Provide qHash for all C++ fundamental types

Except for (void and) bool, which we may not want to have
to avoid accidental implicit conversions.
Drive-by, rearrange qHash overloads to C++ types first,
and then Qt ones.

Change-Id: I9c4ecef5f28568d35ca52e339583851ce53b3bae
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

2 files changed, 56 insertions, 9 deletions

diff --git a/src/corelib/tools/qhash.cpp b/src/corelib/tools/qhash.cpp
index 97dda58748..bf5031523d 100644
--- a/src/corelib/tools/qhash.cpp
+++ b/src/corelib/tools/qhash.cpp
@@ -769,6 +769,34 @@ uint qt_hash(QStringView key, uint chained) noexcept
     Returns the hash value for the \a key, using \a seed to seed the calculation.
 */
 
+/*! \fn size_t qHash(char8_t key, size_t seed = 0)
+    \relates QHash
+    \since 6.0
+
+    Returns the hash value for the \a key, using \a seed to seed the calculation.
+*/
+
+/*! \fn size_t qHash(char16_t key, size_t seed = 0)
+    \relates QHash
+    \since 6.0
+
+    Returns the hash value for the \a key, using \a seed to seed the calculation.
+*/
+
+/*! \fn size_t qHash(char32_t key, size_t seed = 0)
+    \relates QHash
+    \since 6.0
+
+    Returns the hash value for the \a key, using \a seed to seed the calculation.
+*/
+
+/*! \fn size_t qHash(wchar_t key, size_t seed = 0)
+    \relates QHash
+    \since 6.0
+
+    Returns the hash value for the \a key, using \a seed to seed the calculation.
+*/
+
 /*! \fn size_t qHash(float key, size_t seed) noexcept
     \relates QHash
     \since 5.3
@@ -870,6 +898,13 @@ size_t qHash(long double key, size_t seed) noexcept
     Returns the hash value for the \a key, using \a seed to seed the calculation.
 */
 
+/*! \fn template <class T> size_t qHash(std::nullptr_t key, size_t seed = 0)
+    \relates QHash
+    \since 6.0
+
+    Returns the hash value for the \a key, using \a seed to seed the calculation.
+*/
+
 /*!
     \class QHash
     \inmodule QtCore
diff --git a/src/corelib/tools/qhashfunctions.h b/src/corelib/tools/qhashfunctions.h
index e52688b88d..aaa7758758 100644
--- a/src/corelib/tools/qhashfunctions.h
+++ b/src/corelib/tools/qhashfunctions.h
@@ -95,6 +95,7 @@ Q_DECL_CONST_FUNCTION constexpr size_t hash(size_t key, size_t seed) noexcept
 
 Q_CORE_EXPORT Q_DECL_PURE_FUNCTION size_t qHashBits(const void *p, size_t size, size_t seed = 0) noexcept;
 
+// C++ builtin types
 Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline size_t qHash(char key, size_t seed = 0) noexcept
 { return QHashPrivate::hash(size_t(key), seed); }
 Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline size_t qHash(uchar key, size_t seed = 0) noexcept
@@ -132,6 +133,26 @@ Q_CORE_EXPORT Q_DECL_CONST_FUNCTION size_t qHash(double key, size_t seed = 0) no
 #if !defined(Q_OS_DARWIN) || defined(Q_CLANG_QDOC)
 Q_CORE_EXPORT Q_DECL_CONST_FUNCTION size_t qHash(long double key, size_t seed = 0) noexcept;
 #endif
+Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline size_t qHash(wchar_t key, size_t seed = 0) noexcept
+{ return QHashPrivate::hash(size_t(key), seed); }
+Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline size_t qHash(char16_t key, size_t seed = 0) noexcept
+{ return QHashPrivate::hash(size_t(key), seed); }
+Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline size_t qHash(char32_t key, size_t seed = 0) noexcept
+{ return QHashPrivate::hash(size_t(key), seed); }
+#ifdef __cpp_char8_t
+Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline size_t qHash(char8_t key, size_t seed = 0) noexcept
+{ return QHashPrivate::hash(size_t(key), seed); }
+#endif
+template <class T> inline size_t qHash(const T *key, size_t seed = 0) noexcept
+{
+    return qHash(reinterpret_cast<quintptr>(key), seed);
+}
+Q_DECL_CONST_FUNCTION constexpr inline size_t qHash(std::nullptr_t, size_t seed = 0) noexcept
+{
+    return seed;
+}
+
+// (some) Qt types
 Q_DECL_CONST_FUNCTION constexpr inline size_t qHash(const QChar key, size_t seed = 0) noexcept { return qHash(key.unicode(), seed); }
 Q_CORE_EXPORT Q_DECL_PURE_FUNCTION size_t qHash(const QByteArray &key, size_t seed = 0) noexcept;
 #if QT_STRINGVIEW_LEVEL < 2
@@ -143,15 +164,6 @@ Q_CORE_EXPORT Q_DECL_PURE_FUNCTION size_t qHash(const QBitArray &key, size_t see
 Q_CORE_EXPORT Q_DECL_PURE_FUNCTION size_t qHash(QLatin1String key, size_t seed = 0) noexcept;
 Q_CORE_EXPORT Q_DECL_PURE_FUNCTION uint qt_hash(QStringView key, uint chained = 0) noexcept;
 
-Q_DECL_CONST_FUNCTION constexpr inline size_t qHash(std::nullptr_t, size_t seed = 0) noexcept
-{
-    return seed;
-}
-
-template <class T> inline size_t qHash(const T *key, size_t seed = 0) noexcept
-{
-    return qHash(reinterpret_cast<quintptr>(key), seed);
-}
 template<typename T> inline size_t qHash(const T &t, size_t seed)
     noexcept(noexcept(qHash(t)))
 { return qHash(t) ^ seed; }