FilterKey: fix ambiguous relational operators in C++20

The member operators weren't const, leading them to be ambiguous with
their reversed versions.

Fix by adding a private equals() function (to avoid churning the
implementation) and making the relational operators hidden friends.

Task-number: QTBUG-104172
Change-Id: I97e74ef26fc2712d6f97c8f7d7bd61d6a625b42e
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>
(cherry picked from commit bcd20a74c9f2cd5920ecc5c1c0bb6d577db6cb50)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 8 insertions, 8 deletions

diff --git a/src/render/materialsystem/filterkey.cpp b/src/render/materialsystem/filterkey.cpp
index 778a9ee75..572d11e57 100644
--- a/src/render/materialsystem/filterkey.cpp
+++ b/src/render/materialsystem/filterkey.cpp
@@ -83,7 +83,7 @@ void FilterKey::syncFromFrontEnd(const QNode *frontEnd, bool firstTime)
     }
 }
 
-bool FilterKey::operator ==(const FilterKey &other)
+bool FilterKey::equals(const FilterKey &other) const
 {
     if (&other == this)
         return true;
@@ -101,11 +101,6 @@ bool FilterKey::operator ==(const FilterKey &other)
             other.value() == value());
 }
 
-bool FilterKey::operator !=(const FilterKey &other)
-{
-    return !operator ==(other);
-}
-
 } // namespace Render
 } // namespace Qt3DRender
 
diff --git a/src/render/materialsystem/filterkey_p.h b/src/render/materialsystem/filterkey_p.h
index 91d0ba1f0..1fe6bba7b 100644
--- a/src/render/materialsystem/filterkey_p.h
+++ b/src/render/materialsystem/filterkey_p.h
@@ -72,10 +72,15 @@ public:
     const QVariant &value() const { return m_value; }
     const QString &name() const { return m_name; }
     void syncFromFrontEnd(const Qt3DCore::QNode *frontEnd, bool firstTime) override;
-    bool operator ==(const FilterKey &other);
-    bool operator !=(const FilterKey &other);
+
+    friend bool operator==(const FilterKey &lhs, const FilterKey &rhs)
+    { return lhs.equals(rhs); }
+    friend bool operator !=(const FilterKey &lhs, const FilterKey &rhs)
+    { return !lhs.equals(rhs); }
 
 private:
+    bool equals(const FilterKey &other) const;
+
     QVariant m_value;
     QString m_name;
 };