true built-in diff: run everything in-core.

diff --git a/git-diff.sh b/git-diff.sh
index b3ec84be698311b30e8c7c793873e6caa41daf71..dc0dd312bfb83921e1c52849a23ece84a05b5ecd 100755 (executable)
--- a/git-diff.sh
+++ b/git-diff.sh
@@ -3,12 +3,14 @@
 # Copyright (c) 2005 Linus Torvalds
 # Copyright (c) 2005 Junio C Hamano
 
+USAGE='[ --diff-options ] <ent>{0,2} [<path>...]'
+SUBDIRECTORY_OK='Yes'
+. git-sh-setup
+
 rev=$(git-rev-parse --revs-only --no-flags --sq "$@") || exit
 flags=$(git-rev-parse --no-revs --flags --sq "$@")
 files=$(git-rev-parse --no-revs --no-flags --sq "$@")
 
-: ${flags:="'-M' '-p'"}
-
 # I often say 'git diff --cached -p' and get scolded by git-diff-files, but
 # obviously I mean 'git diff --cached -p HEAD' in that case.
 case "$rev" in
@@ -20,10 +22,33 @@ case "$rev" in
        esac
 esac
 
+# If we have -[123] --ours --theirs --base, don't do --cc by default.
+case " $flags " in
+*" '-"[123]"' "* | *" '--ours' "* | *" '--base' "* | *" '--theirs' "*)
+       cc_or_p=-p ;;
+*)
+       cc_or_p=--cc ;;
+esac
+
+# If we do not have --name-status, --name-only, -r, or -c default to --cc.
+case " $flags " in
+*" '--name-status' "* | *" '--name-only' "* | *" '-r' "* | *" '-c' "* )
+       ;;
+*)
+       flags="$flags'$cc_or_p' " ;;
+esac
+
+# If we do not have -B, -C, -r, nor -p, default to -M.
+case " $flags " in
+*" '-"[BCMrp]* | *" '--find-copies-harder' "*)
+       ;; # something like -M50.
+*)
+       flags="$flags'-M' " ;;
+esac
+
 case "$rev" in
 ?*' '?*' '?*)
-       echo >&2 "I don't understand"
-       exit 1
+       usage
        ;;
 ?*' '^?*)
        begin=$(expr "$rev" : '.*^.\([0-9a-f]*\).*') &&
@@ -40,7 +65,7 @@ case "$rev" in
        cmd="git-diff-files $flags -- $files"
        ;;
 *)
-       die "I don't understand $*"
+       usage
        ;;
 esac