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Add some additional information about running clangd for LSP when clang is not your normal compiler. Signed-off-by: Jonathon Jongsma <jjongsma@redhat.com> Reviewed-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-By: Tim Small <tim@seoss.co.uk>
69 lines
2.4 KiB
ReStructuredText
69 lines
2.4 KiB
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=========================
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Using Clangd with Libvirt
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=========================
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`clangd <https://clangd.llvm.org/>`__ is an implementation of the
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`language server protocol
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<https://en.wikipedia.org/wiki/Language_Server_Protocol>`__ for C
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and C++.
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When paired with an LSP-compatible editor or IDE (e.g. emacs,
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vim, vscode), ``clangd`` can helpful when working with libvirt's
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C sources e.g. navigating the code base.
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Whilst other C LSPs are available, ``clangd`` should work
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correctly with the libvirt because clang is a supported compiler
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for libvirt, and ``clangd`` is part of the same code base as
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clang.
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If clang is the default compiler on your system, then ``clangd``
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can be used as soon as ``meson setup`` has been run.
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If gcc is your build environment's default compiler, then
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additional steps are required to use ``clangd``:
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``clangd`` looks for a ``compile_commands.json`` file in the top
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level directory of the project and also in the ``build/``
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subdirectory to discover which include paths, compiler flags etc.
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should be used when it parses each source file.
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Meson creates a ``compile_commands.json`` in the build directory.
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Meson defaults to the system's default C compiler. When the
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default compiler is gcc, its ``compile_commands.json`` output
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cannot be used with ``clangd`` due to differences in compiler
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invocation flags when building libvirt.
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Create a separate build directory with a ``clangd`` compatible
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``compile_commands.json`` as follows:
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::
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CC=clang CXX=clang++ meson setup build-clang
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There are a small number of source files that are generated as part of the
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build process. In order to navigate this generated source code, you should also
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execute a build in this directory:
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::
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ninja -C build-clang
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Point ``clangd`` (v12 or later) at the correct
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``compile_commands.json`` by placing the following into a
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``.clangd`` file in the root of the project:
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::
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---
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CompileFlags:
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CompilationDatabase: "build-clang"
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Please note that if you are not using clang for your daily development, the
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``build-clang`` directory can get out of sync with the current state of the
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project over time. When you update your git checkout, new files may be added or
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configuration options changed and ``clangd`` may start to behave unpredictably.
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In this case, you will need to update your compilation database by doing a new
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build in the ``build-clang`` directory. This should allow clangd to work
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reliably again.
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