gecko-dev/third_party/rust/clang-sys/README.md

clang-sys

Rust bindings for libclang.

If you are interested in a Rust wrapper for these bindings, see clang-rs.

Supported on the stable, beta, and nightly Rust channels.

Released under the Apache License 2.0.

Supported Versions

To target a version of libclang, enable one of the following Cargo features:

• clang_3_5 - requires libclang 3.5 or later (Documentation)
• clang_3_6 - requires libclang 3.6 or later (Documentation)
• clang_3_7 - requires libclang 3.7 or later (Documentation)
• clang_3_8 - requires libclang 3.8 or later (Documentation)
• clang_3_9 - requires libclang 3.9 or later (Documentation)
• clang_4_0 - requires libclang 4.0 or later (Documentation)
• clang_5_0 - requires libclang 5.0 or later (Documentation)
• clang_6_0 - requires libclang 6.0 or later (Documentation)
• clang_7_0 - requires libclang 7.0 or later (Documentation)
• clang_8_0 - requires libclang 8.0 or later (Documentation)

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 OS X, 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.

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 path to an llvm-config executable
• LIBCLANG_PATH (compiletime) - provides a path to a directory containing a 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 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.