From: Philippe Proulx <eeppeliteloop@gmail.com>
Date: Thu, 27 Jan 2022 16:00:30 +0000 (-0500)
Subject: tools/format-cpp: enforce clang-format 13
X-Git-Url: http://git.efficios.com/?p=babeltrace.git;a=commitdiff_plain;h=9021ae77076ea1805eb09d0d93f8d1a4081b633c

tools/format-cpp: enforce clang-format 13

This patch updates `tools/format-cpp` so that if the `FORMATTER`
environment variable is not empty, the script tries to format with
`$FORMATTER`; otherwise, it tries `clang-format-13 -i` or, if not
available, `clang-format -i`.

In all cases, the script checks the major version of the selected
formatter with `--version`, failing before formatting if it's not 13.

Using exactly clang-format 13 is important for formatting consistency
across developers and CI systems because it's possible that a future
version of clang-format, given the same configuration file, formats
files dissimilarly.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: Ic81d8d09c35657b602de044f6123e8b11fc37c44
Reviewed-on: https://review.lttng.org/c/babeltrace/+/7151
---

diff --git a/tools/format-cpp b/tools/format-cpp
index 48703c29..370baef9 100755
--- a/tools/format-cpp
+++ b/tools/format-cpp
@@ -2,11 +2,56 @@
 #
 # SPDX-License-Identifier: GPL-2.0-only
 #
-# Copyright (C) 2020 Philippe Proulx <pproulx@efficios.com>
-
-FORMATTER="${FORMATTER:-clang-format -i}"
-root_dir="$(dirname "${BASH_SOURCE[0]}")/.."
-find "$root_dir" \( -name '*.cpp' -o -name '*.hpp' \) \
-	! -wholename '*/cpp-common/optional.hpp' \
-	! -wholename '*/cpp-common/string_view.hpp' \
-	-exec $FORMATTER '{}' ';'
+# Copyright (C) 2020-2022 Philippe Proulx <pproulx@efficios.com>
+
+expected_formatter_major_version=13
+
+# Runs the formatter, making sure it's the expected version.
+format_cpp() {
+	local formatter=$1
+	local version
+
+	version=$($formatter --version)
+
+        # shellcheck disable=SC2181
+	if (($? != 0)); then
+		echo "Cannot execute \`$formatter --version\`." >&2
+		return 1
+	fi
+
+	if [[ "$version" != *"clang-format version $expected_formatter_major_version"* ]]; then
+		echo "Expecting clang-format $expected_formatter_major_version." >&2
+		echo >&2
+		echo Got: >&2
+		echo >&2
+		echo "$version" >&2
+		return 1
+	fi
+
+	local root_dir
+
+	root_dir="$(dirname "${BASH_SOURCE[0]}")/.."
+
+	# Using xargs to fail as soon as the formatter fails (`-exec`
+	# won't stop if its subprocess fails).
+	#
+	# shellcheck disable=SC2086
+	find "$root_dir" \( -name '*.cpp' -o -name '*.hpp' \) \
+		! -wholename '*/cpp-common/optional.hpp' \
+		! -wholename '*/cpp-common/string_view.hpp' \
+		-print0 | xargs -n1 -0 $formatter
+}
+
+if [[ -n "$FORMATTER" ]]; then
+	# Try using environment-provided formatter
+	formatter=$FORMATTER
+elif command -v clang-format-$expected_formatter_major_version &> /dev/null; then
+	# Try using the expected version of clang-format
+	formatter="clang-format-$expected_formatter_major_version -i"
+else
+	# Try using `clang-format` as is
+	formatter='clang-format -i'
+fi
+
+# Try to format files
+format_cpp "$formatter"