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[Clang] [Docs] Add some CMake example code for linking against libclang #166268

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Sirraide merged 3 commits into from
Nov 4, 2025
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[Clang] [Docs] Add some CMake example code for linking against libclang #166268

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[Clang] [Docs] Add some CMake example code for linking against libclang
Sirraide Nov 3, 2025
fc669e0
Set CMake version requirement to 3.20 to match our CMakeLists.txt
Sirraide Nov 3, 2025
d27525b
Add some information on how to use a custom build of clang
Sirraide Nov 3, 2025
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33 changes: 33 additions & 0 deletions clang/docs/LibClang.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@ Code example

.. code-block:: cpp

// main.cpp
#include <clang-c/Index.h>
#include <iostream>

Expand All @@ -57,6 +58,22 @@ Code example
CXCursor cursor = clang_getTranslationUnitCursor(unit); //Obtain a cursor at the root of the translation unit
}

.. code-block:: cmake

# CMakeLists.txt
cmake_minimum_required(VERSION 3.20)
project(my_clang_tool VERSION 0.1.0)

# This will find the default system installation of Clang; if you want to
# use a different build of clang, pass -DClang_DIR=/foobar/lib/cmake/clang
# to the CMake configure command, where /foobar is the build directory where
# you built Clang.
find_package(Clang CONFIG REQUIRED)

add_executable(my_clang_tool main.cpp)
target_include_directories(my_clang_tool PRIVATE ${CLANG_INCLUDE_DIRS})
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@Endilll Endilll Nov 4, 2025 •
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This whole target_include_directories invocation should not have been needed if we had our CMake code in shape, but that's not your fault anyway.

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@Sirraide Sirraide Nov 4, 2025

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Yeah, normally target_link_libraries should set the include directories properly, but I distinctly recall running into horrible crashes on several occasions whenever I forgot this step because it’d find my system clang headers but link against my more up-to-date local clang build, which of course didn’t end well, so I made sure to include that here.

target_link_libraries(my_clang_tool PRIVATE libclang)

Visiting elements of an AST
~~~~~~~~~~~~~~~~~~~~~~~~~~~
The elements of an AST can be recursively visited with pre-order traversal with ``clang_visitChildren``.
Expand Down Expand Up @@ -283,6 +300,7 @@ Complete example code

.. code-block:: cpp

// main.cpp
#include <clang-c/Index.h>
#include <iostream>

Expand Down Expand Up @@ -356,6 +374,21 @@ Complete example code
);
}

.. code-block:: cmake

# CMakeLists.txt
cmake_minimum_required(VERSION 3.20)
project(my_clang_tool VERSION 0.1.0)

# This will find the default system installation of Clang; if you want to
# use a different build of clang, pass -DClang_DIR=/foobar/lib/cmake/clang
# to the CMake configure command, where /foobar is the build directory where
# you built Clang.
find_package(Clang CONFIG REQUIRED)

add_executable(my_clang_tool main.cpp)
target_include_directories(my_clang_tool PRIVATE ${CLANG_INCLUDE_DIRS})
target_link_libraries(my_clang_tool PRIVATE libclang)

.. _Index.h: https://github.com/llvm/llvm-project/blob/main/clang/include/clang-c/Index.h

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