Automatically generate release notes draft during proposal

.github/release-notes.sh

@@ -0,0 +1,63 @@
+#!/bin/sh
+
+scratch=$(mktemp -d -t tmp.XXXXXXXXXX)
+finish() {
+  rm -rf "$scratch"
+}
+trap finish EXIT
+
+DATE=$(date +%Y-%m-%d)
+DETERMINATE_NIX_VERSION=$(cat .version-determinate)
+TAG_NAME="v${DETERMINATE_NIX_VERSION}"
+NIX_VERSION=$(cat .version)
+NIX_VERSION_MAJOR_MINOR=$(echo "$NIX_VERSION" | cut -d. -f1,2)
+GITHUB_REPOSITORY="${GITHUB_REPOSITORY:-DeterminateSystems/nix-src}"
+
+gh api "/repos/${GITHUB_REPOSITORY}/releases/generate-notes" \
+        -f "tag_name=${TAG_NAME}" > "$scratch/notes.json"
+
+trim_trailing_newlines() {
+    tac \
+        | awk 'flag {print} {if(NF) flag=1}' \
+        | tac
+}
+
+linkify_gh() {
+    sed \
+        -e 's#\(https://github.com/DeterminateSystems/nix-src/\(pull\|issue\)/\([[:digit:]]\+\)\)#[dnix\#\3](\1)#' \
+        -e 's#\(https://github.com/DeterminateSystems/nix-src/compare/\([^ ]\+\)\)#[\2](\1)#'
+}
+
+(
+    cat doc/manual/source/release-notes-determinate/changes.md \
+        | sed 's/^.*\(<!-- differences -->\)$/This section lists the differences between upstream Nix '"$NIX_VERSION_MAJOR_MINOR"' and Determinate Nix '"$DETERMINATE_NIX_VERSION"'.\1/' \
+
+    printf "\n<!-- Determinate Nix version %s -->\n" "$DETERMINATE_NIX_VERSION"
+    cat "$scratch/notes.json" \
+        | jq -r .body \
+        | grep -v '^#' \
+        | grep -v "Full Changelog" \
+        | trim_trailing_newlines \
+        | sed -e 's/^\* /\n* /' \
+        | linkify_gh
+) > "$scratch/changes.md"
+
+(
+    printf "# Release %s (%s)\n\n" \
+        "$DETERMINATE_NIX_VERSION" \
+        "$DATE"
+    printf "* Based on [upstream Nix %s](../release-notes/rl-%s.md).\n\n" \
+        "$NIX_VERSION" \
+        "$NIX_VERSION_MAJOR_MINOR"
+
+    cat "$scratch/notes.json" | jq -r .body | linkify_gh
+) > "$scratch/rl.md"
+
+(
+    cat doc/manual/source/SUMMARY.md.in \
+        | sed 's/\(<!-- next -->\)$/\1\n  - [Release '"$DETERMINATE_NIX_VERSION"' ('"$DATE"')](release-notes-determinate\/rl-'"$DETERMINATE_NIX_VERSION"'.md)/'
+) > "$scratch/summary.md"
+
+mv "$scratch/changes.md" doc/manual/source/release-notes-determinate/changes.md
+mv "$scratch/rl.md" "doc/manual/source/release-notes-determinate/rl-${DETERMINATE_NIX_VERSION}.md"
+mv "$scratch/summary.md" doc/manual/source/SUMMARY.md.in

.github/workflows/propose-release.yml

@@ -26,4 +26,6 @@ jobs:
       extra-commands-early: |
         echo ${{ inputs.version }} > .version-determinate
         git add .version-determinate
+        ./.github/release-notes.sh
+        git add doc
         git commit -m "Set .version-determinate to ${{ inputs.version }}" || true