Workflow for cargo bloat (#462)

* adds cargo bloat workflow

* uses notice instead

* warning for bigger sizes, ignore equal sizes

* DO NOT MERGE, TEST COMMIT

* reverted test commit

.github/workflows/bloat_formatter.sh

@@ -0,0 +1,46 @@
+#!/bin/bash
+# Copyright 2022 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+cd "$(dirname "$0")"
+
+# New output file is $1
+# Old output file is $2
+TMP=comment.md
+WARNING="Note: numbers above are a result of guesswork. They are not 100% correct and never will be."
+NEW_SIZE=$(cat "$1" | sed -nr 's/.*100.0% (.*)KiB .text.*/\1/p')
+OLD_SIZE=$(cat "$2" | sed -nr 's/.*100.0% (.*)KiB .text.*/\1/p')
+
+echo "
+OLD $OLD_SIZE kiB
+NEW $NEW_SIZE kiB" > "$TMP"
+
+echo "
+Output of cargo bloat
+======================
+" >> "$TMP"
+
+echo "Including PR" >> "$TMP"
+cat "$1" >> "$TMP"
+echo "Base branch" >> "$TMP"
+cat "$2" >> "$TMP"
+
+COMMENT="$(cat $TMP | sed "s/$WARNING//g" | sed 's/%/%25/g' | sed -z 's/\n/%0A/g')"
+# No output for equality is intentional.
+if (( $(echo "$NEW_SIZE > $OLD_SIZE" | bc -l) )); then
+  echo "::warning file=.github/workflows/cargo_bloat.yml,title=Binary size::$COMMENT"
+fi
+if (( $(echo "$NEW_SIZE < $OLD_SIZE" | bc -l) )); then
+  echo "::notice file=.github/workflows/cargo_bloat.yml,title=Binary size::$COMMENT"
+fi