# clang-sys [](https://crates.io/crates/clang-sys) [](https://docs.rs/clang-sys) [](https://github.com/KyleMayes/vulkanalia/actions?query=workflow%3ACI)  Rust bindings for `libclang`. If you are interested in a somewhat idiomatic Rust wrapper for these bindings, see [`clang-rs`](https://github.com/KyleMayes/clang-rs). Released under the Apache License 2.0. ## [Documentation](https://docs.rs/clang-sys) Note that the documentation on https://docs.rs for this crate assumes usage of the `runtime` Cargo feature as well as the Cargo feature for the latest supported version of `libclang` (e.g., `clang_13_0`), neither of which are enabled by default. Due to the usage of the `runtime` Cargo feature, this documentation will contain some additional types and functions to manage a dynamically loaded `libclang` instance at runtime. Due to the usage of the Cargo feature for the latest supported version of `libclang`, this documentation will contain constants and functions that are not available in the oldest supported version of `libclang` (3.5). All of these types and functions have a documentation comment which specifies the minimum `libclang` version required to use the item. ## Supported Versions To target a version of `libclang`, enable a Cargo features such as one of the following: * `clang_3_5` - requires `libclang` 3.5 or later * `clang_3_6` - requires `libclang` 3.6 or later * etc... * `clang_12_0` - requires `libclang` 12.0 or later * `clang_13_0` - requires `libclang` 13.0 or later If you do not enable one of these features, the API provided by `libclang` 3.5 will be available by default. ## Dependencies By default, this crate will attempt to link to `libclang` dynamically. In this case, this crate depends on the `libclang` shared library (`libclang.so` on Linux, `libclang.dylib` on macOS, `libclang.dll` on Windows). If you want to link to `libclang` statically instead, enable the `static` Cargo feature. In this case, this crate depends on the LLVM and Clang static libraries. If you don't want to link to `libclang` at compiletime but instead want to load it at runtime, enable the `runtime` Cargo feature. These libraries can be either be installed as a part of Clang or downloaded [here](http://llvm.org/releases/download.html). **Note:** The downloads for LLVM and Clang 3.8 and later do not include the `libclang.a` static library. This means you cannot link to any of these versions of `libclang` statically unless you build it from source. ### Versioned Dependencies This crate supports finding versioned instances of `libclang.so` (e.g.,`libclang-3.9.so`). In the case where there are multiple instances to choose from, this crate will prefer instances with higher versions. For example, the following instances of `libclang.so` are listed in descending order of preference: 1. `libclang-4.0.so` 2. `libclang-4.so` 3. `libclang-3.9.so` 4. `libclang-3.so` 5. `libclang.so` **Note:** On BSD distributions, versioned instances of `libclang.so` matching the pattern `libclang.so.*` (e.g., `libclang.so.7.0`) are also included. **Note:** On Linux distributions when the `runtime` features is enabled, versioned instances of `libclang.so` matching the pattern `libclang.so.*` (e.g., `libclang.so.1`) are also included. ## Environment Variables The following environment variables, if set, are used by this crate to find the required libraries and executables: * `LLVM_CONFIG_PATH` **(compiletime)** - provides a full path to an `llvm-config` executable (including the executable itself [i.e., `/usr/local/bin/llvm-config-8.0`]) * `LIBCLANG_PATH` **(compiletime)** - provides a path to a directory containing a `libclang` shared library or a full path to a specific `libclang` shared library * `LIBCLANG_STATIC_PATH` **(compiletime)** - provides a path to a directory containing LLVM and Clang static libraries * `CLANG_PATH` **(runtime)** - provides a path to a `clang` executable ## Linking ### Dynamic `libclang` shared libraries will be searched for in the following directories: * the directory provided by the `LIBCLANG_PATH` environment variable * the `bin` and `lib` directories in the directory provided by `llvm-config --libdir` * the directories provided by `LD_LIBRARY_PATH` environment variable * a list of likely directories for the target platform (e.g., `/usr/local/lib` on Linux) * **macOS only:** the toolchain directory in the directory provided by `xcode-select --print-path` On Linux, running an executable that has been dynamically linked to `libclang` may require you to add a path to `libclang.so` to the `LD_LIBRARY_PATH` environment variable. The same is true on OS X, except the `DYLD_LIBRARY_PATH` environment variable is used instead. On Windows, running an executable that has been dynamically linked to `libclang` requires that `libclang.dll` can be found by the executable at runtime. See [here](https://msdn.microsoft.com/en-us/library/7d83bc18.aspx) for more information. ### Static The availability of `llvm-config` is not optional for static linking. Ensure that an instance of this executable can be found on your system's path or set the `LLVM_CONFIG_PATH` environment variable. The required LLVM and Clang static libraries will be searched for in the same way as shared libraries are searched for, except the `LIBCLANG_STATIC_PATH` environment variable is used in place of the `LIBCLANG_PATH` environment variable. ### Runtime The `clang_sys::load` function is used to load a `libclang` shared library for use in the thread in which it is called. The `clang_sys::unload` function will unload the `libclang` shared library. `clang_sys::load` searches for a `libclang` shared library in the same way one is searched for when linking to `libclang` dynamically at compiletime.