qBound: add an assert on !(upper < lower)

It's a precondition and we might just as well check it, given that
people have actually got the order of the arguments wrong (cf.
QTBUG-69330).

Unfortunately, Q_ASSERT is defined below qBound in qglobal.h, so I had
to reshuffle some code around.

Change-Id: I82e52bcb863ff8c96594817e0cd5d7d2abe2e57e
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 67 insertions, 53 deletions

diff --git a/src/corelib/global/qglobal.h b/src/corelib/global/qglobal.h
index 1a3f3d6482..25002efdca 100644
--- a/src/corelib/global/qglobal.h
+++ b/src/corelib/global/qglobal.h
@@ -809,59 +809,6 @@ constexpr inline qint64 qRound64(float d)
 { return d >= 0.0f ? qint64(d + 0.5f) : qint64(d - 0.5f); }
 #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)
-{ 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)
-{ 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)
-{ 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)
-{ return qMax(min, qMin(max, val)); }
-
 #ifndef Q_FORWARD_DECLARE_OBJC_CLASS
 #  ifdef __OBJC__
 #    define Q_FORWARD_DECLARE_OBJC_CLASS(classname) @class classname
@@ -1084,6 +1031,73 @@ 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));
+}
+
 [[nodiscard]] constexpr bool qFuzzyCompare(double p1, double p2)
 {
     return (qAbs(p1 - p2) * 1000000000000. <= qMin(qAbs(p1), qAbs(p2)));