Continue format script when changes detected by clang-format-diff.py (#…

…12329)

Summary:
The original [clang-format-diff.py script](https://raw.githubusercontent.com/llvm/llvm-project/main/clang/tools/clang-format/clang-format-diff.py), referenced in format.sh, exits with a status of 1 at the end after writing diffs to stderr.  Consequently, the format.sh script terminates after initializing the 'diffs' variable.

Implemented additional logic in format-diff.sh to ensure continuous execution, even when changes are detected and further formatting is required.

Pull Request resolved: #12329

Reviewed By: pdillinger

Differential Revision: D53483185

Pulled By: cbi42

fbshipit-source-id: b7adff26f129220941258fd6ee83d053fa12b077

build_tools/format-diff.sh

@@ -137,18 +137,21 @@ then
   # should be relevant for formatting fixes.
   FORMAT_UPSTREAM_MERGE_BASE="$(git merge-base "$FORMAT_UPSTREAM" HEAD)"
   # Get the differences
-  diffs=$(git diff -U0 "$FORMAT_UPSTREAM_MERGE_BASE" | $CLANG_FORMAT_DIFF -p 1)
+  diffs=$(git diff -U0 "$FORMAT_UPSTREAM_MERGE_BASE" | $CLANG_FORMAT_DIFF -p 1) || true
   echo "Checking format of changes not yet in $FORMAT_UPSTREAM..."
 else
   # Check the format of uncommitted lines,
-  diffs=$(git diff -U0 HEAD | $CLANG_FORMAT_DIFF -p 1)
+  diffs=$(git diff -U0 HEAD | $CLANG_FORMAT_DIFF -p 1) || true
   echo "Checking format of uncommitted changes..."
 fi
 
 if [ -z "$diffs" ]
 then
   echo "Nothing needs to be reformatted!"
   exit 0
+elif [ $? -ne 1 ]; then
+  # CLANG_FORMAT_DIFF will exit on 1 while there is suggested changes.
+  exit $?
 elif [ $CHECK_ONLY ]
 then
   echo "Your change has unformatted code. Please run make format!"