From 87f07835889b686aca1fb3733c2aa2d61586c1e1 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Fri, 22 Aug 2025 16:56:55 -0700
Subject: [PATCH] Enforce that required toolchain input is provided

---
 action.yml | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/action.yml b/action.yml
index c68a596..b48984a 100644
--- a/action.yml
+++ b/action.yml
@@ -33,7 +33,11 @@ runs:
     - id: parse
       run: |
         : parse toolchain version
-        if [[ $toolchain =~ ^stable' '[0-9]+' '(year|month|week|day)s?' 'ago$ ]]; then
+        if [[ -z $toolchain ]]; then
+          # GitHub does not enforce `required: true` inputs itself. https://github.com/actions/runner/issues/1070
+          echo "'toolchain' is a required input" >&2
+          exit 1
+        elif [[ $toolchain =~ ^stable' '[0-9]+' '(year|month|week|day)s?' 'ago$ ]]; then
           if [[ ${{runner.os}} == macOS ]]; then
             echo "toolchain=1.$((($(date -v-$(sed 's/stable \([0-9]*\) \(.\).*/\1\2/' <<< $toolchain) +%s)/60/60/24-16569)/7/6))" >> $GITHUB_OUTPUT
           else