From 3130aafd0145c5c07f4557fe37f0c4d367e2d4f1 Mon Sep 17 00:00:00 2001
From: Robin Gloster <mail@glob.in>
Date: Sun, 27 Oct 2019 10:15:51 +0100
Subject: builtins.toJSON: fix __toString usage

(cherry picked from commit e583df52800b4baa1564b027fe3b83a21756c2cc)
---
 src/libexpr/eval.hh | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'src/libexpr/eval.hh')

diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 22472fd726b2..61ee4a73b563 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -9,6 +9,7 @@
 #include "function-trace.hh"
 
 #include <map>
+#include <optional>
 #include <unordered_map>
 
 
@@ -196,6 +197,9 @@ public:
        set with attribute `type = "derivation"'). */
     bool isDerivation(Value & v);
 
+    std::optional<string> tryAttrsToString(const Pos & pos, Value & v,
+        PathSet & context, bool coerceMore = false, bool copyToStore = true);
+
     /* String coercion.  Converts strings, paths and derivations to a
        string.  If `coerceMore' is set, also converts nulls, integers,
        booleans and lists to a string.  If `copyToStore' is set,
-- 
cgit 1.4.1