From ff7585295fd291e523eb1f4eb798a968be014cbc Mon Sep 17 00:00:00 2001
From: Josh Soref <2119212+jsoref@users.noreply.github.com>
Date: Wed, 27 Nov 2024 19:49:50 -0500
Subject: [PATCH] Ask dhall lint to show its cards

`dhall lint --check` appears to be inconsistently opinionated.

Instead, get a baseline, ask `dhall lint` to rewrite files, and then compare the
state of the world before/after, and finally compare the files that dhall lint
potentially rewrote.
---
 check.sh     | 5 ++---
 dhall-linter | 9 +++++++++
 2 files changed, 11 insertions(+), 3 deletions(-)
 create mode 100755 dhall-linter

diff --git a/check.sh b/check.sh
index 2e9f030..bca9027 100755
--- a/check.sh
+++ b/check.sh
@@ -36,12 +36,11 @@ fi
 
 if [ -n "$LINT" ]; then
   echo "::group::lint"
-  if cat "$LIST" | xargs -0 dhall lint --check; then
-    echo '::notice::Linting passed.'
-  else
+  if ! cat "$LIST" | xargs -0 "$GITHUB_ACTION_PATH/dhall-linter"; then
     echo '::error::Linting failed. Use `dhall lint` locally to fix the errors.'
     exit 1
   fi
+  echo '::notice::Linting passed.'
   echo "::endgroup::"
 fi
 
diff --git a/dhall-linter b/dhall-linter
new file mode 100755
index 0000000..f1559a6
--- /dev/null
+++ b/dhall-linter
@@ -0,0 +1,9 @@
+#!/bin/sh
+baseline=$(mktemp)
+git status > "$baseline" || true
+dhall lint "$@"
+updated=$(mktemp)
+git status > "$updated" || true
+diff -u "$baseline" "$updated" || true
+echo
+git diff --exit-code -- "$@"