Buildling OpenJDK with Windows Subsystem for Linux

Thanks to Andrew Luo (and the JDK build team), it is now possible to build OpenJDK with Windows Subsystem for Linux on Windows 10 (1809+). This post will also use the JDK mirror at Github (if it is not synchronised, see the previous post for using Mercurial).

2019-01-19: added the Mercurial instructions

1. Activate Windows Subsystem for Linux
   In an administrative Powershell:
   

   Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Windows-Subsystem-Linux

   Restart then install, say, Ubuntu from the Windows Store
   Then launch wsl and complete the inialisation.
   See Microsoft documentation for the full instructions
2. Create a C:\dev\ directory 
3. Download and install Git (or/and Mercurial)
   
4. Download OpenJDK 11 and extract it to C:\dev\jdk-11.0.1
5. Download and install Visual Studio 2017 Build Tools (when installing select the Visual C++ Build Tools, and ensure the language module is English (only))
6. In a WSL console select the following packages
   

   sudo apt install autoconf
   sudo apt install make
   sudo apt install zip

    (unzip will be installed with zip)
7. Get OpenJDK's source:
   in a (cmd) console:
   

   cd C:\dev
   git clone https://github.com/openjdk/jdk.git

   or if it is not up to date:
   

   
   hg clone http://hg.openjdk.java.net/jdk/jdk/

   alternatively instead of attempting to clone from hg.openjdk.java.net (especially from Europe), download and extract Alexsey Shipilev's https://builds.shipilev.net/workspaces/jdk-jdk.tar.xz then extract in C:\dev\jdk then
   

   cd C:\dev
   hg pull
   hg update

   
   
8. Build OpenJDK
   in a (wsl) console:
   

   cd /mnt/c/dev/jdk
   bash configure --with-boot-jdk=/mnt/c/dev/jdk-11.0.1/ --disable-warnings-as-errors
   make images

   (--disable-warnings-as-errors so that VS2017 warnings are not stopping the build)
9. Test it
   in a (cmd) console:
   

   
   C:\dev\jdk\build\windows-x86_64-server-release\images\jdk\bin\java --version

10. hack!

See the JDK's building.md document for more information.