Building GHC on Windows

Here is how you can build GHC, from source, on Windows. We assume that git and stack are installed (see prerequisites).

# Get GHC sources; git core.autocrlf should be set to false (see Prerequisites section)
git clone --recursive git://git.haskell.org/ghc.git
cd ghc

# Download and install the bootstrapping GHC and MSYS2
cd hadrian
stack setup

# Install utilities required during the GHC build process
stack exec -- pacman -S autoconf automake-wrapper make patch python tar --noconfirm

# Build Hadrian and dependencies (including GHC dependencies Alex and Happy)
stack build

# Build GHC
# Note that the --configure flag is required only for the first build
stack exec hadrian -- --directory ".." -j --flavour=quickest --configure

# Test GHC
cd ..
_build\stage1\bin\ghc -e 1+2

The entire process should take about 20 minutes. Note, this will build GHC without optimisations. If you need an optimised GHC, drop the --flavour=quickest flag from the build command line (this will slow down the build to about an hour).

These are currently not the official GHC building instructions, but are much simpler and may also be more robust.

The stack build and stack exec hadrian commands can be replaced by an invocation of Hadrian's Stack-based build script: build.stack.bat -j --flavour=quickest. Use this script if you plan to work on Hadrian and/or rebuild GHC often.

Prerequisites

The above works on a clean machine with git and stack installed (tested with default installation settings), which you can get from https://git-scm.com/download/win and https://www.stackage.org/stack/windows-x86_64-installer.

Note that git should be configured to check out Unix-style line endings. The default behaviour of git on Windows is to check out Windows-style line endings which can cause issues during the build. This can be changed using the following command:

git config --global core.autocrlf false

If you would like to restore the default behaviour later run:

git config --global core.autocrlf true

Testing

These instructions have been tested on a clean Windows 10 machine using the free VirtualBox image, and are also routinely tested on Hadrian's AppVeyor CI instance.

Notes

Beware of the current limitations of Hadrian.