From 06957af4715df7eb6b447c75a1c0180b58c8accb Mon Sep 17 00:00:00 2001
From: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Date: Wed, 2 Dec 2020 18:06:24 +0100
Subject: [PATCH] QDuplicateTracker: allow usage of qHash

The codepath using unordered_set forced the usage of std::hash,
which isn't provided by many Qt types. Instead, use the
brand new helpers in QHash that dispatch to qHash with a fallback
on std::hash.

Change-Id: I9185fe9c52de05c470afe7466007591977e65bb1
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/tools/qduplicatetracker_p.h | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/corelib/tools/qduplicatetracker_p.h b/src/corelib/tools/qduplicatetracker_p.h
index 817d259d23..c21b67ffa3 100644
--- a/src/corelib/tools/qduplicatetracker_p.h
+++ b/src/corelib/tools/qduplicatetracker_p.h
@@ -55,6 +55,7 @@
 #if QT_HAS_INCLUDE(<memory_resource>) && __cplusplus > 201402L
 #  include <unordered_set>
 #  include <memory_resource>
+#  include <qhash.h> // for the hashing helpers
 #else
 #  include <qset.h>
 #endif
@@ -64,9 +65,16 @@ QT_BEGIN_NAMESPACE
 template <typename T, size_t Prealloc = 32>
 class QDuplicateTracker {
 #ifdef __cpp_lib_memory_resource
+    template <typename HT>
+    struct QHasher {
+        size_t operator()(const HT &t) const {
+            return QHashPrivate::calculateHash(t, qGlobalQHashSeed());
+        }
+    };
+
     char buffer[Prealloc * sizeof(T)];
     std::pmr::monotonic_buffer_resource res{buffer, sizeof buffer};
-    std::pmr::unordered_set<T> set{&res};
+    std::pmr::unordered_set<T, QHasher<T>> set{&res};
 #else
     QSet<T> set;
     int setSize = 0;