mozjs_sys 0.67.1

System crate for the Mozilla SpiderMonkey JavaScript engine. failed to build mozjs_sys-0.67.1
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Visit the last successful build: mozjs_sys-0.51.4

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) and autoconf v 2.13, for example in a Debian-based Linux:

sudo apt-get install clang-6.0 autoconf2.13

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!