Add script to cherry pick patches to monorepo

Author: Mandeep Singh Grang

clang/automation/UNIX/cherry-pick-to-monorepo.sh

@@ -0,0 +1,53 @@
+#!/bin/bash
+
+# Note: Do the following before running this script:
+# 1. Checkout your old clang master branch (say <somedir>/llvm/tools/clang). Call this SRCDIR.
+# 2. Checkout the new monorepo (say <somedir>/src. Call this TGTDIR.
+# 3. cd $SRCDIR
+# 4. git log --pretty=oneline --format=%H > patchlist
+# 5. for i in `cat patchlist`; do git diff ${i}~1 ${i} > ${i}.patch; done
+
+SRCDIR=<>
+TGTDIR=<>
+PROJ=clang
+PATCHLIST=$SRCDIR/patchlist
+
+if [[ ! -f $PATCHLIST ]]; then
+  echo "error: $PATCHLIST not found."
+  exit 1
+fi
+
+SHA=`tail -n1 $PATCHLIST`
+if [[ ! -f "${SRCDIR}/${SHA}.patch" ]]; then
+  echo "error: ${SHA}.patch not found."
+  exit 1
+fi
+
+cd $SRCDIR
+COMMIT_TITLE="`git log -n 1 --pretty=oneline --format=%s $SHA`"
+COMMIT_MSG="`git log -n 1 --pretty=full $SHA`"
+
+cd $TGTDIR
+echo "Applying patch $SHA ..."
+
+patch -p1 --directory=$TGTDIR/$PROJ < $SRCDIR/${SHA}.patch
+if [[ $? -ne 0 ]]; then
+  echo "error: Patch $SHA failed to apply cleanly."
+  exit 1
+fi
+
+git add $PROJ && git commit -m "${COMMIT_TITLE}
+
+Cherry-picked from ${COMMIT_MSG}"
+
+if [[ $? -ne 0 ]]; then
+  echo "error: Cherry-pick failed."
+  exit 1
+fi
+
+echo "Successfully applied patch $SHA"
+
+sed -i '$ d' $PATCHLIST
+rm -rf ${SRCDIR}/${SHA}.patch
+
+echo "Patches remaining: `wc -l $PATCHLIST | cut -f1 -d' '`"