mozjs_sys 0.61.10

System crate for the Mozilla SpiderMonkey JavaScript engine. failed to build mozjs_sys-0.61.10
Please check the build logs and, if you believe this is' fault, open an issue.

This repository contains Rust bindings for SpiderMonkey for use with Servo.

The bindings are to the raw SpiderMonkey API, higher-level bindings are in the rust-mozjs repository.


Under Linux:

Install Clang (at least version 3.9), for example in a Debian-based Linux:

sudo apt-get install clang-6.0

If you have more than one version of Clang installed, you can set the LIBCLANG_PATH environment variable, for example:

export LIBCLANG_PATH=/usr/lib/clang/4.0/lib

Under Windows:

  1. Follow the directions at

  2. Open up a shell configured to use Visual Studio. This could be the one included with Visual Studio (e.g. Visual Studio 2017 / X64 Native Tools Command Prompt for VS 2017) or a shell in which you have run

"c:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\VC\Auxiliary\Build\vcvars64.bat"
  1. Set the MOZTOOLS_PATH environment variable to point to the tools from the Mozilla Build Package:
set MOZTOOLS_PATH=C:\mozilla-build\msys\bin;C:\mozilla-build\bin
  1. Download and install Clang for Windows (64 bit) from and set the LIBCLANG_PATH environment variable to its lib directory:
set LIBCLANG_PATH=C:\Program Files\LLVM\lib
  1. Set environment variables so the build script can find Python 2.7 and Autoconf 2.13:
set AUTOCONF=C:\mozilla-build\msys\local\bin\autoconf-2.13
set NATIVE_WIN32_PYTHON=C:\mozilla-build\python\python2.7.exe

You can now build and test the crate using cargo:

cargo build
cargo test
cargo build --features debugmozjs
cargo test --features debugmozjs


In order to upgrade to a new version of SpiderMonkey:

  1. Find the mozilla-release commit for the desired version of SpiderMonkey, at You are looking for an SM(pkg) tagged with FIREFOX_RELEASE. Take a note of the commit number to the left (a hex number such as ac4fbb7aaca0).

  2. Click on the SM(pkg) link, which will open a panel with details of the commit, including an artefact uploaded link, with a name of the form mozjs-version.tar.bz2. Download it and save it locally.

  3. Look at the patches in etc/patches/*.patch, and remove any that no longer apply (with a bit of luck this will be all of them).

  4. Run python3 ./etc/ path/to/tarball.

  5. Update etc/COMMIT with the commit number.

  6. Build and test the bindings as above, then submit a PR!