From dd73b1ab64748ca623306205d0853d3ad67ed717 Mon Sep 17 00:00:00 2001
From: Thomas Spriggs <thomas.spriggs@diffblue.com>
Date: Tue, 17 Apr 2018 16:24:15 +0100
Subject: [PATCH] Specify default hash function of `dstringt` to STL.

This provides a default hash function of `dstringt` to STL. Which means
that the hash function no longer needs to be specified when declaring
instances of STL containers where `dstringt` is used as the key.
---
 src/util/dstring.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/util/dstring.h b/src/util/dstring.h
index d7b2c76409d..91c58a39f38 100644
--- a/src/util/dstring.h
+++ b/src/util/dstring.h
@@ -175,4 +175,18 @@ inline std::ostream &operator<<(std::ostream &out, const dstringt &a)
   return a.operator<<(out);
 }
 
+// NOLINTNEXTLINE [allow specialisation within 'std']
+namespace std
+{
+/// Default hash function of `dstringt` for use with STL containers.
+template <>
+struct hash<dstringt> // NOLINT(readability/identifiers)
+{
+  size_t operator()(const dstringt &dstring) const
+  {
+    return dstring.hash();
+  }
+};
+}
+
 #endif // CPROVER_UTIL_DSTRING_H