Move qMin/qMax/qBound() to a separate qminmax.h header

Also replaced qMin() uses in qnumeric.h with QtPrivate::min().
Including qassert.h in qminmax.h leads to indirect include of qglobal.h
(through qcompilerdetection.h), which in turn leads to qMin() declaration
not being available at the point the compiler sees qFuzzyCompare()
definitions in qnumeric.h. This makes the headersclean build fail.

Task-number: QTBUG-99313
Change-Id: I824422698b06f94a4a62e2f19d4507c87f90334e
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

6 files changed, 137 insertions, 106 deletions

diff --git a/src/corelib/CMakeLists.txt b/src/corelib/CMakeLists.txt
index 575bb1b0f4..5f8fc1c313 100644
--- a/src/corelib/CMakeLists.txt
+++ b/src/corelib/CMakeLists.txt
@@ -64,6 +64,7 @@ qt_internal_add_module(Core
         global/qlibraryinfo.cpp global/qlibraryinfo.h global/qlibraryinfo_p.h
         global/qlogging.cpp global/qlogging.h global/qlogging_p.h
         global/qmalloc.cpp
+        global/qminmax.h
         global/qnamespace.h # this header is specified on purpose so AUTOMOC processes it
         global/qnativeinterface.h global/qnativeinterface_p.h
         global/qnumeric.cpp global/qnumeric.h global/qnumeric_p.h
diff --git a/src/corelib/global/qglobal.cpp b/src/corelib/global/qglobal.cpp
index d8d618e92b..9805195d76 100644
--- a/src/corelib/global/qglobal.cpp
+++ b/src/corelib/global/qglobal.cpp
@@ -861,43 +861,6 @@ using namespace Qt::StringLiterals;
     \snippet code/src_corelib_global_qglobal.cpp 12B
 */
 
-/*! \fn template <typename T> const T &qMin(const T &a, const T &b)
-    \relates <QtGlobal>
-
-    Returns the minimum of \a a and \a b.
-
-    Example:
-
-    \snippet code/src_corelib_global_qglobal.cpp 13
-
-    \sa qMax(), qBound()
-*/
-
-/*! \fn template <typename T> const T &qMax(const T &a, const T &b)
-    \relates <QtGlobal>
-
-    Returns the maximum of \a a and \a b.
-
-    Example:
-
-    \snippet code/src_corelib_global_qglobal.cpp 14
-
-    \sa qMin(), qBound()
-*/
-
-/*! \fn template <typename T> const T &qBound(const T &min, const T &val, const T &max)
-    \relates <QtGlobal>
-
-    Returns \a val bounded by \a min and \a max. This is equivalent
-    to qMax(\a min, qMin(\a val, \a max)).
-
-    Example:
-
-    \snippet code/src_corelib_global_qglobal.cpp 15
-
-    \sa qMin(), qMax()
-*/
-
 /*!
     \macro QT_VERSION_STR
     \relates <QtGlobal>
diff --git a/src/corelib/global/qglobal.h b/src/corelib/global/qglobal.h
index 82c6e5e037..54ce2ff6fa 100644
--- a/src/corelib/global/qglobal.h
+++ b/src/corelib/global/qglobal.h
@@ -446,73 +446,6 @@ typedef void (*QFunctionPointer)();
 #  define Q_UNIMPLEMENTED() qWarning("Unimplemented code.")
 #endif
 
-namespace QTypeTraits {
-
-namespace detail {
-template<typename T, typename U,
-         typename = std::enable_if_t<std::is_arithmetic_v<T> && std::is_arithmetic_v<U> &&
-                                     std::is_floating_point_v<T> == std::is_floating_point_v<U> &&
-                                     std::is_signed_v<T> == std::is_signed_v<U> &&
-                                     !std::is_same_v<T, bool> && !std::is_same_v<U, bool> &&
-                                     !std::is_same_v<T, char> && !std::is_same_v<U, char>>>
-struct Promoted
-{
-    using type = decltype(T() + U());
-};
-}
-
-template <typename T, typename U>
-using Promoted = typename detail::Promoted<T, U>::type;
-
-}
-
-template <typename T>
-constexpr inline const T &qMin(const T &a, const T &b) { return (a < b) ? a : b; }
-template <typename T>
-constexpr inline const T &qMax(const T &a, const T &b) { return (a < b) ? b : a; }
-template <typename T>
-constexpr inline const T &qBound(const T &min, const T &val, const T &max)
-{
-    Q_ASSERT(!(max < min));
-    return qMax(min, qMin(max, val));
-}
-template <typename T, typename U>
-constexpr inline QTypeTraits::Promoted<T, U> qMin(const T &a, const U &b)
-{
-    using P = QTypeTraits::Promoted<T, U>;
-    P _a = a;
-    P _b = b;
-    return (_a < _b) ? _a : _b;
-}
-template <typename T, typename U>
-constexpr inline QTypeTraits::Promoted<T, U> qMax(const T &a, const U &b)
-{
-    using P = QTypeTraits::Promoted<T, U>;
-    P _a = a;
-    P _b = b;
-    return (_a < _b) ? _b : _a;
-}
-template <typename T, typename U>
-constexpr inline QTypeTraits::Promoted<T, U> qBound(const T &min, const U &val, const T &max)
-{
-    Q_ASSERT(!(max < min));
-    return qMax(min, qMin(max, val));
-}
-template <typename T, typename U>
-constexpr inline QTypeTraits::Promoted<T, U> qBound(const T &min, const T &val, const U &max)
-{
-    using P = QTypeTraits::Promoted<T, U>;
-    Q_ASSERT(!(P(max) < P(min)));
-    return qMax(min, qMin(max, val));
-}
-template <typename T, typename U>
-constexpr inline QTypeTraits::Promoted<T, U> qBound(const U &min, const T &val, const T &max)
-{
-    using P = QTypeTraits::Promoted<T, U>;
-    Q_ASSERT(!(P(max) < P(min)));
-    return qMax(min, qMin(max, val));
-}
-
 /*
    Compilers which follow outdated template instantiation rules
    require a class to have a comparison operator to exist when
@@ -704,6 +637,7 @@ QT_END_NAMESPACE
 #include <QtCore/qenvironmentvariables.h>
 #include <QtCore/qforeach.h>
 #include <QtCore/qglobalstatic.h>
+#include <QtCore/qminmax.h>
 #include <QtCore/qnumeric.h>
 #include <QtCore/qoverload.h>
 #include <QtCore/qtdeprecationmarkers.h>
diff --git a/src/corelib/global/qminmax.h b/src/corelib/global/qminmax.h
new file mode 100644
index 0000000000..e6fb62bf9d
--- /dev/null
+++ b/src/corelib/global/qminmax.h
@@ -0,0 +1,88 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#ifndef QMINMAX_H
+#define QMINMAX_H
+
+#if 0
+#pragma qt_class(QtMinMax)
+#pragma qt_sync_stop_processing
+#endif
+
+#include <QtCore/qassert.h>
+#include <QtCore/qtconfigmacros.h>
+
+#include <type_traits>
+
+QT_BEGIN_NAMESPACE
+
+namespace QTypeTraits {
+
+namespace detail {
+template<typename T, typename U,
+         typename = std::enable_if_t<std::is_arithmetic_v<T> && std::is_arithmetic_v<U> &&
+                                     std::is_floating_point_v<T> == std::is_floating_point_v<U> &&
+                                     std::is_signed_v<T> == std::is_signed_v<U> &&
+                                     !std::is_same_v<T, bool> && !std::is_same_v<U, bool> &&
+                                     !std::is_same_v<T, char> && !std::is_same_v<U, char>>>
+struct Promoted
+{
+    using type = decltype(T() + U());
+};
+}
+
+template <typename T, typename U>
+using Promoted = typename detail::Promoted<T, U>::type;
+
+}
+
+template <typename T>
+constexpr inline const T &qMin(const T &a, const T &b) { return (a < b) ? a : b; }
+template <typename T>
+constexpr inline const T &qMax(const T &a, const T &b) { return (a < b) ? b : a; }
+template <typename T>
+constexpr inline const T &qBound(const T &min, const T &val, const T &max)
+{
+    Q_ASSERT(!(max < min));
+    return qMax(min, qMin(max, val));
+}
+template <typename T, typename U>
+constexpr inline QTypeTraits::Promoted<T, U> qMin(const T &a, const U &b)
+{
+    using P = QTypeTraits::Promoted<T, U>;
+    P _a = a;
+    P _b = b;
+    return (_a < _b) ? _a : _b;
+}
+template <typename T, typename U>
+constexpr inline QTypeTraits::Promoted<T, U> qMax(const T &a, const U &b)
+{
+    using P = QTypeTraits::Promoted<T, U>;
+    P _a = a;
+    P _b = b;
+    return (_a < _b) ? _b : _a;
+}
+template <typename T, typename U>
+constexpr inline QTypeTraits::Promoted<T, U> qBound(const T &min, const U &val, const T &max)
+{
+    Q_ASSERT(!(max < min));
+    return qMax(min, qMin(max, val));
+}
+template <typename T, typename U>
+constexpr inline QTypeTraits::Promoted<T, U> qBound(const T &min, const T &val, const U &max)
+{
+    using P = QTypeTraits::Promoted<T, U>;
+    Q_ASSERT(!(P(max) < P(min)));
+    return qMax(min, qMin(max, val));
+}
+template <typename T, typename U>
+constexpr inline QTypeTraits::Promoted<T, U> qBound(const U &min, const T &val, const T &max)
+{
+    using P = QTypeTraits::Promoted<T, U>;
+    Q_ASSERT(!(P(max) < P(min)));
+    return qMax(min, qMin(max, val));
+}
+
+QT_END_NAMESPACE
+
+#endif // QMINMAX_H
diff --git a/src/corelib/global/qminmax.qdoc b/src/corelib/global/qminmax.qdoc
new file mode 100644
index 0000000000..36f680b4c7
--- /dev/null
+++ b/src/corelib/global/qminmax.qdoc
@@ -0,0 +1,39 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
+
+/*! \fn template <typename T> const T &qMin(const T &a, const T &b)
+    \relates <QtMinMax>
+
+    Returns the minimum of \a a and \a b.
+
+    Example:
+
+    \snippet code/src_corelib_global_qglobal.cpp 13
+
+    \sa qMax(), qBound()
+*/
+
+/*! \fn template <typename T> const T &qMax(const T &a, const T &b)
+    \relates <QtMinMax>
+
+    Returns the maximum of \a a and \a b.
+
+    Example:
+
+    \snippet code/src_corelib_global_qglobal.cpp 14
+
+    \sa qMin(), qBound()
+*/
+
+/*! \fn template <typename T> const T &qBound(const T &min, const T &val, const T &max)
+    \relates <QtMinMax>
+
+    Returns \a val bounded by \a min and \a max. This is equivalent
+    to qMax(\a min, qMin(\a val, \a max)).
+
+    Example:
+
+    \snippet code/src_corelib_global_qglobal.cpp 15
+
+    \sa qMin(), qMax()
+*/
diff --git a/src/corelib/global/qnumeric.h b/src/corelib/global/qnumeric.h
index 24fa782f06..9ecbbc712a 100644
--- a/src/corelib/global/qnumeric.h
+++ b/src/corelib/global/qnumeric.h
@@ -9,6 +9,7 @@
 #endif
 
 #include <QtCore/qglobal.h>
+
 #include <cmath>
 #include <limits>
 #include <type_traits>
@@ -356,14 +357,19 @@ constexpr inline qint64 qRound64(float d)
 { return d >= 0.0f ? qint64(d + 0.5f) : qint64(d - 0.5f); }
 #endif
 
+namespace QtPrivate {
+template <typename T>
+constexpr inline const T &min(const T &a, const T &b) { return (a < b) ? a : b; }
+}
+
 [[nodiscard]] constexpr bool qFuzzyCompare(double p1, double p2)
 {
-    return (qAbs(p1 - p2) * 1000000000000. <= qMin(qAbs(p1), qAbs(p2)));
+    return (qAbs(p1 - p2) * 1000000000000. <= QtPrivate::min(qAbs(p1), qAbs(p2)));
 }
 
 [[nodiscard]] constexpr bool qFuzzyCompare(float p1, float p2)
 {
-    return (qAbs(p1 - p2) * 100000.f <= qMin(qAbs(p1), qAbs(p2)));
+    return (qAbs(p1 - p2) * 100000.f <= QtPrivate::min(qAbs(p1), qAbs(p2)));
 }
 
 [[nodiscard]] constexpr bool qFuzzyIsNull(double d)