects, the build directory is not in the src directory. The folder structure is

   ros_ws/
    |- build/compile_commands.json
    |- src/package/CMakeLists.txt
   

   If I'm not mistaken, NearestRoot is excluding parent folders, so even if the compile_commands.json file was in ros_ws/compile_commands.json, it wouldn't find it. It would be nice if we could configure the build directory explicitly. It would also be helpful to add a note to https://opencode.ai/docs/lsp#how-it-works which talks about the location of compile commands, or how to configure the build directory for clangd.

   I believe this is how we do it now, but making this explicit in the documentation would help.

   {
     "$schema": "https://opencode.ai/config.json",
     "permission": {
       "lsp": "allow"
     },
     "lsp": {
       "clangd": {
         "command": [
           "clangd",
           "--compile-commands-dir=<your build directory with the compile_commands.json file>"
         ]
       }
     }
   }