From 59baaabb890540061cac6e0bd47817bc5429bb41 Mon Sep 17 00:00:00 2001
From: Michael Tautschnig <tautschn@amazon.com>
Date: Fri, 31 May 2019 11:03:06 +0000
Subject: [PATCH] Travis clang-format, cpplint: Use the merge base

We previously looked at the diff to the current head of the target
branch, which may have moved in comparison to the merge base of a pull
request. Thus we sometimes ended up with spurious clang-format errors,
talking about changes introduced in another PR.
---
 .travis.yml            | 4 +++-
 scripts/travis_lint.sh | 3 ++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index 5f84e2da9dd..f0e80827366 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -18,7 +18,9 @@ jobs:
         clang-format-7 --version
         # build a pathspec that excludes the files in .clang-format-ignore
         while read file ; do echo EXCLUDES+="':(top,exclude)$file' " ; done < .clang-format-ignore
-        git-clang-format-7 --binary clang-format-7 "${TRAVIS_BRANCH}" -- $EXCLUDES
+        MERGE_BASE=$(git merge-base ${TRAVIS_COMMIT_RANGE%...*} ${TRAVIS_COMMIT_RANGE#*...})
+        echo "Checking for formatting errors introduced since $MERGE_BASE"
+        git-clang-format-7 --binary clang-format-7 $MERGE_BASE -- $EXCLUDES
         git diff > formatted.diff
         if [[ -s formatted.diff ]] ; then
           echo 'Formatting error! The following diff shows the required changes'
diff --git a/scripts/travis_lint.sh b/scripts/travis_lint.sh
index 6592a3ebdfa..f7b80ed9327 100755
--- a/scripts/travis_lint.sh
+++ b/scripts/travis_lint.sh
@@ -12,5 +12,6 @@ else
   git config remote.origin.fetch +refs/heads/$TRAVIS_BRANCH:refs/remotes/origin/$TRAVIS_BRANCH
   git fetch --unshallow
   git checkout $TMP_HEAD
-  $script_folder/run_diff.sh CPPLINT origin/$TRAVIS_BRANCH # Check for errors compared to merge target
+  MERGE_BASE=$(git merge-base ${TRAVIS_COMMIT_RANGE%...*} ${TRAVIS_COMMIT_RANGE#*...})
+  $script_folder/run_diff.sh CPPLINT $MERGE_BASE
 fi