diff --git a/.github/workflows/pr_info.yml b/.github/workflows/pr_info.yml
new file mode 100644
index 0000000..66ee441
--- /dev/null
+++ b/.github/workflows/pr_info.yml
@@ -0,0 +1,69 @@
+name: PR Info
+
+# This workflow builds the whole project once and:
+# - comments build deprecations/warnings (highlighting new ones since last tested PR)
+
+on:
+  pull_request:
+    branches:
+      - master
+      - stable
+
+jobs:
+  pr_info:
+    name: PR Info
+    runs-on: ubuntu-20.04
+    steps:
+    - name: 'Prepare sticky comment'
+      # commit of v2.5.0
+      # same one used again at the bottom of the file to update the comment.
+      uses: marocchino/sticky-pull-request-comment@3d60a5b2dae89d44e0c6ddc69dd7536aec2071cd
+      with:
+        message: |
+          Thanks for your Pull Request and making D better!
+
+          This comment will automatically be updated to summarize some statistics in a few minutes.
+        only_create: true
+
+    - name: '[Linux] Install dependencies'
+      if: runner.os == 'Linux'
+      run: |
+        sudo apt-get update && sudo apt-get install -y libcurl4-openssl-dev netcat
+
+    # Compiler to test with
+    - name: Prepare compiler
+      uses: dlang-community/setup-dlang@v1
+      with:
+        compiler: ldc-latest
+
+    - name: Checkout
+      uses: actions/checkout@v3
+      with:
+        fetch-depth: 0
+
+    - name: Checkout old stuff, with new comment script
+      run: |
+        git checkout ${{ github.base_ref }}
+        git checkout ${{ github.sha }} -- ./scripts/ci/summary_comment.sh ./scripts/ci/summary_comment_diff.sh
+
+    # first dump old info
+
+    - name: Check pre-PR status
+      run: ./scripts/ci/summary_comment.sh | tee ../OLD_OUTPUT.txt
+
+    - name: Checkout PR target
+      run: |
+        git checkout ${{ github.sha }}
+        git clean -fd
+        git reset --hard
+
+    - name: Evaluate PR
+      run: ./scripts/ci/summary_comment.sh | tee ../NEW_OUTPUT.txt
+
+    - name: Generate comment
+      run: ./scripts/ci/summary_comment_diff.sh ../OLD_OUTPUT.txt ../NEW_OUTPUT.txt | tee comment.txt
+
+    - name: Update GitHub comment
+      uses: marocchino/sticky-pull-request-comment@3d60a5b2dae89d44e0c6ddc69dd7536aec2071cd
+      with:
+        path: comment.txt
diff --git a/scripts/ci/summary_comment.sh b/scripts/ci/summary_comment.sh
new file mode 100755
index 0000000..fb1f2bf
--- /dev/null
+++ b/scripts/ci/summary_comment.sh
@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+set -u
+
+# Output from this script is piped to a file by CI, being run from before a
+# change has been made and after a change has been made. Then both outputs are
+# compared using summary_comment_diff.sh
+
+# cd to git folder, just in case this is manually run:
+ROOT_DIR="$( cd "$(dirname "${BASH_SOURCE[0]}")/../../" && pwd )"
+cd ${ROOT_DIR}
+
+dub --version
+ldc2 --version
+
+# fetch missing packages before timing
+dub upgrade --missing-only
+
+start=`date +%s`
+dub build --build=release --force 2>&1 || echo "BUILD FAILED"
+end=`date +%s`
+build_time=$( echo "$end - $start" | bc -l )
+
+strip bin/dub
+
+echo "STAT:statistics (-before, +after)"
+echo "STAT:executable size=$(wc -c bin/dub)"
+echo "STAT:rough build time=${build_time}s"
diff --git a/scripts/ci/summary_comment_diff.sh b/scripts/ci/summary_comment_diff.sh
new file mode 100755
index 0000000..4831abe
--- /dev/null
+++ b/scripts/ci/summary_comment_diff.sh
@@ -0,0 +1,111 @@
+#!/usr/bin/env bash
+
+set -u
+
+EMPTY=1
+
+ADDED=$(diff --new-line-format='%L' --old-line-format='' --unchanged-line-format='' "$1" "$2")
+REMOVED=$(diff --new-line-format='' --old-line-format='%L' --unchanged-line-format='' "$1" "$2")
+TOTAL=$(cat "$2")
+
+STATS_OLD=$(grep -E '^STAT:' "$1" | sed -E 's/^STAT://')
+STATS_NEW=$(grep -E '^STAT:' "$2" | sed -E 's/^STAT://')
+
+STATS_DIFFED=$(diff --new-line-format='+%L' --old-line-format='-%L' --unchanged-line-format=' %L' <(echo "$STATS_OLD") <(echo "$STATS_NEW"))
+
+ADDED_DEPRECATIONS=$(grep -Pi '\b(deprecation|deprecated)\b' <<< "$ADDED")
+REMOVED_DEPRECATIONS=$(grep -Pi '\b(deprecation|deprecated)\b' <<< "$REMOVED")
+ADDED_WARNINGS=$(grep -Pi '\b(warn|warning)\b' <<< "$ADDED")
+REMOVED_WARNINGS=$(grep -Pi '\b(warn|warning)\b' <<< "$REMOVED")
+
+DEPRECATION_COUNT=$(grep -Pi '\b(deprecation|deprecated)\b' <<< "$TOTAL" | wc -l)
+WARNING_COUNT=$(grep -Pi '\b(warn|warning)\b' <<< "$TOTAL" | wc -l)
+
+if [ -z "$ADDED_DEPRECATIONS" ]; then
+	# no new deprecations
+	true
+else
+	echo "⚠️ This PR introduces new deprecations:"
+	echo
+	echo '```'
+	echo "$ADDED_DEPRECATIONS"
+	echo '```'
+	echo
+	EMPTY=0
+fi
+
+if [ -z "$ADDED_WARNINGS" ]; then
+	# no new deprecations
+	true
+else
+	echo "⚠️ This PR introduces new warnings:"
+	echo
+	echo '```'
+	echo "$ADDED_WARNINGS"
+	echo '```'
+	echo
+	EMPTY=0
+fi
+
+if grep "BUILD FAILED" <<< "$TOTAL"; then
+	echo '❌ Basic `dub build` failed! Please check your changes again.'
+	echo
+else
+	if [ -z "$REMOVED_DEPRECATIONS" ]; then
+		# no removed deprecations
+		true
+	else
+		echo "✅ This PR fixes following deprecations:"
+		echo
+		echo '```'
+		echo "$REMOVED_DEPRECATIONS"
+		echo '```'
+		echo
+		EMPTY=0
+	fi
+
+	if [ -z "$REMOVED_WARNINGS" ]; then
+		# no removed warnings
+		true
+	else
+		echo "✅ This PR fixes following warnings:"
+		echo
+		echo '```'
+		echo "$REMOVED_WARNINGS"
+		echo '```'
+		echo
+		EMPTY=0
+	fi
+
+	if [ $EMPTY == 1 ]; then
+		echo "✅ PR OK, no changes in deprecations or warnings"
+		echo
+	fi
+
+	echo "Total deprecations: $DEPRECATION_COUNT"
+	echo
+	echo "Total warnings: $WARNING_COUNT"
+	echo
+fi
+
+if [ -z "$STATS_DIFFED" ]; then
+	# no statistics?
+	true
+else
+	echo "Build statistics:"
+	echo
+	echo '```diff'
+	echo "$STATS_DIFFED"
+	echo '```'
+	echo
+fi
+
+echo '<details>'
+echo
+echo '<summary>Full build output</summary>'
+echo
+echo '```'
+echo "$TOTAL"
+echo '```'
+echo
+echo '</details>'