llvm-sys 0.4.0

Bindings to LLVM's C API
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Rust bindings to LLVM's C API.


llvm-sys = "0.4.0"

You will need LLVM (>= 3.6) installed on your system to compile these bindings. The llvm-config tool must be on PATH so the build scripts can find it.

See the examples directory in this repository for API examples. There also exist some other projects using these bindings which may be informative1:

Most of the interfaces are not documented in these bindings. Refer to the LLVM documentation for more information, particularly the generated API documentation.

1 If you have your own project using these bindings that you think is worth mentioning here, by all means let me know.


When developing against LLVM, use of a build with debug assertions enabled is highly recommended. It is often unclear how ownership moves around the system when using many different features, and debug assertions can help detect errors before they cause hard-to-debug crashes.

API versioning

Note that currently there is no API versioning, so newer versions of LLVM may not work as expected. These should manifest as link-time errors in most cases, but LLVM's API stability guarantees are not very strong so using newer versions of the library may cause more esoteric bugs (none are known to exist, but be aware).


LLVM supports Windows and others have had success using llvm-sys on that platforms, but setting it up is not very easy. The binaries distributed on llvm.org are not suitable for building against LLVM as a library, so you'll probably need to compile it yourself. Ensure that the compiler you use for Rust and LLVM are the same (MSVC or MinGW).

Why not use librustc_llvm?

In many cases, the interfaces exposed by librustc_llvm are sufficient for code generation or whatever else you need to do with LLVM. When they are not, however, you must link to LLVM yourself, which if mixed with rustc's LLVM runs a significant risk of library version mismatches. Users should take care not to mix uses of the two crates for this reason.

Additionally, rustc_llvm is a private API for the Rust compiler and is subject to change without notice. This crate provides a stable API.