docs/updating_clang_format_binaries.md

# Updating Clang format binaries

Instructions on how to update the [clang-format binaries](clang_format.md) that
come with a checkout of Chromium.

## Prerequisites

You'll also need permissions to upload to the appropriate google storage
bucket. Chromium infrastructure team members have this, and others can be
granted the permission based on need. If you need this permission, mention this
in the tracking bug.

## Fetch and upload prebuilt clang-format binaries from recent clang rolls

Recent clang rolls can be found via looking at the history of
[update.py](https://crsrc.org/c/tools/clang/scripts/update.py). You can also
use clang-format packages built in recent successful dry run attempts at
updating clang as mentioned [here](clang_sheriffing.md).

The following will, for each supported host architecture,

* Fetch the corresponding clang-format package from the specified clang roll
* Extract and copy the clang-format binary to the proper directory
* Upload the binary into a publicly accessible google storage bucket, also
  updating the corresponding `.sha1` files in the local checkout of Chrome

```shell
cd $SRC/chromium/src

GS_PATH=gs://chromium-browser-clang-staging
CLANG_REV=llvmorg-15-init-234-g567890abc-2

echo Linux
gsutil cp $GS_PATH/Linux_x64/clang-format-$CLANG_REV.tgz /tmp
tar xf /tmp/clang-format-$CLANG_REV.tgz -C buildtools/linux64 --strip-component=1 bin/clang-format

echo Win
gsutil cp $GS_PATH/Win/clang-format-$CLANG_REV.tgz /tmp
tar xf /tmp/clang-format-$CLANG_REV.tgz -C buildtools/win --strip-component=1 bin/clang-format.exe

echo 'Mac x64'
gsutil cp $GS_PATH/Mac/clang-format-$CLANG_REV.tgz /tmp
tar xf /tmp/clang-format-$CLANG_REV.tgz -C buildtools/mac --strip-component=1 bin/clang-format
mv buildtools/mac/clang-format buildtools/mac/clang-format.x64

echo 'Mac arm64'
gsutil cp $GS_PATH/Mac_arm64/clang-format-$CLANG_REV.tgz /tmp
tar xf /tmp/clang-format-$CLANG_REV.tgz -C buildtools/mac --strip-component=1 bin/clang-format
mv buildtools/mac/clang-format buildtools/mac/clang-format.arm64

echo 'Uploading to GCS and creating sha1 files'
upload_to_google_storage.py --bucket=chromium-clang-format buildtools/linux64/clang-format
upload_to_google_storage.py --bucket=chromium-clang-format buildtools/win/clang-format.exe
upload_to_google_storage.py --bucket=chromium-clang-format buildtools/mac/clang-format.x64
upload_to_google_storage.py --bucket=chromium-clang-format buildtools/mac/clang-format.arm64

# Clean up
rm /tmp/clang-format-$CLANG_REV.tgz
# These aren't in .gitignore because these mac per-arch paths only exist when updating clang-format.
# gclient runhooks puts these binaries at buildtools/mac/clang-format.
rm buildtools/mac/clang-format.x64 buildtools/mac/clang-format.arm64
```

## Upload a CL according to the following template

    Update clang-format binaries and scripts for all platforms.

    I followed these instructions:
    https://chromium.googlesource.com/chromium/src/+/main/docs/updating_clang_format_binaries.md

    The binaries were built at clang revision ####### on ##CRREV##.

    Bug:

The change should **always** include new `.sha1` files for each platform (we
want to keep these in lockstep), should **never** include `clang-format`
binaries directly. The change should **always** update `README.chromium`

clang-format binaries should weigh in at 1.5MB or less. Watch out for size
regressions.