From c2db54eaae2bc2bba5a76efc11ed84bdf88b609f Mon Sep 17 00:00:00 2001
From: Johannes Schilling <dario@deaktualisierung.org>
Date: Sat, 28 May 2022 12:21:49 +0200
Subject: [PATCH 1/2] Add script to update toolchain version everywhere

This should keep toolchain versions consistent, and prevent forgetting
to update it in one of the places.
---
 .github/workflows/style.yml |  2 +-
 scripts/toolchain-version   | 49 +++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)
 create mode 100755 scripts/toolchain-version

diff --git a/.github/workflows/style.yml b/.github/workflows/style.yml
index c7b90e1e..f9b0bd08 100644
--- a/.github/workflows/style.yml
+++ b/.github/workflows/style.yml
@@ -21,7 +21,7 @@ jobs:
       - name: Shellcheck
         run: |
           shellcheck --version
-          shellcheck ci/*.sh
+          shellcheck ci/*.sh scripts/toolchain-version
 
       - name: Update nightly
         run: |
diff --git a/scripts/toolchain-version b/scripts/toolchain-version
new file mode 100755
index 00000000..2bc1233f
--- /dev/null
+++ b/scripts/toolchain-version
@@ -0,0 +1,49 @@
+#!/bin/bash
+
+set -eu
+
+
+NIGHTLY_RE="nightly-[0-9]{4}-[0-9]{2}-[0-9]{2}"
+
+nightly_mentions() {
+    grep -Eo "$NIGHTLY_RE" "$1" | sort --unique
+}
+
+check_versions_match() {
+    readarray -t versions_readme < <(nightly_mentions README.md)
+    if [[ "${#versions_readme[@]}" -gt 1 ]]; then
+        echo "Multiple different nightly versions mentioned in README.md: ${versions_readme[*]}"
+        exit 1
+    fi
+
+    version_toolchain=$(nightly_mentions rust-toolchain)
+    if [[ "${versions_readme[0]}" != "${version_toolchain}" ]]; then
+        echo "Toolchain nightly version does not match README.md: ${version_toolchain} vs. ${versions_readme[0]}"
+        exit 1
+    fi
+}
+
+update_version_everywhere() {
+    if ! echo "$1" | grep -Eq "$NIGHTLY_RE"; then
+        echo "That doesn't look like a nightly version to me: '$1'"
+        exit 1
+    fi
+
+    sed -i -E -e "s#${NIGHTLY_RE}#$1#g" README.md rust-toolchain
+}
+
+
+while getopts "cu:" opt; do
+    case $opt in
+        c)
+            check_versions_match
+            ;;
+        u)
+            update_version_everywhere "$OPTARG"
+            ;;
+        *)
+            echo "Usage: $0 [-c | -u <nightly version> ]"
+            exit 1
+            ;;
+    esac
+done

From d6fd3b859bf99fe3897e04ca30f3dd8004416b60 Mon Sep 17 00:00:00 2001
From: Johannes Schilling <dario@deaktualisierung.org>
Date: Sat, 28 May 2022 12:25:46 +0200
Subject: [PATCH 2/2] Add github workflow for toolchain consistency check

Implements #308
---
 .github/workflows/style.yml | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/.github/workflows/style.yml b/.github/workflows/style.yml
index f9b0bd08..7dfaf353 100644
--- a/.github/workflows/style.yml
+++ b/.github/workflows/style.yml
@@ -38,3 +38,12 @@ jobs:
           if rustup component add clippy rustc-dev; then
               cargo clippy --all
           fi
+
+  version_consistency_check:
+    name: Toolchain version consistency check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Toolchain version consistency check
+        run: scripts/toolchain-version -c
+