Ports: Port gn

This requires allowing ports to override fetch() since tar.gz sha256sums
from googlesource.com are not deterministic.

Ports/.port_include.sh

@@ -310,7 +310,8 @@ do_download_file() {
  fi
 }
 
-fetch() {
+# FIXME: Don't allow overriding fetch, support multiple protocols instead. See #20004
+func_defined fetch || fetch() {
  pre_fetch
 
  tried_download_again=0

Ports/AvailablePorts.md

@@ -94,6 +94,7 @@ This list is also available at [ports.serenityos.net](https://ports.serenityos.n
 | [`gltron`](gltron/) | GLTron | 0.70 | http:https://gltron.org |
 | [`glu`](glu/) | Mesa GLU | 9.0.2 | https://gitlab.freedesktop.org/mesa/glu |
 | [`gmp`](gmp/) | GNU Multiple Precision Arithmetic Library (GMP) | 6.2.1 | https://gmplib.org/ |
+| [`gn`](gn/) | GN Meta Build System | 2023.07.12 | https://gn.googlesource.com/gn/ |
 | [`gnuapl`](gnuapl/) | GNU APL | 1.8 | https://www.gnu.org/software/apl/ |
 | [`gnucobol`](gnucobol/) | GnuCOBOL | 3.1.2 | https://gnucobol.sourceforge.io/ |
 | [`gnupg`](gnupg/) | GnuPG | 2.3.0 | https://gnupg.org/software/index.html |

Ports/gn/package.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env -S bash ../.port_include.sh
+port='gn'
+workdir='gn'
+version='2023.07.12'
+repository='https://gn.googlesource.com/gn'
+git_rev='fae280eabe5d31accc53100137459ece19a7a295'
+useconfigure='true'
+# FIXME: The files and auth_type are lies here. See #20004
+files=('git')
+auth_type='sha256'
+depends=(
+ 'ninja'
+ 'python3'
+)
+
+fetch() {
+ if [ ! -d ${workdir} ]; then
+ git clone ${repository} ${workdir}
+ fi
+ run git checkout ${git_rev}
+}
+
+configure() {
+ run python3 build/gen.py --platform='serenity' --allow-warnings
+}
+
+build() {
+ run ninja -C out
+}
+
+install() {
+ run mkdir -p "${SERENITY_INSTALL_ROOT}/usr/local/bin"
+ run cp out/gn "${SERENITY_INSTALL_ROOT}/usr/local/bin"
+ run cp out/gn_unittests "${SERENITY_INSTALL_ROOT}/usr/local/bin"
+}