Merge BlockstreamResearch/secp256k1-zkp#341: sync-upstream: Overhaul

656c7cc704 sync-upstream: Clarify that we merge a *single* upstream ref (Tim Ruffing)
349a94b169 sync-upstream: Remove "select" mode and simplify (Tim Ruffing)

Pull request description:

  Please see individual commit messages for details.

  ---

  Here's an example session that shows why `select` doesn't make sense:

  ```
  ### Let's find some PRs to sync (master is at 5a67b63)

  ❯ ./contrib/sync-upstream.sh -b master range
  Merging b9cb1cbf 1aafe151 . Continue with y
  n

  ### Let's look at them in the order they have been merged

  ❯ git show b9cb1cbf
  commit b9cb1cbfd7
  Merge: c0a2aba0 921b9711
  Author: merge-script <me@real-or-random.org>
  Date:   Tue Mar 3 15:31:46 2026 +0100

      Merge bitcoin-core/secp256k1#1824: util: introduce and use `ARRAY_SIZE` macro

  [...]

  ❯ git --no-pager show 1aafe151

  commit 1aafe15139 (upstream/master, upstream/HEAD)
  Merge: b9cb1cbf 4d92a083
  Author: merge-script <me@real-or-random.org>
  Date:   Wed Mar 4 08:43:07 2026 +0100

      Merge bitcoin-core/secp256k1#1777: Make SHA256 compression runtime pluggable

  [...]

  ### Let's assume I want to cherry-pick 1aafe151 but not sync b9cb1bcf

  ❯ ./contrib/sync-upstream.sh -b master select 1aafe151
  -----------------------------------
  Upstream PRs 1777
  -----------------------------------

  [bitcoin-core/secp256k1#1777]: Make SHA256 compression runtime pluggable

  This PR can be recreated with `./contrib/sync-upstream.sh -b master select 1aafe151`.

  [...]

  ### Let's check if it's really only PR #1777

  ❯ git diff | grep ARRAY_SIZE
  + #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))

  ### Ah damn, we also got the other PR #1824...
  ```

ACKs for top commit:
  mllwchrry:
    ACK 656c7cc
  jonasnick:
    ACK 656c7cc704

Tree-SHA512: 27cdfe7c6decce840ef4f2d12fa0a5fd829b35ac24403272c4b34c0a3b0da2303cee36bcb419d0608c6b1297fd5bf8a6cd6d41672850ac092814c140638f9d83

contrib/sync-upstream.sh

@@ -6,14 +6,11 @@ help() {
     echo "Sync merge commits from bitcoin-core/secp256k1 into secp256k1-zkp."
     echo
     echo "Usage:"
-    echo "  $0 [-b <branch>] range [end]"
+    echo "  $0 [-b <branch>] [end]"
     echo "      Merges every merge commit present in upstream/master and missing in <branch>"
     echo "      (default: master). If the optional [end] commit is provided, only merges"
     echo "      up to and including [end]."
     echo
-    echo "  $0 [-b <branch>] select <commit> ... <commit>"
-    echo "      Merges every selected merge commit into <branch> (default: master)."
-    echo
     echo "This tool creates a temporary branch and attempts to merge the upstream commits."
     echo "If there are merge conflicts, resolve them and run tests, then use the generated"
     echo "script contrib/gh-pr-create.sh to create the PR (requires the gh tool)."
@@ -25,8 +22,8 @@ help() {
     echo
     echo "Listing upstream merge commits:"
     echo "  To list merge commits in upstream/master that are missing from <branch> (oldest first):"
-    echo "    git log --oneline --merges \$(git merge-base upstream/master <branch>)..upstream/master | tac"
-    echo "  Use these for [end] in 'range' or as arguments to 'select'."
+    echo "    git log --oneline --topo-order --reverse --merges \$(git merge-base upstream/master <branch>)..upstream/master"
+    echo "  These are candidates for [end]."
     exit 1
 }
 
@@ -56,25 +53,21 @@ range() {
     if [ "$#" = 1 ]; then
         RANGEEND_COMMIT=$1
     fi
-
-    COMMITS=$(git --no-pager log --oneline --merges "$RANGESTART_COMMIT".."$RANGEEND_COMMIT")
-    COMMITS=$(echo "$COMMITS" | tac | awk '{ print $1 }' ORS=' ')
-    echo "Merging $COMMITS. Continue with y"
-    read -r yn
-    case $yn in
-        [Yy]* ) ;;
-        * ) exit 1;;
-    esac
+    COMMITS=$(git --no-pager log --pretty=format:%H --topo-order --reverse --merges "$RANGESTART_COMMIT".."$RANGEEND_COMMIT")
 }
 
-# Process -b <branch> argument
-while getopts "b:" opt; do
+# Process -b <branch> and -h arguments
+while getopts "b:h" opt; do
   case $opt in
     b)
       LOCAL_BRANCH=$OPTARG
       ;;
-    \?)
-      echo "Invalid option: -$OPTARG" >&2
+    h)
+      help
+      ;;
+    *)
+      echo
+      help
       ;;
   esac
 done
@@ -82,37 +75,18 @@ done
 # Shift off the processed options
 shift $((OPTIND -1))
 
-if [ "$#" -lt 1 ]; then
-    help
-fi
-
-case $1 in
-    range)
-        shift
-        setup
-        range "$@"
-        REPRODUCE_COMMAND="$0 -b $LOCAL_BRANCH range $RANGEEND_COMMIT"
-        ;;
-    select)
-        shift
-        setup
-        COMMITS=$*
-        REPRODUCE_COMMAND="$0 -b $LOCAL_BRANCH select $@"
-        ;;
-    help)
-        help
-        ;;
-    *)
-        help
-esac
+setup
+range "$@"
 
 TITLE="Upstream PRs"
+REPRODUCE_COMMAND="$0 -b $LOCAL_BRANCH $RANGEEND_COMMIT"
 BODY=""
 for COMMIT in $COMMITS
 do
     PRNUM=$(git log -1 "$COMMIT" --pretty=format:%s | sed s/'Merge \(bitcoin-core\/secp256k1\)\?#\([0-9]*\).*'/'\2'/)
     TITLE="$TITLE $PRNUM,"
     BODY=$(printf "%s\n%s" "$BODY" "$(git log -1 "$COMMIT" --pretty=format:%s | sed s/'Merge \(bitcoin-core\/secp256k1\)\?#\([0-9]*\)'/'[bitcoin-core\/secp256k1#\2]'/)")
+    LAST_COMMIT="$COMMIT"
 done
 # Remove trailing ","
 TITLE=${TITLE%?}
@@ -128,6 +102,13 @@ Tips:
 EOF
 )
 
+echo "Merging $TITLE. Continue with y"
+read -r yn
+case $yn in
+    [Yy]* ) ;;
+    * ) exit 1;;
+esac
+
 echo "-----------------------------------"
 echo "$TITLE"
 echo "-----------------------------------"
@@ -159,4 +140,4 @@ EOT
 chmod +x "$FNAME"
 echo Run "$FNAME" after solving the merge conflicts
 
-git merge --no-edit -m "Merge commits '$COMMITS' into temp-merge-$PRNUM" $COMMITS
+git merge --no-edit -m "Merge upstream '${LAST_COMMIT:0:7}' into temp-merge-$PRNUM" "$LAST_COMMIT"