git-ffwd: use the push branch as the upstream, if no upstream configured

git-addons/git-ffwd

@@ -2,40 +2,100 @@
 SUBDIRECTORY_OK=1 source "$(git --exec-path)/git-sh-setup" ||
     die "Not a git repository."
 
+
+has_matching_push() {
+    # push.default is setup for 'simple', 'current', or 'matching'.
+    case "$(git config --get push.default || echo "matching")" in
+        current | simple | matching)
+            return 0
+    esac
+
+    return 1
+}
+
+
+if has_matching_push; then
+    MATCHING_PUSH=t
+else
+    MATCHING_PUSH=
+fi
+
+
+determine_upstream_branch() {
+    local ref="${1#refs/heads/}"
+    local upstream="$(git for-each-ref --format='%(upstream:short)' "refs/heads/$ref")"
+    local publish_branch
+
+    if [[ -n "$upstream" ]]; then
+        echo "$upstream"
+        return 0
+    fi
+
+    if [[ -z "$MATCHING_PUSH" ]]; then
+        return 1
+    fi
+
+    # Use the push location as the upstream.
+    local remote=$(git config --get branch.${ref}.pushremote ||
+        git config --get remote.pushdefault ||
+        git config --get branch.${ref}.remote)
+    if [ -z "$remote" -a -n "$(git config --get remote.origin.url 2> /dev/null)" ]; then
+        remote="origin"
+    fi
+    if [[ -n "$remote" ]]; then
+        git rev-parse "$remote/$ref" > /dev/null 2>&1 &&
+            publish_branch="$remote/$ref"
+    fi
+
+    if [[ -n "$publish_branch" ]]; then
+        echo "$publish_branch"
+        return 0
+    fi
+
+    return 1
+}
+
+
 # Taken from http://stackoverflow.com/questions/620650/can-i-easily-update-all-local-git-branches-from-remote-branches-simultaneously/answer-9076361
 # with a small tweak by me to make the fast-forward merge use --ff-only, and to
-# help prune remote branches.
+# help prune remote branches.  It has also been updated to treat the push branch
+# as the default upstream, if no upstream is configured.
 main() {
-  REMOTES="$@";
-  if [ -z "$REMOTES" ]; then
-    REMOTES=$(git remote);
-  fi
-  REMOTES=$(echo "$REMOTES" | xargs -n1 echo)
-  CLB=$(git branch -l|awk '/^\*/{print $2}');
-  echo "$REMOTES" | while read REMOTE; do
+    local upstream
+    local ALR
+    local LR
+
+    local CLB=$(git branch -l|awk '/^\*/{print $2}')
+
+    local REMOTES="$@"
+    if [ -z "$REMOTES" ]; then
+        REMOTES="$(git remote)"
+    fi
+    REMOTES="$(echo "$REMOTES" | xargs -n1 echo)"
+
     git remote update -p $REMOTE
-    git remote show $REMOTE -n \
-    | awk '/merges with remote/{print $5" "$1}' \
-    | while read line; do
-      RB=$(echo "$line"|cut -f1 -d" ");
-      ARB="refs/remotes/$REMOTE/$RB";
-      LB=$(echo "$line"|cut -f2 -d" ");
-      ALB="refs/heads/$LB";
-      NBEHIND=$(( $(git rev-list --count $ALB..$ARB 2>/dev/null) +0));
-      NAHEAD=$(( $(git rev-list --count $ARB..$ALB 2>/dev/null) +0));
-      if [ "$NBEHIND" -gt 0 ]; then
-        if [ "$NAHEAD" -gt 0 ]; then
-          echo " branch $LB is $NBEHIND commit(s) behind and $NAHEAD commit(s) ahead of $REMOTE/$RB. could not be fast-forwarded";
-        elif [ "$LB" = "$CLB" ]; then
-          echo " branch $LB was $NBEHIND commit(s) behind $REMOTE/$RB. fast-forward merge";
-          git merge --ff --ff-only -q $ARB;
-        else
-          echo " branch $LB was $NBEHIND commit(s) behind $REMOTE/$RB. resetting local branch to remote";
-          git branch -l -f $LB -t $ARB >/dev/null;
+    git show-ref --heads | cut -d ' ' -f 2 | while read ALB; do
+        LB="${ALB#refs/heads/}"
+        RB="$(determine_upstream_branch "${LB}")"
+        if [ -z "${RB}" ]; then
+            continue
+        fi
+
+        NBEHIND=$(( $(git rev-list --count $LB..$RB 2>/dev/null) +0))
+        NAHEAD=$(( $(git rev-list --count $RB..$LB 2>/dev/null) +0))
+
+        if [ "$NBEHIND" -gt 0 ]; then
+            if [ "$NAHEAD" -gt 0 ]; then
+                echo " branch $LB is $NBEHIND commit(s) behind and $NAHEAD commit(s) ahead of $RB. could not be fast-forwarded"
+            elif [ "$LB" = "$CLB" ]; then
+                echo " branch $LB was $NBEHIND commit(s) behind $RB. fast-forward merge";
+                git merge --ff --ff-only -q $RB
+            else
+                echo " branch $LB was $NBEHIND commit(s) behind $RB. resetting local branch to remote"
+                git branch -l -f $LB -t $RB >/dev/null
+            fi
         fi
-      fi
     done
-  done
 }
 
 main $@