Add automatic color alias for diff (copied from grep)

DIFF_COLORS

@@ -0,0 +1,4 @@
+# Configuration file for the color diff utility
+
+# 'none' shuts colorization off.
+#COLOR none

colordiff.csh

@@ -0,0 +1,9 @@
+
+# color-diff initialization
+
+/usr/libexec/diffconf.sh -c
+if ( $status == 1 ) then
+    exit
+endif
+
+alias diff 'diff --color=auto'

colordiff.sh

@@ -0,0 +1,5 @@
+# color-diff initialization
+
+/usr/libexec/diffconf.sh -c || return
+
+alias diff='diff --color=auto' 2>/dev/null

diffconf.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+case "$1" in
+    -c | --interactive-color)
+        ! diff -qsi "^COLOR.*none" /etc/DIFF_COLORS
+        ;;
+    *)
+        echo >&2 "Invalid / no option passed, so far only -c | --interactive-color is supported."
+        exit 1
+        ;;
+esac

diffutils.spec

@@ -1,9 +1,13 @@
 Summary: GNU collection of diff utilities
 Name: diffutils
 Version: 3.12
-Release: 3%{?dist}
+Release: 4%{?dist}
 URL: https://www.gnu.org/software/diffutils/diffutils.html
 Source: https://ftp.gnu.org/gnu/diffutils/diffutils-%{version}.tar.xz
+Source2: colordiff.sh
+Source3: colordiff.csh
+Source4: DIFF_COLORS
+Source5: diffconf.sh
 # upstream fixes
 # cross compile build of 3.12 diffutils fails
 Patch: diffutils-3.12-cross-compiler-build-fail.patch
@@ -46,6 +50,11 @@ make PR_PROGRAM=%{_bindir}/pr
 %install
 %make_install
 
+mkdir -p $RPM_BUILD_ROOT%{_sysconfdir}/profile.d
+install -pm 644 %{SOURCE2} %{SOURCE3} $RPM_BUILD_ROOT%{_sysconfdir}/profile.d
+install -pm 644 %{SOURCE4} $RPM_BUILD_ROOT%{_sysconfdir}
+install -Dpm 755 %{SOURCE5} $RPM_BUILD_ROOT%{_libexecdir}/diffconf.sh
+
 rm -f $RPM_BUILD_ROOT%{_infodir}/dir
 %find_lang %{name}
 
@@ -60,8 +69,14 @@ make check
 %{_bindir}/*
 %{_mandir}/*/*
 %{_infodir}/diffutils.info*
+%config(noreplace) %{_sysconfdir}/profile.d/colordiff.*sh
+%config(noreplace) %{_sysconfdir}/DIFF_COLORS
+%{_libexecdir}/diffconf.sh
 
 %changelog
+* Sat Oct 25 2025 Fedora Release Engineering <releng@fedoraproject.org> - 3.12-4
+- add automatic color alias for diff (copied from grep)
+
 * Wed Jul 23 2025 Fedora Release Engineering <releng@fedoraproject.org> - 3.12-3
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_43_Mass_Rebuild