be-code-style

What I do

Fix C++ code formatting issues in the BE and Cloud modules using the project's clang-format configuration (v16).

When to use me

• Before committing BE/Cloud C++ code changes
• When CI reports clang-format failures
• When you need to check or fix C++ code style

Prerequisites

You need to confirm that the major version of the called clang-format is 16. If the current environment's default does not meet this requirement, try the following:

1. If .vscode/settings.json exists, use the clang-format.executable item in it.
2. If it is a worktree directory, use the .vscode/settings.json from the main directory.
3. Check the path to the compiler toolchain by trying to find it from the PATH environment variable, the current directory, and the main directory's custom_env.sh. Look for a clang-format with the major version number 16 in that path and its parent directory.

Procedure

Step 1: Auto-fix formatting

Run the project's formatting script, which enforces clang-format v16:

build-support/clang-format.sh

This formats all C++ files under be/src, be/test, cloud/src, cloud/test in-place, respecting .clang-format and .clang-format-ignore.

Important: Always use this script instead of invoking clang-format directly. The script checks that clang-format version 16 is installed and exits with an error if the wrong version is found. Using a different version will produce inconsistent formatting.

Step 2: Check-only (no modification)

To verify formatting without modifying files:

build-support/check-format.sh

This outputs a diff of any formatting violations and exits non-zero if there are any.

Step 3: Review and commit

After running clang-format.sh, review the changes with git diff to verify only formatting was changed, then stage and commit.

Key Configuration

File	Purpose
.clang-format	Main formatting rules (Google-based, 100 col, 4-space indent)
.clang-format-ignore	Files excluded from formatting (third-party, generated)
build-support/run_clang_format.py	Python wrapper for parallel execution

Excluded Directories

The following are excluded from formatting (see .clang-format-ignore):

• be/src/apache-orc/*, be/src/clucene/*, be/src/gutil/*
• be/src/glibc-compatibility/*
• Specific third-party vendored files (mustache, sse2neon, utf8_check)
• cloud/src/common/defer.h

Troubleshooting

Problem	Solution
clang-format not found	Install clang-format v16 or set CLANG_FORMAT_BINARY env var
version is not 16	Install clang-format v16; on macOS: brew install llvm@16
Files not being formatted	Check .clang-format-ignore for exclusions