From 45fd36f1480a6229879a4e59236ffa1d1d22dfbf Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Mon, 5 Feb 2024 15:53:39 -0800
Subject: [PATCH] qHash: make hashing of QLatin1StringView be the same as
 QString
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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Everywhere, except for ARM.

Change-Id: I50e2158aeade4256ad1dfffd17b11ca2d57ad1fb
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
---
 src/corelib/tools/qhash.cpp                           | 11 +----------
 src/corelib/tools/qhashfunctions.h                    |  6 ++++++
 .../tools/qhashfunctions/tst_qhashfunctions.cpp       |  2 +-
 3 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/src/corelib/tools/qhash.cpp b/src/corelib/tools/qhash.cpp
index 87ccc46d71..af393b9235 100644
--- a/src/corelib/tools/qhash.cpp
+++ b/src/corelib/tools/qhash.cpp
@@ -1140,21 +1140,12 @@ size_t qHash(QLatin1StringView key, size_t seed) noexcept
     // the seed is always 0 in bootstrapped mode (no seed generation code),
     // so help the compiler do dead code elimination
     seed = 0;
-    constexpr bool Qt6DeterministicHash = true;
-#else
-    constexpr bool Qt6DeterministicHash = QT_VERSION_MAJOR == 6;
 #endif
 
     auto data = reinterpret_cast<const uchar *>(key.data());
     size_t size = key.size();
 
-    if (seed == 0 && Qt6DeterministicHash) {
-        // fall back to what we used to use prior to Qt 6.8
-        return qHashBits(data, size, seed);
-    }
-
-    // mix in the length as a secondary seed. For seed == 0, seed2 must be
-    // size, to match what we used to do prior to Qt 6.2.
+    // Mix in the length as a secondary seed.
     // Multiplied by 2 to match the byte size of the equiavlent UTF-16 string.
     size_t seed2 = size * 2;
     if (seed)
diff --git a/src/corelib/tools/qhashfunctions.h b/src/corelib/tools/qhashfunctions.h
index 9056d24102..90a269deaa 100644
--- a/src/corelib/tools/qhashfunctions.h
+++ b/src/corelib/tools/qhashfunctions.h
@@ -58,6 +58,12 @@ template <> struct QHashHeterogeneousSearch<QString, QStringView> : std::true_ty
 template <> struct QHashHeterogeneousSearch<QStringView, QString> : std::true_type {};
 template <> struct QHashHeterogeneousSearch<QByteArray, QByteArrayView> : std::true_type {};
 template <> struct QHashHeterogeneousSearch<QByteArrayView, QByteArray> : std::true_type {};
+#ifndef Q_PROCESSOR_ARM
+template <> struct QHashHeterogeneousSearch<QString, QLatin1StringView> : std::true_type {};
+template <> struct QHashHeterogeneousSearch<QStringView, QLatin1StringView> : std::true_type {};
+template <> struct QHashHeterogeneousSearch<QLatin1StringView, QString> : std::true_type {};
+template <> struct QHashHeterogeneousSearch<QLatin1StringView, QStringView> : std::true_type {};
+#endif
 
 namespace QHashPrivate {
 
diff --git a/tests/auto/corelib/tools/qhashfunctions/tst_qhashfunctions.cpp b/tests/auto/corelib/tools/qhashfunctions/tst_qhashfunctions.cpp
index 06f18dfe9c..00ee5763ed 100644
--- a/tests/auto/corelib/tools/qhashfunctions/tst_qhashfunctions.cpp
+++ b/tests/auto/corelib/tools/qhashfunctions/tst_qhashfunctions.cpp
@@ -324,7 +324,7 @@ void tst_QHashFunctions::stringConsistency()
     QCOMPARE(qHash(sv, seed), qHash(value, seed));
     QCOMPARE(qHash(u8bav, seed), qHash(u8ba, seed));
 
-    if (seed || QT_VERSION_MAJOR > 6) {
+    if (seed == 0 || QHashHeterogeneousSearch<QString, QLatin1StringView>::value) {
         QByteArray l1ba = value.toLatin1();
         QLatin1StringView l1sv(l1ba.data(), l1ba.size());
 #ifdef Q_PROCESSOR_ARM