pass BASE_COMMIT to format_script.sh

It is not possible to use the base branch name in the GitHub Actions workflow to get the base SHA hash, because the branch name is not known there. To keep the format_script.sh universal, we just pass the SHA hash in from both the Travis and the GH Actions configurations instead.

.ci/format_script.sh

@@ -2,7 +2,6 @@
 
 set -ex
 
-BASE_COMMIT=$(git rev-parse $TRAVIS_BRANCH)
 echo "Running clang-format against branch $TRAVIS_BRANCH, with hash $BASE_COMMIT"
 COMMIT_FILES=$(git diff --name-only $BASE_COMMIT | grep -i -v LinkDef)
 RESULT_OUTPUT="$(git-clang-format --commit $BASE_COMMIT --diff --binary `which clang-format` $COMMIT_FILES)"

.github/workflows/code_analysis.yml

@@ -12,7 +12,7 @@ jobs:
     env:
       TRAVIS_BRANCH: ${{ github.base_ref }} 
       TRAVIS_PULL_REQUEST_BRANCH: ${{ github.head_ref }}
-      # BASE_COMMIT: ${{ github.event.pull_request.base.sha }}
+      BASE_COMMIT: ${{ github.event.pull_request.base.sha }}
     steps:
     - uses: actions/checkout@v2
     - name: Fetch base_ref HEAD

.travis.yml

@@ -23,7 +23,11 @@ matrix:
   include:
     - env: TOOL=clang-format
       script: &format_script
-        - if [ "$TRAVIS_PULL_REQUEST" != "false" ]; then .ci/format_script.sh; fi
+        - |
+          if [ "$TRAVIS_PULL_REQUEST" != "false" ]; then
+            export BASE_COMMIT=$(git rev-parse $TRAVIS_BRANCH)
+            .ci/format_script.sh
+          fi
 
     - env: TOOL=clang-tidy-analyzer
       before_script: &copy_headers