make Finally more local

no need for function<> with c++17 deduction. this saves allocations and virtual
calls, but has the same semantics otherwise. not going through function has the
side effect of giving compilers more insight into the cleanup code, so we need a
few local warning disables.

1 files changed, 3 insertions, 4 deletions

diff --git a/src/libutil/finally.hh b/src/libutil/finally.hh
index 7760cfe9a..dee2e8d2f 100644
--- a/src/libutil/finally.hh
+++ b/src/libutil/finally.hh
@@ -1,14 +1,13 @@
 #pragma once
 
-#include <functional>
-
 /* A trivial class to run a function at the end of a scope. */
+template<typename Fn>
 class Finally
 {
 private:
-    std::function<void()> fun;
+    Fn fun;
 
 public:
-    Finally(std::function<void()> fun) : fun(fun) { }
+    Finally(Fn fun) : fun(std::move(fun)) { }
     ~Finally() { fun(); }
 };