From 367fcd9eb590d002cbbae23f22b1395b7d3303e6 Mon Sep 17 00:00:00 2001
From: Matthew Kenigsberg <matthewkenigsberg@gmail.com>
Date: Thu, 2 Mar 2023 17:29:36 -0700
Subject: [PATCH] installer: don't assume GNU diff

macOS Ventura ships with it's own version of diff. Try to output a
similar diff with Apple diff as with GNU diff, instead of failing

Helps https://github.com/NixOS/nix/issues/7286
---
 scripts/install-multi-user.sh | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/scripts/install-multi-user.sh b/scripts/install-multi-user.sh
index 7c66538b0..79deb2819 100644
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -246,8 +246,15 @@ printf -v _OLD_LINE_FMT "%b" $'\033[1;7;31m-'"$ESC ${RED}%L${ESC}"
 printf -v _NEW_LINE_FMT "%b" $'\033[1;7;32m+'"$ESC ${GREEN}%L${ESC}"
 
 _diff() {
+    # macOS Ventura doesn't ship with GNU diff. Print similar output except
+    # without +/- markers or dimming
+    if diff --version | grep -q "Apple diff"; then
+        printf -v CHANGED_GROUP_FORMAT "%b" "${GREEN}%>${RED}%<${ESC}"
+        diff --changed-group-format="$CHANGED_GROUP_FORMAT" "$@"
+    else
     # simple colorized diff comatible w/ pre `--color` versions
-    diff --unchanged-group-format="$_UNCHANGED_GRP_FMT" --old-line-format="$_OLD_LINE_FMT" --new-line-format="$_NEW_LINE_FMT" --unchanged-line-format="  %L" "$@"
+        diff --unchanged-group-format="$_UNCHANGED_GRP_FMT" --old-line-format="$_OLD_LINE_FMT" --new-line-format="$_NEW_LINE_FMT" --unchanged-line-format="  %L" "$@"
+    fi
 }
 
 confirm_rm() {