Subtree update automation: use fast version of subtree split

.github/workflows/update-subtree.yml

@@ -11,7 +11,10 @@ defaults:
 
 jobs:
  update-subtree-library:
- runs-on: ubuntu-latest
+ # Changing the host platform may alter the libgit2 version as used by
+ # splitsh-lite, which will require changing the version of git2go.
+ # See https://github.com/jeffWelling/git2go?tab=readme-ov-file#which-go-version-to-use
+ runs-on: ubuntu-24.04
 
  steps:
  - name: Checkout Repository
@@ -34,12 +37,6 @@ jobs:
  fetch-depth: 0
  path: rust-tmp
 
- - name: Checkout git-filter-repo
- uses: actions/checkout@v4
- with:
- repository: newren/git-filter-repo
- path: git-filter-repo
-
  - name: Fetch toolchain versions
  run: |
  CURRENT_TOOLCHAIN_DATE=$(grep -oP 'channel = "nightly-\K\d{4}-\d{2}-\d{2}' verify-rust-std/rust-toolchain.toml)
@@ -77,6 +74,30 @@ jobs:
  env:
  GH_TOKEN: ${{ github.token }}
 
+ - name: Checkout splitsh-lite
+ if: ${{ env.SUBTREE_PR_EXISTS == 'no' }}
+ uses: actions/checkout@v4
+ with:
+ repository: splitsh/lite
+ path: splitsh-lite
+
+ - name: Build splitsh-lite
+ if: ${{ env.SUBTREE_PR_EXISTS == 'no' }}
+ run: |
+ cd splitsh-lite
+ sudo apt-get install -y golang libgit2-dev
+ # git2go upstream hasn't been updated to more recent versions of
+ # libgit2, so using a fork that does stay up to date
+ sed -i 's#github.com/libgit2/git2go#github.com/jeffwelling/git2go#' go.mod splitter/*
+ # may need to adjust "v37" to a higher number per
+ # https://github.com/jeffWelling/git2go?tab=readme-ov-file#which-go-version-to-use
+ # depening on the libgit2 version being installed
+ sed -i -e 's/v34/v37/g' go.mod splitter/*.go
+ # v37.0.0 had issues that weren't fully fixed until v37.0.4
+ sed -i 's/v37.0.0/v37.0.4/' go.mod
+ go mod tidy
+ go build -o splitsh-lite github.com/splitsh/lite
+
  - name: Update subtree/library locally
  if: ${{ env.SUBTREE_PR_EXISTS == 'no' }}
  run: |
@@ -89,16 +110,13 @@ jobs:
  fi
 
  git checkout ${NEXT_COMMIT_HASH}
- ../git-filter-repo/git-filter-repo --subdirectory-filter library --force
- git checkout -b subtree/library
+/usr/bin/time -v ../splitsh-lite/splitsh-lite --progress --prefix=library --target subtree/library
+ git checkout -b subtree/library subtree/library
 
  cd ../verify-rust-std
  git remote add rust-filtered ../rust-tmp/
  git fetch rust-filtered
  git checkout -b subtree/library rust-filtered/subtree/library
- # The filter-subtree operation adds an extraneous `library/` folder containing the submodules
- # (c.f. https://github.com/model-checking/verify-rust-std/issues/249), so remove that before committing.
- rm -rf library
  SUBTREE_HEAD_MSG=$(git log --format=%s -n 1 origin/subtree/library)
  UPSTREAM_FROM=$(git log --grep="${SUBTREE_HEAD_MSG}" -n 1 --format=%H rust-filtered/subtree/library)
  UPSTREAM_HEAD=$(git log --format=%H -n 1 rust-filtered/subtree/library)
@@ -107,7 +125,6 @@ jobs:
  echo "MERGE_CONFLICTS=noop" >> $GITHUB_ENV
  else
  git branch --set-upstream-to=origin/subtree/library
- git -c user.name=gitbot -c user.email=git@bot rebase
  echo "MERGE_CONFLICTS=maybe" >> $GITHUB_ENV
  fi
 
@@ -130,12 +147,15 @@ jobs:
  if: ${{ env.MERGE_CONFLICTS != 'noop' && env.MERGE_PR_EXISTS == 'no' }}
  run: |
  cd verify-rust-std
+ if ! git rev-parse --verify subtree/library; then
+ git checkout -t -b subtree/library origin/update-subtree/library
+ fi
  git checkout main
 
  # This command may fail, which will require human intervention.
  if ! git \
  -c user.name=gitbot -c user.email=git@bot \
- subtree merge --prefix=library update-subtree/library --squash; then
+ subtree merge --prefix=library subtree/library --squash; then
  echo "MERGE_CONFLICTS=yes" >> $GITHUB_ENV
  git -c user.name=gitbot -c user.email=git@bot commit -a -m "Merge from $NEXT_COMMIT_HASH with conflicts"
  else