From 9533532ce25563fa3a28bfb7acba09ac166490d7 Mon Sep 17 00:00:00 2001
From: Shea Levy <shea@shealevy.com>
Date: Wed, 25 Nov 2015 11:56:14 -0500
Subject: [PATCH] autoCallFunction: Auto-call functors

---
 src/libexpr/eval.cc | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index acf1fbdc1..df1600bc1 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1032,6 +1032,17 @@ void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
 {
     forceValue(fun);
 
+    if (fun.type == tAttrs) {
+        auto found = fun.attrs->find(sFunctor);
+        if (found != fun.attrs->end()) {
+            forceValue(*found->value);
+            Value * v = allocValue();
+            callFunction(*found->value, fun, *v, noPos);
+            forceValue(*v);
+            return autoCallFunction(args, *v, res);
+        }
+    }
+
     if (fun.type != tLambda || !fun.lambda.fun->matchAttrs) {
         res = fun;
         return;