diff --git a/python/core/geometry/qgsabstractgeometry.sip b/python/core/geometry/qgsabstractgeometry.sip
index 0289ac3e70a9..9a9f69365270 100644
--- a/python/core/geometry/qgsabstractgeometry.sip
+++ b/python/core/geometry/qgsabstractgeometry.sip
@@ -646,6 +646,9 @@ class QgsVertexIterator
 %End
   public:
     QgsVertexIterator();
+%Docstring
+Constructor for QgsVertexIterator
+%End
 
     QgsVertexIterator( const QgsAbstractGeometry *geometry );
 %Docstring
diff --git a/src/3d/chunks/qgschunklist_p.cpp b/src/3d/chunks/qgschunklist_p.cpp
index f7f8508b0453..e38534fdd59e 100644
--- a/src/3d/chunks/qgschunklist_p.cpp
+++ b/src/3d/chunks/qgschunklist_p.cpp
@@ -19,13 +19,6 @@
 
 ///@cond PRIVATE
 
-QgsChunkList::QgsChunkList()
-  : mHead( nullptr )
-  , mTail( nullptr )
-  , mCount( 0 )
-{
-}
-
 int QgsChunkList::trueCount() const
 {
   int len = 0;
diff --git a/src/3d/chunks/qgschunklist_p.h b/src/3d/chunks/qgschunklist_p.h
index 70f9454542f3..f3febb72631f 100644
--- a/src/3d/chunks/qgschunklist_p.h
+++ b/src/3d/chunks/qgschunklist_p.h
@@ -64,7 +64,8 @@ struct QgsChunkListEntry
 class QgsChunkList
 {
   public:
-    QgsChunkList();
+    //! Constructor for QgsChunkList
+    QgsChunkList() = default;
 
     //! Counts the real number of entries by walking the list (for debugging purposes only)
     int trueCount() const;
@@ -99,7 +100,7 @@ class QgsChunkList
   private:
     QgsChunkListEntry *mHead = nullptr;
     QgsChunkListEntry *mTail = nullptr;
-    int mCount;
+    int mCount = 0;
 };
 
 /// @endcond
diff --git a/src/3d/qgs3dmapscene.cpp b/src/3d/qgs3dmapscene.cpp
index b76d8dfe8059..0af795f80063 100644
--- a/src/3d/qgs3dmapscene.cpp
+++ b/src/3d/qgs3dmapscene.cpp
@@ -42,7 +42,6 @@
 Qgs3DMapScene::Qgs3DMapScene( const Qgs3DMapSettings &map, Qt3DExtras::QForwardRenderer *defaultFrameGraph, Qt3DRender::QRenderSettings *renderSettings, Qt3DRender::QCamera *camera, const QRect &viewportRect, Qt3DCore::QNode *parent )
   : Qt3DCore::QEntity( parent )
   , mMap( map )
-  , mTerrain( nullptr )
   , mForwardRenderer( defaultFrameGraph )
 {
 
diff --git a/src/3d/qgs3dmapsettings.cpp b/src/3d/qgs3dmapsettings.cpp
index 0d102c7e7719..2559a8dcc0f2 100644
--- a/src/3d/qgs3dmapsettings.cpp
+++ b/src/3d/qgs3dmapsettings.cpp
@@ -26,23 +26,6 @@
 #include "qgssymbollayerutils.h"
 #include "qgsrasterlayer.h"
 
-
-Qgs3DMapSettings::Qgs3DMapSettings()
-  : mOriginX( 0 )
-  , mOriginY( 0 )
-  , mOriginZ( 0 )
-  , mBackgroundColor( Qt::black )
-  , mTerrainVerticalScale( 1 )
-  , mMapTileResolution( 512 )
-  , mMaxTerrainScreenError( 3.f )
-  , mMaxTerrainGroundError( 1.f )
-  , mShowTerrainBoundingBoxes( false )
-  , mShowTerrainTileInfo( false )
-  , mShowLabels( false )
-  , mSkyboxEnabled( false )
-{
-}
-
 Qgs3DMapSettings::Qgs3DMapSettings( const Qgs3DMapSettings &other )
   : QObject()
   , mOriginX( other.mOriginX )
diff --git a/src/3d/qgs3dmapsettings.h b/src/3d/qgs3dmapsettings.h
index b522a11242ab..eeefd8d9b877 100644
--- a/src/3d/qgs3dmapsettings.h
+++ b/src/3d/qgs3dmapsettings.h
@@ -47,7 +47,9 @@ class _3D_EXPORT Qgs3DMapSettings : public QObject
 {
     Q_OBJECT
   public:
-    Qgs3DMapSettings();
+
+    //! Constructor for Qgs3DMapSettings
+    Qgs3DMapSettings() = default;
     //! Copy constructor
     Qgs3DMapSettings( const Qgs3DMapSettings &other );
     ~Qgs3DMapSettings();
@@ -206,23 +208,28 @@ class _3D_EXPORT Qgs3DMapSettings : public QObject
     void showLabelsChanged();
 
   private:
-    double mOriginX, mOriginY, mOriginZ;   //!< Coordinates in map CRS at which our 3D world has origin (0,0,0)
+    //! X coordinate in map CRS at which our 3D world has origin (0,0,0)
+    double mOriginX = 0;
+    //! Y coordinate in map CRS at which our 3D world has origin (0,0,0)
+    double mOriginY = 0;
+    //! Z coordinate in map CRS at which our 3D world has origin (0,0,0)
+    double mOriginZ = 0;
     QgsCoordinateReferenceSystem mCrs;   //!< Destination coordinate system of the world
-    QColor mBackgroundColor;   //!< Background color of the scene
-    QColor mSelectionColor;    //!< Color to be used for selected map features
-    double mTerrainVerticalScale;   //!< Multiplier of terrain heights to make the terrain shape more pronounced
+    QColor mBackgroundColor = Qt::black;   //!< Background color of the scene
+    QColor mSelectionColor; //!< Color to be used for selected map features
+    double mTerrainVerticalScale = 1;   //!< Multiplier of terrain heights to make the terrain shape more pronounced
     std::unique_ptr<QgsTerrainGenerator> mTerrainGenerator;  //!< Implementation of the terrain generation
-    int mMapTileResolution;   //!< Size of map textures of tiles in pixels (width/height)
-    float mMaxTerrainScreenError;   //!< Maximum allowed terrain error in pixels (determines when tiles are switched to more detailed ones)
-    float mMaxTerrainGroundError;  //!< Maximum allowed horizontal map error in map units (determines how many zoom levels will be used)
-    bool mShowTerrainBoundingBoxes;  //!< Whether to show bounding boxes of entities - useful for debugging
-    bool mShowTerrainTileInfo;  //!< Whether to draw extra information about terrain tiles to the textures - useful for debugging
-    bool mShowLabels; //!< Whether to display labels on terrain tiles
+    int mMapTileResolution = 512;   //!< Size of map textures of tiles in pixels (width/height)
+    float mMaxTerrainScreenError = 3.f;   //!< Maximum allowed terrain error in pixels (determines when tiles are switched to more detailed ones)
+    float mMaxTerrainGroundError = 1.f;  //!< Maximum allowed horizontal map error in map units (determines how many zoom levels will be used)
+    bool mShowTerrainBoundingBoxes = false;  //!< Whether to show bounding boxes of entities - useful for debugging
+    bool mShowTerrainTileInfo = false;  //!< Whether to draw extra information about terrain tiles to the textures - useful for debugging
+    bool mShowLabels = false; //!< Whether to display labels on terrain tiles
     QList<QgsMapLayerRef> mLayers;   //!< Layers to be rendered
     QList<QgsAbstract3DRenderer *> mRenderers;  //!< Extra stuff to render as 3D object
-    bool mSkyboxEnabled;  //!< Whether to render skybox
-    QString mSkyboxFileBase;   //!< Base part of the files with skybox textures
-    QString mSkyboxFileExtension;  //!< Extension part of the files with skybox textures
+    bool mSkyboxEnabled = false;  //!< Whether to render skybox
+    QString mSkyboxFileBase; //!< Base part of the files with skybox textures
+    QString mSkyboxFileExtension; //!< Extension part of the files with skybox textures
 };
 
 
diff --git a/src/3d/qgsaabb.cpp b/src/3d/qgsaabb.cpp
index 3ac101d50787..2dc9544f2f6b 100644
--- a/src/3d/qgsaabb.cpp
+++ b/src/3d/qgsaabb.cpp
@@ -15,11 +15,6 @@
 
 #include "qgsaabb.h"
 
-QgsAABB::QgsAABB()
-  : xMin( 0 ), yMin( 0 ), zMin( 0 ), xMax( 0 ), yMax( 0 ), zMax( 0 )
-{
-}
-
 QgsAABB::QgsAABB( float xMin, float yMin, float zMin, float xMax, float yMax, float zMax )
   : xMin( xMin ), yMin( yMin ), zMin( zMin ), xMax( xMax ), yMax( yMax ), zMax( zMax )
 {
diff --git a/src/3d/qgsaabb.h b/src/3d/qgsaabb.h
index 84319bebb89e..7b0e7f201d8f 100644
--- a/src/3d/qgsaabb.h
+++ b/src/3d/qgsaabb.h
@@ -31,7 +31,7 @@ class _3D_EXPORT QgsAABB
 {
   public:
     //! Constructs bounding box with null coordinates
-    QgsAABB();
+    QgsAABB() = default;
 
     //! Constructs bounding box
     QgsAABB( float xMin, float yMin, float zMin, float xMax, float yMax, float zMax );
@@ -72,8 +72,12 @@ class _3D_EXPORT QgsAABB
     //! Returns a list of pairs of vertices (useful for display of bounding boxes)
     QList<QVector3D> verticesForLines() const;
 
-    float xMin, yMin, zMin;
-    float xMax, yMax, zMax;
+    float xMin = 0.0f;
+    float yMin = 0.0f;
+    float zMin = 0.0f;
+    float xMax = 0.0f;
+    float yMax = 0.0f;
+    float zMax = 0.0f;
 };
 
 #endif // QGSAABB_H
diff --git a/src/3d/qgscameracontroller.cpp b/src/3d/qgscameracontroller.cpp
index 590bd871003e..2b323bf8802a 100644
--- a/src/3d/qgscameracontroller.cpp
+++ b/src/3d/qgscameracontroller.cpp
@@ -23,7 +23,6 @@
 
 QgsCameraController::QgsCameraController( Qt3DCore::QNode *parent )
   : Qt3DCore::QEntity( parent )
-  , mLastPressedHeight( 0 )
   , mMouseDevice( new Qt3DInput::QMouseDevice() )
   , mKeyboardDevice( new Qt3DInput::QKeyboardDevice() )
   , mMouseHandler( new Qt3DInput::QMouseHandler )
diff --git a/src/3d/qgscameracontroller.h b/src/3d/qgscameracontroller.h
index 1b2c974094d5..6d4aa8ec2481 100644
--- a/src/3d/qgscameracontroller.h
+++ b/src/3d/qgscameracontroller.h
@@ -76,7 +76,7 @@ class _3D_EXPORT QgsCameraController : public Qt3DCore::QEntity
     //! used for computation of translation when dragging mouse
     QRect mViewport;
     //! height of terrain when mouse button was last pressed - for camera control
-    float mLastPressedHeight;
+    float mLastPressedHeight = 0;
 
     struct CameraData
     {
diff --git a/src/3d/qgsphongmaterialsettings.h b/src/3d/qgsphongmaterialsettings.h
index 800d632fcf59..2bfb00ab48db 100644
--- a/src/3d/qgsphongmaterialsettings.h
+++ b/src/3d/qgsphongmaterialsettings.h
@@ -35,7 +35,6 @@ class _3D_EXPORT QgsPhongMaterialSettings
       : mAmbient( QColor::fromRgbF( 0.1f, 0.1f, 0.1f, 1.0f ) )
       , mDiffuse( QColor::fromRgbF( 0.7f, 0.7f, 0.7f, 1.0f ) )
       , mSpecular( QColor::fromRgbF( 1.0f, 1.0f, 1.0f, 1.0f ) )
-      , mShininess( 0.0f )
     {
     }
 
@@ -66,7 +65,7 @@ class _3D_EXPORT QgsPhongMaterialSettings
     QColor mAmbient;
     QColor mDiffuse;
     QColor mSpecular;
-    float mShininess;
+    float mShininess = 0.0f;
 };
 
 
diff --git a/src/3d/qgstessellatedpolygongeometry.cpp b/src/3d/qgstessellatedpolygongeometry.cpp
index e10194ef842b..163c2b6467ca 100644
--- a/src/3d/qgstessellatedpolygongeometry.cpp
+++ b/src/3d/qgstessellatedpolygongeometry.cpp
@@ -27,11 +27,7 @@
 
 QgsTessellatedPolygonGeometry::QgsTessellatedPolygonGeometry( QNode *parent )
   : Qt3DRender::QGeometry( parent )
-  , mPositionAttribute( nullptr )
-  , mNormalAttribute( nullptr )
 {
-  mWithNormals = true;
-
   mVertexBuffer = new Qt3DRender::QBuffer( Qt3DRender::QBuffer::VertexBuffer, this );
 
   QgsTessellator tmpTess( 0, 0, mWithNormals );
diff --git a/src/3d/qgstessellatedpolygongeometry.h b/src/3d/qgstessellatedpolygongeometry.h
index 8fc5b8450dbc..7d64554c8e41 100644
--- a/src/3d/qgstessellatedpolygongeometry.h
+++ b/src/3d/qgstessellatedpolygongeometry.h
@@ -51,7 +51,7 @@ class QgsTessellatedPolygonGeometry : public Qt3DRender::QGeometry
     Qt3DRender::QAttribute *mNormalAttribute = nullptr;
     Qt3DRender::QBuffer *mVertexBuffer = nullptr;
 
-    bool mWithNormals;
+    bool mWithNormals = true;
 };
 
 #endif // QGSTESSELLATEDPOLYGONGEOMETRY_H
diff --git a/src/3d/qgstilingscheme.cpp b/src/3d/qgstilingscheme.cpp
index 3d7c67225248..dc09bab22b5c 100644
--- a/src/3d/qgstilingscheme.cpp
+++ b/src/3d/qgstilingscheme.cpp
@@ -17,13 +17,6 @@
 
 #include "qgsrectangle.h"
 
-
-QgsTilingScheme::QgsTilingScheme()
-  : mMapOrigin()
-  , mBaseTileSide( 0 )
-{
-}
-
 QgsTilingScheme::QgsTilingScheme( const QgsRectangle &fullExtent, const QgsCoordinateReferenceSystem &crs )
   : mCrs( crs )
 {
diff --git a/src/3d/qgstilingscheme.h b/src/3d/qgstilingscheme.h
index 6d79caf3da34..829ffa2e25a8 100644
--- a/src/3d/qgstilingscheme.h
+++ b/src/3d/qgstilingscheme.h
@@ -33,7 +33,7 @@ class _3D_EXPORT QgsTilingScheme
 {
   public:
     //! Creates invalid tiling scheme
-    QgsTilingScheme();
+    QgsTilingScheme() = default;
 
     //! Creates tiling scheme where level 0 tile is centered at the full extent and the full extent completely fits into the level 0 tile
     QgsTilingScheme( const QgsRectangle &fullExtent, const QgsCoordinateReferenceSystem &crs );
@@ -54,7 +54,7 @@ class _3D_EXPORT QgsTilingScheme
 
   private:
     QgsPointXY mMapOrigin; //!< Origin point in map coordinates: (0,0) in the tiling scheme
-    double mBaseTileSide;  //!< Length of tile side at zoom level 0 in map coordinates
+    double mBaseTileSide = 0;  //!< Length of tile side at zoom level 0 in map coordinates
     QgsCoordinateReferenceSystem mCrs;  //!< CRS of the coordinates
 
 };
diff --git a/src/3d/symbols/qgsline3dsymbol.cpp b/src/3d/symbols/qgsline3dsymbol.cpp
index c1bc4497bab7..39aa1e1b26d7 100644
--- a/src/3d/symbols/qgsline3dsymbol.cpp
+++ b/src/3d/symbols/qgsline3dsymbol.cpp
@@ -15,16 +15,6 @@
 
 #include "qgsline3dsymbol.h"
 
-QgsLine3DSymbol::QgsLine3DSymbol()
-  : mAltClamping( AltClampRelative )
-  , mAltBinding( AltBindCentroid )
-  , mWidth( 2 )
-  , mHeight( 0 )
-  , mExtrusionHeight( 0 )
-{
-
-}
-
 QgsAbstract3DSymbol *QgsLine3DSymbol::clone() const
 {
   return new QgsLine3DSymbol( *this );
diff --git a/src/3d/symbols/qgsline3dsymbol.h b/src/3d/symbols/qgsline3dsymbol.h
index dad8fb3a8652..5c966706b25e 100644
--- a/src/3d/symbols/qgsline3dsymbol.h
+++ b/src/3d/symbols/qgsline3dsymbol.h
@@ -31,7 +31,8 @@
 class _3D_EXPORT QgsLine3DSymbol : public QgsAbstract3DSymbol
 {
   public:
-    QgsLine3DSymbol();
+    //! Constructor for QgsLine3DSymbol
+    QgsLine3DSymbol() = default;
 
     QString type() const override { return "line"; }
     QgsAbstract3DSymbol *clone() const override SIP_FACTORY;
@@ -70,12 +71,14 @@ class _3D_EXPORT QgsLine3DSymbol : public QgsAbstract3DSymbol
     void setMaterial( const QgsPhongMaterialSettings &material ) { mMaterial = material; }
 
   private:
-    AltitudeClamping mAltClamping;  //! how to handle altitude of vector features
-    AltitudeBinding mAltBinding;    //! how to handle clamping of vertices of individual features
-
-    float mWidth;            //!< Line width (horizontally)
-    float mHeight;           //!< Base height of polygons
-    float mExtrusionHeight;  //!< How much to extrude (0 means no walls)
+    //! how to handle altitude of vector features
+    AltitudeClamping mAltClamping = AltClampRelative;
+    //! how to handle clamping of vertices of individual features
+    AltitudeBinding mAltBinding = AltBindCentroid;
+
+    float mWidth = 2.0f;            //!< Line width (horizontally)
+    float mHeight = 0.0f;           //!< Base height of polygons
+    float mExtrusionHeight = 0.0f;  //!< How much to extrude (0 means no walls)
     QgsPhongMaterialSettings mMaterial;  //!< Defines appearance of objects
 };
 
diff --git a/src/3d/symbols/qgspoint3dsymbol.cpp b/src/3d/symbols/qgspoint3dsymbol.cpp
index 669d01c30a47..d1ef1c9ec58a 100644
--- a/src/3d/symbols/qgspoint3dsymbol.cpp
+++ b/src/3d/symbols/qgspoint3dsymbol.cpp
@@ -18,12 +18,6 @@
 #include "qgsreadwritecontext.h"
 #include "qgsxmlutils.h"
 
-
-QgsPoint3DSymbol::QgsPoint3DSymbol()
-  : mAltClamping( AltClampRelative )
-{
-}
-
 QgsAbstract3DSymbol *QgsPoint3DSymbol::clone() const
 {
   return new QgsPoint3DSymbol( *this );
diff --git a/src/3d/symbols/qgspoint3dsymbol.h b/src/3d/symbols/qgspoint3dsymbol.h
index 197bf45c240f..859d0d8221f3 100644
--- a/src/3d/symbols/qgspoint3dsymbol.h
+++ b/src/3d/symbols/qgspoint3dsymbol.h
@@ -32,7 +32,8 @@
 class _3D_EXPORT QgsPoint3DSymbol : public QgsAbstract3DSymbol
 {
   public:
-    QgsPoint3DSymbol();
+    //! Constructor for QgsPoint3DSymbol.
+    QgsPoint3DSymbol() = default;
 
     QString type() const override { return "point"; }
     QgsAbstract3DSymbol *clone() const override SIP_FACTORY;
@@ -84,7 +85,8 @@ class _3D_EXPORT QgsPoint3DSymbol : public QgsAbstract3DSymbol
     void setTransform( const QMatrix4x4 &transform ) { mTransform = transform; }
 
   private:
-    AltitudeClamping mAltClamping;  //! how to handle altitude of vector features
+    //! how to handle altitude of vector features
+    AltitudeClamping mAltClamping = AltClampRelative;
 
     QgsPhongMaterialSettings mMaterial;  //!< Defines appearance of objects
     Shape mShape = Cylinder;  //!< What kind of shape to use
diff --git a/src/3d/symbols/qgspolygon3dsymbol.cpp b/src/3d/symbols/qgspolygon3dsymbol.cpp
index 74b403c6572e..6057074144db 100644
--- a/src/3d/symbols/qgspolygon3dsymbol.cpp
+++ b/src/3d/symbols/qgspolygon3dsymbol.cpp
@@ -15,14 +15,6 @@
 
 #include "qgspolygon3dsymbol.h"
 
-QgsPolygon3DSymbol::QgsPolygon3DSymbol()
-  : mAltClamping( AltClampRelative )
-  , mAltBinding( AltBindCentroid )
-  , mHeight( 0 )
-  , mExtrusionHeight( 0 )
-{
-}
-
 QgsAbstract3DSymbol *QgsPolygon3DSymbol::clone() const
 {
   return new QgsPolygon3DSymbol( *this );
diff --git a/src/3d/symbols/qgspolygon3dsymbol.h b/src/3d/symbols/qgspolygon3dsymbol.h
index 554ca9f39cc4..4f1512d93bbf 100644
--- a/src/3d/symbols/qgspolygon3dsymbol.h
+++ b/src/3d/symbols/qgspolygon3dsymbol.h
@@ -31,7 +31,8 @@
 class _3D_EXPORT QgsPolygon3DSymbol : public QgsAbstract3DSymbol
 {
   public:
-    QgsPolygon3DSymbol();
+    //! Constructor for QgsPolygon3DSymbol
+    QgsPolygon3DSymbol() = default;
 
     QString type() const override { return "polygon"; }
     QgsAbstract3DSymbol *clone() const override SIP_FACTORY;
@@ -65,11 +66,13 @@ class _3D_EXPORT QgsPolygon3DSymbol : public QgsAbstract3DSymbol
     void setMaterial( const QgsPhongMaterialSettings &material ) { mMaterial = material; }
 
   private:
-    AltitudeClamping mAltClamping;  //! how to handle altitude of vector features
-    AltitudeBinding mAltBinding;    //! how to handle clamping of vertices of individual features
+    //! how to handle altitude of vector features
+    AltitudeClamping mAltClamping = AltClampRelative;
+    //! how to handle clamping of vertices of individual features
+    AltitudeBinding mAltBinding = AltBindCentroid;
 
-    float mHeight;           //!< Base height of polygons
-    float mExtrusionHeight;  //!< How much to extrude (0 means no walls)
+    float mHeight = 0.0f;           //!< Base height of polygons
+    float mExtrusionHeight = 0.0f;  //!< How much to extrude (0 means no walls)
     QgsPhongMaterialSettings mMaterial;  //!< Defines appearance of objects
 };
 
diff --git a/src/3d/terrain/qgsdemterraingenerator.cpp b/src/3d/terrain/qgsdemterraingenerator.cpp
index c6f46bff893c..0f053780dcc7 100644
--- a/src/3d/terrain/qgsdemterraingenerator.cpp
+++ b/src/3d/terrain/qgsdemterraingenerator.cpp
@@ -19,14 +19,6 @@
 
 #include "qgsrasterlayer.h"
 
-
-
-QgsDemTerrainGenerator::QgsDemTerrainGenerator()
-  : mResolution( 16 )
-  , mSkirtHeight( 10.f )
-{
-}
-
 QgsDemTerrainGenerator::~QgsDemTerrainGenerator()
 {
   delete mHeightMapGenerator;
diff --git a/src/3d/terrain/qgsdemterraingenerator.h b/src/3d/terrain/qgsdemterraingenerator.h
index 3e566797ce03..142b958a4087 100644
--- a/src/3d/terrain/qgsdemterraingenerator.h
+++ b/src/3d/terrain/qgsdemterraingenerator.h
@@ -36,7 +36,8 @@ class QgsDemHeightMapGenerator;
 class _3D_EXPORT QgsDemTerrainGenerator : public QgsTerrainGenerator
 {
   public:
-    QgsDemTerrainGenerator();
+    //! Constructor for QgsDemTerrainGenerator
+    QgsDemTerrainGenerator() = default;
     ~QgsDemTerrainGenerator();
 
     //! Sets raster layer with elevation model to be used for terrain generation
@@ -75,9 +76,9 @@ class _3D_EXPORT QgsDemTerrainGenerator : public QgsTerrainGenerator
     //! source layer for heights
     QgsMapLayerRef mLayer;
     //! how many vertices to place on one side of the tile
-    int mResolution;
+    int mResolution = 16;
     //! height of the "skirts" at the edges of tiles to hide cracks between adjacent cracks
-    float mSkirtHeight;
+    float mSkirtHeight = 10.f;
 };
 
 
diff --git a/src/3d/terrain/qgsterrainentity_p.cpp b/src/3d/terrain/qgsterrainentity_p.cpp
index ed03be5eb5c3..94c4e72998e0 100644
--- a/src/3d/terrain/qgsterrainentity_p.cpp
+++ b/src/3d/terrain/qgsterrainentity_p.cpp
@@ -57,7 +57,6 @@ QgsTerrainEntity::QgsTerrainEntity( int maxLevel, const Qgs3DMapSettings &map, Q
                       map.terrainGenerator()->rootChunkError( map ),
                       map.maxTerrainScreenError(), maxLevel, map.terrainGenerator(), parent )
   , mMap( map )
-  , mTerrainPicker( nullptr )
 {
   map.terrainGenerator()->setTerrain( this );
 
diff --git a/src/app/3d/qgs3dmapcanvas.cpp b/src/app/3d/qgs3dmapcanvas.cpp
index afa8e66f6fd5..9958f1c79dc3 100644
--- a/src/app/3d/qgs3dmapcanvas.cpp
+++ b/src/app/3d/qgs3dmapcanvas.cpp
@@ -25,10 +25,6 @@
 
 Qgs3DMapCanvas::Qgs3DMapCanvas( QWidget *parent )
   : QWidget( parent )
-  , mWindow3D( nullptr )
-  , mContainer( nullptr )
-  , mMap( nullptr )
-  , mScene( nullptr )
 {
   mWindow3D = new Qt3DExtras::Qt3DWindow;
   mContainer = QWidget::createWindowContainer( mWindow3D );
diff --git a/src/app/3d/qgs3dmapcanvasdockwidget.cpp b/src/app/3d/qgs3dmapcanvasdockwidget.cpp
index bd4d769adad2..946b76f1d49a 100644
--- a/src/app/3d/qgs3dmapcanvasdockwidget.cpp
+++ b/src/app/3d/qgs3dmapcanvasdockwidget.cpp
@@ -29,7 +29,6 @@
 
 Qgs3DMapCanvasDockWidget::Qgs3DMapCanvasDockWidget( QWidget *parent )
   : QgsDockWidget( parent )
-  , mMainCanvas( nullptr )
 {
   setAttribute( Qt::WA_DeleteOnClose );  // removes the dock widget from main window when
 
diff --git a/src/app/qgsattributesformproperties.cpp b/src/app/qgsattributesformproperties.cpp
index 27c0b99237c3..631d41d0f713 100644
--- a/src/app/qgsattributesformproperties.cpp
+++ b/src/app/qgsattributesformproperties.cpp
@@ -731,18 +731,7 @@ void QgsAttributesFormProperties::apply()
  * FieldConfig implementation
  */
 
-QgsAttributesFormProperties::FieldConfig::FieldConfig()
-  : mEditable( true )
-  , mEditableEnabled( true )
-  , mLabelOnTop( false )
-  , mConstraints( 0 )
-  , mConstraintDescription( QString() )
-  , mButton( nullptr )
-{
-}
-
 QgsAttributesFormProperties::FieldConfig::FieldConfig( QgsVectorLayer *layer, int idx )
-  : mButton( nullptr )
 {
   mAlias = layer->fields().at( idx ).alias();
   mComment = layer->fields().at( idx ).comment();
diff --git a/src/app/qgsattributesformproperties.h b/src/app/qgsattributesformproperties.h
index ee5378880d66..686e1527e428 100644
--- a/src/app/qgsattributesformproperties.h
+++ b/src/app/qgsattributesformproperties.h
@@ -66,12 +66,8 @@ class APP_EXPORT QgsAttributesFormProperties : public QWidget, private Ui_QgsAtt
 
     struct RelationEditorConfiguration
     {
-      RelationEditorConfiguration()
-        : showLinkButton( true )
-        , showUnlinkButton( true )
-      {}
-      bool showLinkButton;
-      bool showUnlinkButton;
+      bool showLinkButton = true;
+      bool showUnlinkButton = true;
     };
 
     class DnDTreeItemData : public QTreeWidgetItem
@@ -85,12 +81,7 @@ class APP_EXPORT QgsAttributesFormProperties : public QWidget, private Ui_QgsAtt
         };
 
         //do we need that
-        DnDTreeItemData()
-          : mType( Field )
-          , mColumnCount( 1 )
-          , mShowAsGroupBox( false )
-          , mShowLabel( true )
-        {}
+        DnDTreeItemData() = default;
 
         DnDTreeItemData( Type type, const QString &name )
           : mType( type )
@@ -124,11 +115,11 @@ class APP_EXPORT QgsAttributesFormProperties : public QWidget, private Ui_QgsAtt
         void setRelationEditorConfiguration( RelationEditorConfiguration relationEditorConfiguration );
 
       private:
-        Type mType;
+        Type mType = Field;
         QString mName;
-        int mColumnCount;
-        bool mShowAsGroupBox;
-        bool mShowLabel;
+        int mColumnCount = 1;
+        bool mShowAsGroupBox = false;
+        bool mShowLabel = true;
         QgsOptionalExpression mVisibilityExpression;
         RelationEditorConfiguration mRelationEditorConfiguration;
     };
@@ -139,14 +130,14 @@ class APP_EXPORT QgsAttributesFormProperties : public QWidget, private Ui_QgsAtt
      */
     struct FieldConfig
     {
-      FieldConfig();
+      FieldConfig() = default;
       FieldConfig( QgsVectorLayer *layer, int idx );
 
-      bool mEditable;
-      bool mEditableEnabled;
-      bool mLabelOnTop;
+      bool mEditable =  true ;
+      bool mEditableEnabled =  true ;
+      bool mLabelOnTop =  false ;
       QgsFieldConstraints mFieldConstraints;
-      QgsFieldConstraints::Constraints mConstraints;
+      QgsFieldConstraints::Constraints mConstraints = 0;
       QHash< QgsFieldConstraints::Constraint, QgsFieldConstraints::ConstraintStrength > mConstraintStrength;
       QString mConstraint;
       QString mConstraintDescription;
diff --git a/src/core/geometry/qgsabstractgeometry.h b/src/core/geometry/qgsabstractgeometry.h
index da060e7ddf53..60879ff70c5e 100644
--- a/src/core/geometry/qgsabstractgeometry.h
+++ b/src/core/geometry/qgsabstractgeometry.h
@@ -521,18 +521,18 @@ class CORE_EXPORT QgsAbstractGeometry
          */
         struct Level
         {
-          const QgsAbstractGeometry *g;  //!< Current geometry
-          int index;               //!< Ptr in the current geometry
+          const QgsAbstractGeometry *g = nullptr;  //!< Current geometry
+          int index = 0;               //!< Ptr in the current geometry
         };
 
         Level levels[3];  //!< Stack of levels - three levels should be sufficient (e.g. part index, ring index, vertex index)
-        int depth;        //!< At what depth level are we right now
+        int depth = -1;        //!< At what depth level are we right now
 
         void digDown();   //!< Prepare the stack of levels so that it points to a leaf child geometry
 
       public:
         //! Create invalid iterator
-        vertex_iterator() : depth( -1 ) {}
+        vertex_iterator() = default;
 
         //! Create vertex iterator for a geometry
         vertex_iterator( const QgsAbstractGeometry *g, int index );
@@ -720,7 +720,8 @@ inline T qgsgeometry_cast( const QgsAbstractGeometry *geom )
 class CORE_EXPORT QgsVertexIterator
 {
   public:
-    QgsVertexIterator(): g( nullptr ) {}
+    //! Constructor for QgsVertexIterator
+    QgsVertexIterator() = default;
 
     //! Constructs iterator for the given geometry
     QgsVertexIterator( const QgsAbstractGeometry *geometry )
@@ -755,7 +756,7 @@ class CORE_EXPORT QgsVertexIterator
 #endif
 
   private:
-    const QgsAbstractGeometry *g;
+    const QgsAbstractGeometry *g = nullptr;
     QgsAbstractGeometry::vertex_iterator i, n;
 
 };
diff --git a/src/core/layout/qgslayoutitemgroupundocommand.cpp b/src/core/layout/qgslayoutitemgroupundocommand.cpp
index eab2e2c72356..ce36ccaef703 100644
--- a/src/core/layout/qgslayoutitemgroupundocommand.cpp
+++ b/src/core/layout/qgslayoutitemgroupundocommand.cpp
@@ -26,7 +26,6 @@ QgsLayoutItemGroupUndoCommand::QgsLayoutItemGroupUndoCommand( State s, QgsLayout
   , mGroupUuid( group->uuid() )
   , mLayout( layout )
   , mState( s )
-  , mFirstRun( true )
 {
   const QList< QgsLayoutItem * > items = group->items();
   for ( QgsLayoutItem *i : items )
diff --git a/src/core/layout/qgslayoutitemgroupundocommand.h b/src/core/layout/qgslayoutitemgroupundocommand.h
index 5bed88ce479d..5b15ae7a6c03 100644
--- a/src/core/layout/qgslayoutitemgroupundocommand.h
+++ b/src/core/layout/qgslayoutitemgroupundocommand.h
@@ -64,7 +64,8 @@ class CORE_EXPORT QgsLayoutItemGroupUndoCommand: public QObject, public QUndoCom
     QSet<QString> mItemUuids;
     QgsLayout *mLayout = nullptr;
     State mState;
-    bool mFirstRun = true; //flag to prevent execution when the command is pushed to the QUndoStack
+    //! Flag to prevent execution when the command is pushed to the QUndoStack
+    bool mFirstRun = true;
 
     //changes between added / removed state
     void switchState();
diff --git a/src/gui/layout/qgslayoutitemwidget.cpp b/src/gui/layout/qgslayoutitemwidget.cpp
index 2555cb5f63a5..379af5939109 100644
--- a/src/gui/layout/qgslayoutitemwidget.cpp
+++ b/src/gui/layout/qgslayoutitemwidget.cpp
@@ -195,11 +195,6 @@ void QgsLayoutItemPropertiesWidget::updateVariables()
 QgsLayoutItemPropertiesWidget::QgsLayoutItemPropertiesWidget( QWidget *parent, QgsLayoutItem *item )
   : QWidget( parent )
   , mConfigObject( new QgsLayoutConfigObject( this, item ) )
-  , mFreezeXPosSpin( false )
-  , mFreezeYPosSpin( false )
-  , mFreezeWidthSpin( false )
-  , mFreezeHeightSpin( false )
-  , mFreezePageSpin( false )
 {
   setupUi( this );