diff --git a/modules/juce_core/native/juce_posix_SharedCode.h b/modules/juce_core/native/juce_posix_SharedCode.h
index 74d1f0304a..e45abb2569 100644
--- a/modules/juce_core/native/juce_posix_SharedCode.h
+++ b/modules/juce_core/native/juce_posix_SharedCode.h
@@ -957,8 +957,8 @@ void Thread::setCurrentThreadAffinityMask (const uint32 affinityMask)
 bool DynamicLibrary::open (const String& name)
 {
     close();
-    handle = dlopen (name.toUTF8(), RTLD_LOCAL | RTLD_NOW);
-    return handle != 0;
+    handle = dlopen (name.isEmpty() ? nullptr : name.toUTF8(), RTLD_LOCAL | RTLD_NOW);
+    return handle != nullptr;
 }
 
 void DynamicLibrary::close()
diff --git a/modules/juce_graphics/geometry/juce_Line.h b/modules/juce_graphics/geometry/juce_Line.h
index f2292e7f9c..e479aec34b 100644
--- a/modules/juce_graphics/geometry/juce_Line.h
+++ b/modules/juce_graphics/geometry/juce_Line.h
@@ -66,8 +66,8 @@ public:
     }
 
     /** Creates a line from its start and end points. */
-    Line (const Point<ValueType>& startPoint,
-          const Point<ValueType>& endPoint) noexcept
+    Line (const Point<ValueType> startPoint,
+          const Point<ValueType> endPoint) noexcept
         : start (startPoint),
           end (endPoint)
     {
@@ -98,10 +98,10 @@ public:
     inline ValueType getEndY() const noexcept                               { return end.y; }
 
     /** Returns the line's start point. */
-    inline const Point<ValueType>& getStart() const noexcept                { return start; }
+    inline Point<ValueType> getStart() const noexcept                       { return start; }
 
     /** Returns the line's end point. */
-    inline const Point<ValueType>& getEnd() const noexcept                  { return end; }
+    inline Point<ValueType> getEnd() const noexcept                         { return end; }
 
     /** Changes this line's start point */
     void setStart (ValueType newStartX, ValueType newStartY) noexcept       { start.setXY (newStartX, newStartY); }
@@ -110,10 +110,10 @@ public:
     void setEnd (ValueType newEndX, ValueType newEndY) noexcept             { end.setXY (newEndX, newEndY); }
 
     /** Changes this line's start point */
-    void setStart (const Point<ValueType>& newStart) noexcept               { start = newStart; }
+    void setStart (const Point<ValueType> newStart) noexcept                { start = newStart; }
 
     /** Changes this line's end point */
-    void setEnd (const Point<ValueType>& newEnd) noexcept                   { end = newEnd; }
+    void setEnd (const Point<ValueType> newEnd) noexcept                    { end = newEnd; }
 
     /** Returns a line that is the same as this one, but with the start and end reversed, */
     const Line reversed() const noexcept                                    { return Line (end, start); }
@@ -250,7 +250,7 @@ public:
         @returns the point's distance from the line
         @see getPositionAlongLineOfNearestPoint
     */
-    ValueType getDistanceFromPoint (const Point<ValueType>& targetPoint,
+    ValueType getDistanceFromPoint (const Point<ValueType> targetPoint,
                                     Point<ValueType>& pointOnLine) const noexcept
     {
         const Point<ValueType> delta (end - start);
@@ -291,7 +291,7 @@ public:
                     turn this number into a position, use getPointAlongLineProportionally().
         @see getDistanceFromPoint, getPointAlongLineProportionally
     */
-    ValueType findNearestProportionalPositionTo (const Point<ValueType>& point) const noexcept
+    ValueType findNearestProportionalPositionTo (const Point<ValueType> point) const noexcept
     {
         const Point<ValueType> delta (end - start);
         const double length = delta.x * delta.x + delta.y * delta.y;
@@ -305,7 +305,7 @@ public:
     /** Finds the point on this line which is nearest to a given point.
         @see getDistanceFromPoint, findNearestProportionalPositionTo
     */
-    Point<ValueType> findNearestPointTo (const Point<ValueType>& point) const noexcept
+    Point<ValueType> findNearestPointTo (const Point<ValueType> point) const noexcept
     {
         return getPointAlongLineProportionally (findNearestProportionalPositionTo (point));
     }
@@ -316,7 +316,7 @@ public:
         coordinate of this line at the given x (assuming the line extends infinitely
         in both directions).
     */
-    bool isPointAbove (const Point<ValueType>& point) const noexcept
+    bool isPointAbove (const Point<ValueType> point) const noexcept
     {
         return start.x != end.x
                 && point.y < ((end.y - start.y)
@@ -349,8 +349,8 @@ private:
     //==============================================================================
     Point<ValueType> start, end;
 
-    static bool findIntersection (const Point<ValueType>& p1, const Point<ValueType>& p2,
-                                  const Point<ValueType>& p3, const Point<ValueType>& p4,
+    static bool findIntersection (const Point<ValueType> p1, const Point<ValueType> p2,
+                                  const Point<ValueType> p3, const Point<ValueType> p4,
                                   Point<ValueType>& intersection) noexcept
     {
         if (p2 == p3)
diff --git a/modules/juce_graphics/geometry/juce_Rectangle.h b/modules/juce_graphics/geometry/juce_Rectangle.h
index efd1df91e0..38f69f1d43 100644
--- a/modules/juce_graphics/geometry/juce_Rectangle.h
+++ b/modules/juce_graphics/geometry/juce_Rectangle.h
@@ -70,7 +70,7 @@ public:
     }
 
     /** Creates a Rectangle from the positions of two opposite corners. */
-    Rectangle (const Point<ValueType>& corner1, const Point<ValueType>& corner2) noexcept
+    Rectangle (const Point<ValueType> corner1, const Point<ValueType> corner2) noexcept
       : pos (jmin (corner1.x, corner2.x),
              jmin (corner1.y, corner2.y)),
         w (corner1.x - corner2.x),
@@ -139,16 +139,16 @@ public:
 
     //==============================================================================
     /** Returns the rectangle's top-left position as a Point. */
-    inline const Point<ValueType>& getPosition() const noexcept                                     { return pos; }
+    inline Point<ValueType> getPosition() const noexcept                                            { return pos; }
 
     /** Changes the position of the rectangle's top-left corner (leaving its size unchanged). */
-    inline void setPosition (const Point<ValueType>& newPos) noexcept                               { pos = newPos; }
+    inline void setPosition (const Point<ValueType> newPos) noexcept                                { pos = newPos; }
 
     /** Changes the position of the rectangle's top-left corner (leaving its size unchanged). */
     inline void setPosition (const ValueType newX, const ValueType newY) noexcept                   { pos.setXY (newX, newY); }
 
     /** Returns the rectangle's top-left position as a Point. */
-    const Point<ValueType>& getTopLeft() const noexcept                                             { return pos; }
+    Point<ValueType> getTopLeft() const noexcept                                                    { return pos; }
 
     /** Returns the rectangle's top-right position as a Point. */
     Point<ValueType> getTopRight() const noexcept                                                   { return Point<ValueType> (pos.x + w, pos.y); }
@@ -188,7 +188,7 @@ public:
     Rectangle withPosition (const ValueType newX, const ValueType newY) const noexcept   { return Rectangle (newX, newY, w, h); }
 
     /** Returns a rectangle with the same size as this one, but a new position. */
-    Rectangle withPosition (const Point<ValueType>& newPos) const noexcept  { return Rectangle (newPos.x, newPos.y, w, h); }
+    Rectangle withPosition (const Point<ValueType> newPos) const noexcept   { return Rectangle (newPos.x, newPos.y, w, h); }
 
     /** Returns a rectangle whose size is the same as this one, but whose top-left position is (0, 0). */
     Rectangle withZeroOrigin() const noexcept                               { return Rectangle (w, h); }
@@ -267,26 +267,26 @@ public:
     }
 
     /** Returns a rectangle which is the same as this one moved by a given amount. */
-    Rectangle operator+ (const Point<ValueType>& deltaPosition) const noexcept
+    Rectangle operator+ (const Point<ValueType> deltaPosition) const noexcept
     {
         return Rectangle (pos.x + deltaPosition.x, pos.y + deltaPosition.y, w, h);
     }
 
     /** Moves this rectangle by a given amount. */
-    Rectangle& operator+= (const Point<ValueType>& deltaPosition) noexcept
+    Rectangle& operator+= (const Point<ValueType> deltaPosition) noexcept
     {
         pos += deltaPosition;
         return *this;
     }
 
     /** Returns a rectangle which is the same as this one moved by a given amount. */
-    Rectangle operator- (const Point<ValueType>& deltaPosition) const noexcept
+    Rectangle operator- (const Point<ValueType> deltaPosition) const noexcept
     {
         return Rectangle (pos.x - deltaPosition.x, pos.y - deltaPosition.y, w, h);
     }
 
     /** Moves this rectangle by a given amount. */
-    Rectangle& operator-= (const Point<ValueType>& deltaPosition) noexcept
+    Rectangle& operator-= (const Point<ValueType> deltaPosition) noexcept
     {
         pos -= deltaPosition;
         return *this;
@@ -459,7 +459,7 @@ public:
     }
 
     /** Returns true if this co-ordinate is inside the rectangle. */
-    bool contains (const Point<ValueType>& point) const noexcept
+    bool contains (const Point<ValueType> point) const noexcept
     {
         return point.x >= pos.x && point.y >= pos.y && point.x < pos.x + w && point.y < pos.y + h;
     }
@@ -472,7 +472,7 @@ public:
     }
 
     /** Returns the nearest point to the specified point that lies within this rectangle. */
-    Point<ValueType> getConstrainedPoint (const Point<ValueType>& point) const noexcept
+    Point<ValueType> getConstrainedPoint (const Point<ValueType> point) const noexcept
     {
         return Point<ValueType> (jlimit (pos.x, pos.x + w, point.x),
                                  jlimit (pos.y, pos.y + h, point.y));