Merge branch 'en/rebase-consistency'

"git rebase" behaved slightly differently depending on which one of
the three backends gets used; this has been documented and an
effort to make them more uniform has begun.

* en/rebase-consistency:
  git-rebase: make --allow-empty-message the default
  t3401: add directory rename testcases for rebase and am
  git-rebase.txt: document behavioral differences between modes
  directory-rename-detection.txt: technical docs on abilities and limitations
  git-rebase.txt: address confusion between --no-ff vs --force-rebase
  git-rebase: error out when incompatible options passed
  t3422: new testcases for checking when incompatible options passed
  git-rebase.sh: update help messages a bit
  git-rebase.txt: document incompatible options

1 files changed, 39 insertions, 4 deletions

diff --git a/git-rebase.sh b/git-rebase.sh
index f3b10c7f62..7973447645 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -20,23 +20,23 @@ onto=!             rebase onto given branch instead of upstream
 r,rebase-merges?   try to rebase merges instead of skipping them
 p,preserve-merges! try to recreate merges instead of ignoring them
 s,strategy=!       use the given merge strategy
+X,strategy-option=! pass the argument through to the merge strategy
 no-ff!             cherry-pick all commits, even if unchanged
+f,force-rebase!    cherry-pick all commits, even if unchanged
 m,merge!           use merging strategies to rebase
 i,interactive!     let the user edit the list of commits to rebase
 x,exec=!           add exec lines after each commit of the editable list
 k,keep-empty	   preserve empty commits during rebase
 allow-empty-message allow rebasing commits with empty messages
-f,force-rebase!    force rebase even if branch is up to date
-X,strategy-option=! pass the argument through to the merge strategy
 stat!              display a diffstat of what changed upstream
 n,no-stat!         do not show diffstat of what changed upstream
 verify             allow pre-rebase hook to run
 rerere-autoupdate  allow rerere to update index with resolved conflicts
 root!              rebase all reachable commits up to the root(s)
 autosquash         move commits that begin with squash!/fixup! under -i
+signoff            add a Signed-off-by: line to each commit
 committer-date-is-author-date! passed to 'git am'
 ignore-date!       passed to 'git am'
-signoff            passed to 'git am'
 whitespace=!       passed to 'git apply'
 ignore-whitespace! passed to 'git apply'
 C=!                passed to 'git apply'
@@ -95,7 +95,7 @@ rebase_cousins=
 preserve_merges=
 autosquash=
 keep_empty=
-allow_empty_message=
+allow_empty_message=--allow-empty-message
 signoff=
 test "$(git config --bool rebase.autosquash)" = "true" && autosquash=t
 case "$(git config --bool commit.gpgsign)" in
@@ -521,6 +521,24 @@ then
 	git_format_patch_opt="$git_format_patch_opt --progress"
 fi
 
+if test -n "$git_am_opt"; then
+	incompatible_opts=$(echo " $git_am_opt " | \
+			    sed -e 's/ -q / /g' -e 's/^ \(.*\) $/\1/')
+	if test -n "$interactive_rebase"
+	then
+		if test -n "$incompatible_opts"
+		then
+			die "$(gettext "error: cannot combine interactive options (--interactive, --exec, --rebase-merges, --preserve-merges, --keep-empty, --root + --onto) with am options ($incompatible_opts)")"
+		fi
+	fi
+	if test -n "$do_merge"; then
+		if test -n "$incompatible_opts"
+		then
+			die "$(gettext "error: cannot combine merge options (--merge, --strategy, --strategy-option) with am options ($incompatible_opts)")"
+		fi
+	fi
+fi
+
 if test -n "$signoff"
 then
 	test -n "$preserve_merges" &&
@@ -529,6 +547,23 @@ then
 	force_rebase=t
 fi
 
+if test -n "$preserve_merges"
+then
+	# Note: incompatibility with --signoff handled in signoff block above
+	# Note: incompatibility with --interactive is just a strong warning;
+	#       git-rebase.txt caveats with "unless you know what you are doing"
+	test -n "$rebase_merges" &&
+		die "$(gettext "error: cannot combine '--preserve_merges' with '--rebase-merges'")"
+fi
+
+if test -n "$rebase_merges"
+then
+	test -n "$strategy_opts" &&
+		die "$(gettext "error: cannot combine '--rebase_merges' with '--strategy-option'")"
+	test -n "$strategy" &&
+		die "$(gettext "error: cannot combine '--rebase_merges' with '--strategy'")"
+fi
+
 if test -z "$rebase_root"
 then
 	case "$#" in