Added CI script for automatically rebasing onto nightly.

Author: icmccorm

.github/workflows/sync.yml renamed to .github/workflows/nightly.yml

@@ -1,4 +1,4 @@
-name: sync
+name: nightly
 on: workflow_dispatch
 permissions:
   contents: read
@@ -21,7 +21,12 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
+      - name: Install LLVM
+        run: |
+          sudo apt-get install llvm
+      - name: Install ninja
+        run: sudo apt-get install ninja-build
       - name: Rebase
         run: src/ci/scripts/sync.sh
       - name: Build
-        run: ./x.py build --stage 1 library
+        run: ./x.py build --stage 1 library --set llvm.download-ci-llvm=false

src/ci/scripts/sync.sh

@@ -1,10 +1,12 @@
 #!/bin/bash
 ORIGIN="https://github.com/rust-lang"
+LLVM_FORK="https://github.com/borrow-sanitizer/llvm-project.git"
 RUST_UPSTREAM="$ORIGIN/rust.git"
 LLVM_UPSTREAM="$ORIGIN/llvm-project.git"
-BRANCH="bsan"
-
-git checkout $BRANCH || exit
+MAIN_BRANCH="bsan"
+BASE_TAG="base"
+BASE_COMMIT=$(git rev-list -n 1 $BASE_TAG)
+git checkout "$MAIN_BRANCH" || exit
 
 init_upstream() {
     local upstream=$1
@@ -32,17 +34,16 @@ fi
 
 NIGHTLY_TOOLCHAIN="nightly-$DATE"
 git submodule update --init --no-recommend-shallow src/llvm-project 
-
 (cd src/llvm-project && init_upstream $LLVM_UPSTREAM)
 init_upstream $RUST_UPSTREAM
-git branch -D nightly &> /dev/null
+git branch -D nightly
 git checkout -b nightly "$NIGHTLY_COMMIT_HASH" || exit
-
 git submodule update --rebase src/llvm-project
-if ! git diff-index --quiet HEAD --; then
-    git add src/llvm-project
-    git commit -m "$NIGHTLY_TOOLCHAIN"
-fi
-
-git checkout $BRANCH || exit
-git rebase nightly || exit
+git submodule set-url -- src/llvm-project $LLVM_FORK
+git submodule set-branch --branch $MAIN_BRANCH -- src/llvm-project 
+git add src/llvm-project .gitmodules
+git commit -m "$NIGHTLY_TOOLCHAIN"
+git tag -D $BASE_TAG
+git tag -a $BASE_TAG -m "$NIGHTLY_TOOLCHAIN"
+git checkout "$MAIN_BRANCH" || exit
+git rebase --onto nightly "$BASE_COMMIT" $MAIN_BRANCH || exit