Use git-filter-repo

Author: tautschnig

.github/workflows/update-subtree.yml

@@ -43,27 +43,25 @@ jobs:
 
     - name: Update subtree/library locally
       run: |
-        git remote add upstream https://github.com/rust-lang/rust
-        git fetch upstream
+        pushd ..
+        git clone [email protected]:newren/git-filter-repo
+        git clone https://github.com/rust-lang/rust rust-tmp
+        cd rust-tmp
 
         # Ensure "upstream/master" branch contains the target commit
         if ! git show ${COMMIT_HASH} --oneline --no-patch; then
           echo "Rust commit ${COMMIT_HASH} cannot be found."
           exit 1
         fi
 
-        # subtree/library has the subtree-split variant of a commit that previously
-        # went into upstream/master. Running `git subtree split` on top of the
-        # original commit (i.e., the commit from upstream/master) is much faster (my experiment when working on 280k+
-        # commits: 113 seconds vs 613 seconds) than using the HEAD commit from
-        # subtree/library as base.
-        SUBTREE_HEAD=$(git log --format=%s -n 1 origin/subtree/library)
-        echo "SUBTREE_HEAD: ${SUBTREE_HEAD}"
-        UPSTREAM_ONTO=$(git log --grep="$SUBTREE_HEAD" -n 1 --format=%H upstream/master)
-        echo "UPSTREAM_ONTO: ${UPSTREAM_ONTO}"
-
         git checkout ${COMMIT_HASH}
-        git subtree split --prefix=library --onto $UPSTREAM_ONTO -b subtree/library
+        ../git-filter-repo/git-filter-repo --subdirectory-filter library --force
+        git checkout -b subtree/library
+        popd
+        git remote add rust-filtered ../rust-tmp/
+        git fetch rust-filtered
+        git checkout -b update-subtree/library rust-filtered/subtree/library
+        git rebase origin/subtree/library
 
     - name: Create Pull Request
       uses: peter-evans/create-pull-request@v7
@@ -83,7 +81,7 @@ jobs:
         git submodule update --init
 
         # This command may fail, which will require human intervention.
-        if ! git subtree merge --prefix=library subtree/library --squash; then
+        if ! git subtree merge --prefix=library update-subtree/library --squash; then
           echo "MERGE_CONFLICTS=yes" >> $GITHUB_ENV
           git commit -a -m "Merge from $COMMIT_HASH with conflicts"
         else