reactormonk / ghc.nix

Nix (shell) expression for working on GHC

Simple usage

Quickstart

To enter an environment without cloning this repository you can run:

nix-shell https://github.com/alpmestan/ghc.nix/archive/master.tar.gz

Building GHC

These commands assume you have cloned this repository to ~/ghc.nix. default.nix has many parameters, all of them optional. You should take a look at default.nix for more details.

$ echo "BuildFlavour = quick" > mk/build.mk
$ cat mk/build.mk.sample >> mk/build.mk
$ nix-shell ~/ghc.nix/ --run './boot && ./configure $CONFIGURE_ARGS && make -j4'
# works with --pure too

Note that we passed $CONFIGURE_ARGS to ./configure. While this is technically optional, this argument ensures that configure knows where the compiler's dependencies (e.g. gmp, libnuma, libdw) are found, allowing the compiler to be used even outsite of nix-shell. For convenience, the nix-shell environment also exports a convenience command, configure_ghc, which invokes configure as indicated.

You can alternatively use Hadrian to build GHC:

$ nix-shell ~/ghc.nix/
# from the nix shell:
$ ./boot && ./configure $CONFIGURE_ARGS
# example hadrian command: use 4 cores, build a 'quickest' flavoured GHC
# and place all the build artifacts under ./_mybuild/.
$ hadrian/build -j4 --flavour=quickest --build-root=_mybuild
# you could also ask hadrian to boot and configure for you, with -c

# if you have never used cabal-install on your machine, you will likely
# need to run the following before the hadrian command:
$ cabal update

Using ghcide (⚠️ currently unavailable)

You can also use `ghc.nix` to provide the right version of `ghcide` if you want to use `ghcide` whilst developing on GHC. In order to do so, pass the `withIde` argument to your `nix-shell` invocation.

nix-shell ~/.ghc.nix --arg withIde true

GHCIDE support is currently unavailable for GHC > 8.8.

See:

• cachix/ghcide-nix#3
• alpmestan#64

Running ./validate

$ nix-shell ~/ghc.nix/ --pure --run 'THREADS=4 ./validate'

See other flags of validate by invoking ./validate --help or just by reading its source code. Note that ./validate --slow builds the compiler in debug mode which has the side-effect of disabling performance tests.

Building and running for i686-linux from x86_64-linux

It's trivial!

$ nix-shell ~/ghc.nix/ --arg nixpkgs '(import <nixpkgs> {}).pkgsi686Linux'

TODO

• We currently can't just invoke nix-build (#1)
• We do not support all the cross compilation machinery that head.nix from nixpkgs supports.
• Some tests actually break with GHCs built with the first command above.