Constrain the comparison operators for our container classes

This had already been in very few places, where we ran into issues with
this before. More generic constraints here will significantly reduce the
amount of error messages a user has to parse in case he tries to instantiate
an operator by accident (or with a lacking comparison operator for one of
it's template arguments).

Change-Id: I1521d19c55d99732d9742402bd534c390a8e4242
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 19 insertions, 18 deletions

diff --git a/src/corelib/tools/qcontiguouscache.h b/src/corelib/tools/qcontiguouscache.h
index 81361f219a..79f5e3fdb6 100644
--- a/src/corelib/tools/qcontiguouscache.h
+++ b/src/corelib/tools/qcontiguouscache.h
@@ -97,8 +97,25 @@ public:
     inline QContiguousCache<T> &operator=(QContiguousCache<T> &&other) noexcept
     { qSwap(d, other.d); return *this; }
     inline void swap(QContiguousCache<T> &other) noexcept { qSwap(d, other.d); }
-    bool operator==(const QContiguousCache<T> &other) const;
-    inline bool operator!=(const QContiguousCache<T> &other) const { return !(*this == other); }
+
+    template <typename U = T>
+    QTypeTraits::compare_eq_result<U> operator==(const QContiguousCache<T> &other) const
+    {
+        if (other.d == d)
+            return true;
+        if (other.d->start != d->start
+                || other.d->count != d->count
+                || other.d->offset != d->offset
+                || other.d->alloc != d->alloc)
+            return false;
+        for (qsizetype i = firstIndex(); i <= lastIndex(); ++i)
+            if (!(at(i) == other.at(i)))
+                return false;
+        return true;
+    }
+    template <typename U = T>
+    QTypeTraits::compare_eq_result<U> operator!=(const QContiguousCache<T> &other) const
+    { return !(*this == other); }
 
     inline qsizetype capacity() const {return d->alloc; }
     inline qsizetype count() const { return d->count; }
@@ -272,22 +289,6 @@ QContiguousCache<T> &QContiguousCache<T>::operator=(const QContiguousCache<T> &o
 }
 
 template <typename T>
-bool QContiguousCache<T>::operator==(const QContiguousCache<T> &other) const
-{
-    if (other.d == d)
-        return true;
-    if (other.d->start != d->start
-            || other.d->count != d->count
-            || other.d->offset != d->offset
-            || other.d->alloc != d->alloc)
-        return false;
-    for (qsizetype i = firstIndex(); i <= lastIndex(); ++i)
-        if (!(at(i) == other.at(i)))
-            return false;
-    return true;
-}
-
-template <typename T>
 void QContiguousCache<T>::freeData(Data *x)
 {
     if (QTypeInfo<T>::isComplex) {