From 76aced691552e193e0225af40f8acf484cfeaefe Mon Sep 17 00:00:00 2001
From: Jade Lovelace <software@lfcode.ca>
Date: Mon, 26 Feb 2024 01:21:54 -0800
Subject: [PATCH] finally.hh: delete copy constructor which is a bad idea

---
 src/libutil/finally.hh | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/libutil/finally.hh b/src/libutil/finally.hh
index 4cae20a36..f9f0195a1 100644
--- a/src/libutil/finally.hh
+++ b/src/libutil/finally.hh
@@ -11,8 +11,15 @@ class [[nodiscard("Finally values must be used")]] Finally
 {
 private:
     Fn fun;
+    bool movedFrom = false;
 
 public:
     Finally(Fn fun) : fun(std::move(fun)) { }
-    ~Finally() { fun(); }
+    // Copying Finallys is definitely not a good idea and will cause them to be
+    // called twice.
+    Finally(Finally &other) = delete;
+    Finally(Finally &&other) : fun(std::move(other.fun)) {
+        other.movedFrom = true;
+    }
+    ~Finally() { if (!movedFrom) fun(); }
 };