diff --git a/.ci/travis/linux/install.sh b/.ci/travis/linux/install.sh
index 111c3ffa86c..0b68b220d72 100755
--- a/.ci/travis/linux/install.sh
+++ b/.ci/travis/linux/install.sh
@@ -52,7 +52,6 @@ CMAKE_FLAGS="
       -DWITH_QWTPOLAR=OFF
       -DWITH_APIDOC=OFF
       -DWITH_ASTYLE=OFF
-      -DWITH_INTERNAL_YAML=OFF
       -DDISABLE_DEPRECATED=ON
       -DCXX_EXTRA_FLAGS=${CLANG_WARNINGS}
       "
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 117eb8d8471..66b9ec14c13 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,7 +21,7 @@ MESSAGE(STATUS "QGIS version: ${COMPLETE_VERSION} ${RELEASE_NAME} (${QGIS_VERSIO
 #############################################################
 # CMake settings
 
-CMAKE_MINIMUM_REQUIRED(VERSION 2.8.6)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.0.0)
 
 SET(CMAKE_COLOR_MAKEFILE ON)
 
diff --git a/cmake/SIPMacros.cmake b/cmake/SIPMacros.cmake
index 501eb6afa4c..e58fb409666 100644
--- a/cmake/SIPMacros.cmake
+++ b/cmake/SIPMacros.cmake
@@ -37,7 +37,7 @@
 
 SET(SIP_INCLUDES)
 SET(SIP_TAGS)
-SET(SIP_CONCAT_PARTS 8)
+SET(SIP_CONCAT_PARTS 10)
 SET(SIP_DISABLE_FEATURES)
 SET(SIP_EXTRA_OPTIONS)
 SET(SIP_EXTRA_OBJECTS)
@@ -79,10 +79,13 @@ MACRO(GENERATE_SIP_PYTHON_MODULE_CODE MODULE_NAME MODULE_SIP CPP_FILES)
   # Suppress warnings
   IF(PEDANTIC)
     IF(MSVC)
-      # 4996 deprecation warnings (bindings re-export deprecated methods)
-      # 4701 potentially uninitialized variable used (sip generated code)
-      # 4702 unreachable code (sip generated code)
-      ADD_DEFINITIONS( /wd4996 /wd4701 /wd4702 )
+      ADD_DEFINITIONS(
+        /wd4189  # local variable is initialized but not referenced
+        /wd4996  # deprecation warnings (bindings re-export deprecated methods)
+        /wd4701  # potentially uninitialized variable used (sip generated code)
+        /wd4702  # unreachable code (sip generated code)
+        /wd4703  # potentially uninitialized local pointer variable 'sipType' used
+      )
     ELSE(MSVC)
       # disable all warnings
       ADD_DEFINITIONS( -w -Wno-deprecated-declarations )
diff --git a/doc/overview.t2t b/doc/overview.t2t
index bed50d9a948..1dfb2f588d6 100644
--- a/doc/overview.t2t
+++ b/doc/overview.t2t
@@ -8,7 +8,7 @@ Following a summary of the required dependencies for building:
 
 Required build tools:
 
-- CMake >= 2.8.6
+- CMake >= 3.0.0
 - Flex >= 2.5.6
 - Bison >= 2.4
 -
diff --git a/python/gui/qgisinterface.sip b/python/gui/qgisinterface.sip
index 4ab99eee6dc..ce148fe136f 100644
--- a/python/gui/qgisinterface.sip
+++ b/python/gui/qgisinterface.sip
@@ -577,7 +577,6 @@ Unregister a previously registered action. (e.g. when plugin is going to be unlo
 %End
 
 
-
     virtual QMenu *projectMenu() = 0;
 %Docstring
  :rtype: QMenu
diff --git a/scripts/sipify.pl b/scripts/sipify.pl
index 3bdea4ee9ed..0aa88fbf408 100755
--- a/scripts/sipify.pl
+++ b/scripts/sipify.pl
@@ -463,8 +463,8 @@ while ($LINE_IDX < $LINE_COUNT){
     if ( $LINE =~ m/^\s*friend class \w+/ ){
         next;
     }
-    # Skip Q_OBJECT, Q_PROPERTY, Q_ENUM, Q_GADGET
-    if ($LINE =~ m/^\s*Q_(OBJECT|ENUMS|PROPERTY|GADGET|DECLARE_METATYPE|DECLARE_TYPEINFO|DECL_DEPRECATED).*?$/){
+    # Skip Q_OBJECT, Q_PROPERTY, Q_ENUM, Q_GADGET etc.
+    if ($LINE =~ m/^\s*Q_(OBJECT|ENUMS|PROPERTY|GADGET|DECLARE_METATYPE|DECLARE_TYPEINFO|DECL_DEPRECATED|NOWARN_DEPRECATED_(PUSH|POP)).*?$/){
         next;
     }
 
diff --git a/scripts/spell_check/check_spelling.sh b/scripts/spell_check/check_spelling.sh
index 9b6e1b9c933..ea435ed890d 100755
--- a/scripts/spell_check/check_spelling.sh
+++ b/scripts/spell_check/check_spelling.sh
@@ -82,7 +82,7 @@ declare -A GLOBREP_IGNORE=()
 ERRORFOUND=NO
 
 for I in $(seq -f '%02g' 0  $(($SPLIT-1)) ) ; do
-  ( [[ "$INTERACTIVE" =~ YES ]] || [[ "$TRAVIS" =~ true ]] ) && printf "Progress: %d/%d\n" $I $SPLIT
+  ( [[ "$INTERACTIVE" =~ YES ]] || [[ "$TRAVIS" =~ true ]] ) && printf "Progress: %d/%d\n" $(( I + 1 )) $SPLIT
   SPELLFILE=spelling$I~
 
   # if correction contains an uppercase letter and is the same as the error character wise, this means that the error is searched as a full word and case sensitive (not incorporated in a bigger one)
diff --git a/src/app/dwg/libdxfrw/intern/dwgutil.cpp b/src/app/dwg/libdxfrw/intern/dwgutil.cpp
index 3213e5726a7..ad8ca31c977 100644
--- a/src/app/dwg/libdxfrw/intern/dwgutil.cpp
+++ b/src/app/dwg/libdxfrw/intern/dwgutil.cpp
@@ -16,6 +16,16 @@
 #include "rscodec.h"
 #include "../libdwgr.h"
 
+#if __cplusplus >= 201500
+#define FALLTHROUGH [[fallthrough]];
+#elif defined(__clang__)
+#define FALLTHROUGH //[[clang::fallthrough]]
+#elif defined(__GNUC__) && __GNUC__ >= 7
+#define FALLTHROUGH [[gnu::fallthrough]];
+#else
+#define FALLTHROUGH
+#endif
+
 #include "qgslogger.h"
 
 /** Utility function
@@ -486,6 +496,9 @@ void dwgCompressor::copyCompBytes21( duint8 *cbuf, duint8 *dbuf, duint32 l, duin
       for ( int i = 1; i < 5; i++ )
         dbuf[dix++] = cbuf[six + i];
       dbuf[dix] = cbuf[six];
+
+      FALLTHROUGH
+
     case 8: //OK
       for ( int i = 0; i < 8; i++ ) //RLZ 4[0],4[4] or 4[4],4[0]
         dbuf[dix++] = cbuf[six++];
diff --git a/src/app/dwg/libdxfrw/libdxfrw.cpp b/src/app/dwg/libdxfrw/libdxfrw.cpp
index 1a48bc0b383..4a39578d60a 100644
--- a/src/app/dwg/libdxfrw/libdxfrw.cpp
+++ b/src/app/dwg/libdxfrw/libdxfrw.cpp
@@ -24,6 +24,16 @@
 
 #include "qgslogger.h"
 
+#if __cplusplus >= 201500
+#define FALLTHROUGH [[fallthrough]];
+#elif defined(__clang__)
+#define FALLTHROUGH //[[clang::fallthrough]]
+#elif defined(__GNUC__) && __GNUC__ >= 7
+#define FALLTHROUGH [[gnu::fallthrough]];
+#else
+#define FALLTHROUGH
+#endif
+
 #define FIRSTHANDLE 48
 
 #if 0
@@ -3047,6 +3057,8 @@ bool dxfRW::processPolyline()
         {
           processVertex( &pl );
         }
+
+        FALLTHROUGH
       }
       default:
         pl.parseCode( code, reader );
@@ -3079,6 +3091,8 @@ bool dxfRW::processVertex( DRW_Polyline *pl )
         {
           v = new DRW_Vertex(); //another vertex
         }
+
+        FALLTHROUGH
       }
       default:
         v->parseCode( code, reader );
diff --git a/src/app/dwg/qgsdwgimporter.cpp b/src/app/dwg/qgsdwgimporter.cpp
index 0459affbb97..57217a9b5ae 100644
--- a/src/app/dwg/qgsdwgimporter.cpp
+++ b/src/app/dwg/qgsdwgimporter.cpp
@@ -1395,7 +1395,7 @@ void QgsDwgImporter::addEllipse( const DRW_Ellipse &data )
 
 bool QgsDwgImporter::curveFromLWPolyline( const DRW_LWPolyline &data, QgsCompoundCurve &cc )
 {
-  int vertexnum = data.vertlist.size();
+  size_t vertexnum = data.vertlist.size();
   if ( vertexnum == 0 )
   {
     QgsDebugMsg( "polyline without points" );
@@ -1407,7 +1407,7 @@ bool QgsDwgImporter::curveFromLWPolyline( const DRW_LWPolyline &data, QgsCompoun
   std::vector<DRW_Vertex2D *>::size_type n = data.flags & 1 ? vertexnum + 1 : vertexnum;
   for ( std::vector<DRW_Vertex2D *>::size_type i = 0; i < n; i++ )
   {
-    int i0 = i % vertexnum;
+    size_t i0 = i % vertexnum;
 
     Q_ASSERT( data.vertlist[i0] != nullptr );
     QgsDebugMsgLevel( QString( "%1: %2,%3 bulge:%4" ).arg( i ).arg( data.vertlist[i0]->x ).arg( data.vertlist[i0]->y ).arg( data.vertlist[i0]->bulge ), 5 );
@@ -1439,7 +1439,7 @@ bool QgsDwgImporter::curveFromLWPolyline( const DRW_LWPolyline &data, QgsCompoun
 
     if ( hasBulge && i < n - 1 )
     {
-      int i1 = ( i + 1 ) % vertexnum;
+      size_t i1 = ( i + 1 ) % vertexnum;
 
       double a = 2.0 * atan( data.vertlist[i]->bulge );
       double dx = data.vertlist[i1]->x - data.vertlist[i0]->x;
@@ -1461,7 +1461,7 @@ bool QgsDwgImporter::curveFromLWPolyline( const DRW_LWPolyline &data, QgsCompoun
 
 void QgsDwgImporter::addLWPolyline( const DRW_LWPolyline &data )
 {
-  int vertexnum = data.vertlist.size();
+  size_t vertexnum = data.vertlist.size();
   if ( vertexnum == 0 )
   {
     QgsDebugMsg( "LWPolyline without vertices" );
@@ -1476,8 +1476,8 @@ void QgsDwgImporter::addLWPolyline( const DRW_LWPolyline &data )
   std::vector<DRW_Vertex2D *>::size_type n = data.flags & 1 ? vertexnum : vertexnum - 1;
   for ( std::vector<DRW_Vertex2D *>::size_type i = 0; i < n; i++ )
   {
-    int i0 = i % vertexnum;
-    int i1 = ( i + 1 ) % vertexnum;
+    size_t i0 = i % vertexnum;
+    size_t i1 = ( i + 1 ) % vertexnum;
 
     QgsPoint p0( QgsWkbTypes::PointZ, data.vertlist[i0]->x, data.vertlist[i0]->y, data.elevation );
     QgsPoint p1( QgsWkbTypes::PointZ, data.vertlist[i1]->x, data.vertlist[i1]->y, data.elevation );
@@ -1660,7 +1660,7 @@ void QgsDwgImporter::addLWPolyline( const DRW_LWPolyline &data )
 
 void QgsDwgImporter::addPolyline( const DRW_Polyline &data )
 {
-  int vertexnum = data.vertlist.size();
+  size_t vertexnum = data.vertlist.size();
   if ( vertexnum == 0 )
   {
     QgsDebugMsg( "Polyline without vertices" );
@@ -1675,8 +1675,8 @@ void QgsDwgImporter::addPolyline( const DRW_Polyline &data )
   std::vector<DRW_Vertex *>::size_type n = data.flags & 1 ? vertexnum : vertexnum - 1;
   for ( std::vector<DRW_Vertex *>::size_type i = 0; i < n; i++ )
   {
-    int i0 = i % vertexnum;
-    int i1 = ( i + 1 ) % vertexnum;
+    size_t i0 = i % vertexnum;
+    size_t i1 = ( i + 1 ) % vertexnum;
 
     QgsPoint p0( QgsWkbTypes::PointZ, data.vertlist[i0]->basePoint.x, data.vertlist[i0]->basePoint.y, data.vertlist[i0]->basePoint.z );
     QgsPoint p1( QgsWkbTypes::PointZ, data.vertlist[i1]->basePoint.x, data.vertlist[i1]->basePoint.y, data.vertlist[i1]->basePoint.z );
@@ -1906,24 +1906,24 @@ static std::vector<double> knotu( const DRW_Spline &data, size_t num, size_t ord
   }
 }
 
-static std::vector<double> rbasis( int c, double t, int npts,
+static std::vector<double> rbasis( size_t c, double t, size_t npts,
                                    const std::vector<double> &x,
                                    const std::vector<double> &h )
 {
-  int nplusc = npts + c;
+  size_t nplusc = npts + c;
   std::vector<double> temp( nplusc, 0. );
 
   // calculate the first order nonrational basis functions n[i]
-  for ( int i = 0; i < nplusc - 1; ++i )
+  for ( size_t i = 0; i < nplusc - 1; ++i )
   {
     if ( t >= x[i] && t < x[i + 1] )
       temp[i] = 1;
   }
 
   // calculate the higher order nonrational base functions
-  for ( int k = 2; k <= c; ++k )
+  for ( size_t k = 2; k <= c; ++k )
   {
-    for ( int i = 0; i < nplusc - k; ++i )
+    for ( size_t i = 0; i < nplusc - k; ++i )
     {
       // if the lower order basis function is zero skip the calculation
       if ( temp[i] != 0 )
@@ -1941,7 +1941,7 @@ static std::vector<double> rbasis( int c, double t, int npts,
 
   // calculate sum for denominator of rational basis functions
   double sum = 0.;
-  for ( int i = 0; i < npts; ++i )
+  for ( size_t i = 0; i < npts; ++i )
   {
     sum += temp[i] * h[i];
   }
@@ -1951,7 +1951,7 @@ static std::vector<double> rbasis( int c, double t, int npts,
   // form rational basis functions and put in r vector
   if ( sum != 0.0 )
   {
-    for ( int i = 0; i < npts; i++ )
+    for ( size_t i = 0; i < npts; i++ )
     {
       r[i] = ( temp[i] * h[i] ) / sum;
     }
@@ -1969,7 +1969,7 @@ static void rbspline( const DRW_Spline &data,
                       const std::vector<double> &h,
                       std::vector<QgsPointXY> &p )
 {
-  int nplusc = npts + k;
+  size_t nplusc = npts + k;
 
   // generate the open knot vector
   std::vector<double> x( knot( data, npts, k ) );
diff --git a/src/app/qgisappinterface.h b/src/app/qgisappinterface.h
index c23e6ac3586..ae6225b36cb 100644
--- a/src/app/qgisappinterface.h
+++ b/src/app/qgisappinterface.h
@@ -33,6 +33,7 @@ class QgisApp;
  * plugin.
  */
 
+Q_NOWARN_DEPRECATED_PUSH
 class APP_EXPORT QgisAppInterface : public QgisInterface
 {
     Q_OBJECT
@@ -519,5 +520,6 @@ class APP_EXPORT QgisAppInterface : public QgisInterface
     //! Pointer to the PluginManagerInterface object
     QgsAppPluginManagerInterface pluginManagerIface;
 };
+Q_NOWARN_DEPRECATED_POP
 
 #endif //#define QGISAPPINTERFACE_H
diff --git a/src/core/geometry/qgsgeometrymakevalid.cpp b/src/core/geometry/qgsgeometrymakevalid.cpp
index 98a0df2b06c..275bc04c198 100644
--- a/src/core/geometry/qgsgeometrymakevalid.cpp
+++ b/src/core/geometry/qgsgeometrymakevalid.cpp
@@ -159,8 +159,10 @@ static GEOSGeometry *LWGEOM_GEOS_buildArea( const GEOSGeometry *geom_in, QString
   }
   catch ( GEOSException &e )
   {
+    Q_NOWARN_UNREACHABLE_PUSH
     errorMessage = QString( "GEOSPolygonize(): %1" ).arg( e.what() );
     return nullptr;
+    Q_NOWARN_UNREACHABLE_POP
   }
 
   // We should now have a collection
@@ -505,9 +507,11 @@ static GEOSGeometry *LWGEOM_GEOS_makeValidPolygon( const GEOSGeometry *gin, QStr
     }
     catch ( GEOSException &e )
     {
+      Q_NOWARN_UNREACHABLE_PUSH
       GEOSGeom_destroy_r( handle, geos_bound );
       errorMessage = QString( "GEOSGeom_extractUniquePoints(): %1" ).arg( e.what() );
       return nullptr;
+      Q_NOWARN_UNREACHABLE_POP
     }
 
     try
@@ -516,10 +520,12 @@ static GEOSGeometry *LWGEOM_GEOS_makeValidPolygon( const GEOSGeometry *gin, QStr
     }
     catch ( GEOSException &e )
     {
+      Q_NOWARN_UNREACHABLE_PUSH
       GEOSGeom_destroy_r( handle, geos_bound );
       GEOSGeom_destroy_r( handle, pi );
       errorMessage = QString( "GEOSGeom_extractUniquePoints(): %1" ).arg( e.what() );
       return nullptr;
+      Q_NOWARN_UNREACHABLE_POP
     }
 
     try
@@ -528,11 +534,13 @@ static GEOSGeometry *LWGEOM_GEOS_makeValidPolygon( const GEOSGeometry *gin, QStr
     }
     catch ( GEOSException &e )
     {
+      Q_NOWARN_UNREACHABLE_PUSH
       GEOSGeom_destroy_r( handle, geos_bound );
       GEOSGeom_destroy_r( handle, pi );
       GEOSGeom_destroy_r( handle, po );
       errorMessage = QString( "GEOSDifference(): %1" ).arg( e.what() );
       return nullptr;
+      Q_NOWARN_UNREACHABLE_POP
     }
 
     GEOSGeom_destroy_r( handle, pi );
@@ -547,9 +555,11 @@ static GEOSGeometry *LWGEOM_GEOS_makeValidPolygon( const GEOSGeometry *gin, QStr
   }
   catch ( GEOSException &e )
   {
+    Q_NOWARN_UNREACHABLE_PUSH
     errorMessage = QString( "GEOSGeom_createEmptyPolygon(): %1" ).arg( e.what() );
     GEOSGeom_destroy_r( handle, geos_cut_edges );
     return nullptr;
+    Q_NOWARN_UNREACHABLE_POP
   }
 
   // See if an area can be build with the remaining edges
@@ -594,12 +604,14 @@ static GEOSGeometry *LWGEOM_GEOS_makeValidPolygon( const GEOSGeometry *gin, QStr
     }
     catch ( GEOSException &e )
     {
+      Q_NOWARN_UNREACHABLE_PUSH
       // We did check for empty area already so
       // this must be some other error
       errorMessage = QString( "GEOSBoundary() threw an error: %1" ).arg( e.what() );
       GEOSGeom_destroy_r( handle, new_area );
       GEOSGeom_destroy_r( handle, geos_area );
       return nullptr;
+      Q_NOWARN_UNREACHABLE_POP
     }
 
     // Now symdif new and old area
@@ -609,12 +621,14 @@ static GEOSGeometry *LWGEOM_GEOS_makeValidPolygon( const GEOSGeometry *gin, QStr
     }
     catch ( GEOSException &e )
     {
+      Q_NOWARN_UNREACHABLE_PUSH
       GEOSGeom_destroy_r( handle, geos_cut_edges );
       GEOSGeom_destroy_r( handle, new_area );
       GEOSGeom_destroy_r( handle, new_area_bound );
       GEOSGeom_destroy_r( handle, geos_area );
       errorMessage = QString( "GEOSSymDifference() threw an error: %1" ).arg( e.what() );
       return nullptr;
+      Q_NOWARN_UNREACHABLE_POP
     }
 
     GEOSGeom_destroy_r( handle, geos_area );
@@ -636,11 +650,13 @@ static GEOSGeometry *LWGEOM_GEOS_makeValidPolygon( const GEOSGeometry *gin, QStr
     }
     catch ( GEOSException &e )
     {
+      Q_NOWARN_UNREACHABLE_PUSH
       GEOSGeom_destroy_r( handle, geos_cut_edges );
       GEOSGeom_destroy_r( handle, new_area_bound );
       GEOSGeom_destroy_r( handle, geos_area );
       errorMessage = QString( "GEOSDifference() threw an error: %1" ).arg( e.what() );
       return nullptr;
+      Q_NOWARN_UNREACHABLE_POP
     }
     GEOSGeom_destroy_r( handle, geos_cut_edges );
     GEOSGeom_destroy_r( handle, new_area_bound );
@@ -688,9 +704,11 @@ static GEOSGeometry *LWGEOM_GEOS_makeValidPolygon( const GEOSGeometry *gin, QStr
     }
     catch ( GEOSException &e )
     {
+      Q_NOWARN_UNREACHABLE_PUSH
       errorMessage = QString( "GEOSGeom_createCollection() threw an error: %1" ).arg( e.what() );
       // TODO: cleanup!
       return nullptr;
+      Q_NOWARN_UNREACHABLE_POP
     }
   }
 
@@ -856,9 +874,11 @@ static GEOSGeometry *LWGEOM_GEOS_makeValid( const GEOSGeometry *gin, QString &er
   }
   catch ( GEOSException &e )
   {
+    Q_NOWARN_UNREACHABLE_PUSH
     // I don't think should ever happen
     errorMessage = QString( "GEOSisValid(): %1" ).arg( e.what() );
     return nullptr;
+    Q_NOWARN_UNREACHABLE_POP
   }
 
   // make what we got valid
diff --git a/src/core/gps/tok.c b/src/core/gps/tok.c
index 0434eb56c9a..c0cf8ce9b86 100644
--- a/src/core/gps/tok.c
+++ b/src/core/gps/tok.c
@@ -26,6 +26,14 @@
 
 //! \file tok.h
 
+#if defined(__clang__)
+#define FALLTHROUGH //[[clang::fallthrough]]
+#elif defined(__GNUC__) && __GNUC__ >= 7
+#define FALLTHROUGH __attribute__((fallthrough));
+#else
+#define FALLTHROUGH
+#endif
+
 #include "tok.h"
 
 #include <stdarg.h>
@@ -165,15 +173,21 @@ int nmea_scanf( const char *buff, int buff_sz, const char *format, ... )
         width = 0;
         beg_fmt = format;
         tok_type = NMEA_TOKS_WIDTH;
-      //intentional fall-through
+
+        FALLTHROUGH
+
       case NMEA_TOKS_WIDTH:
+      {
         if ( isdigit( *format ) )
           break;
-        {
-          tok_type = NMEA_TOKS_TYPE;
-          if ( format > beg_fmt )
-            width = nmea_atoi( beg_fmt, ( int )( format - beg_fmt ), 10 );
-        }
+
+        tok_type = NMEA_TOKS_TYPE;
+        if ( format > beg_fmt )
+          width = nmea_atoi( beg_fmt, ( int )( format - beg_fmt ), 10 );
+
+        FALLTHROUGH
+      }
+
       case NMEA_TOKS_TYPE:
         beg_tok = buff;
 
diff --git a/src/core/pal/geomfunction.cpp b/src/core/pal/geomfunction.cpp
index a0cf1b25cee..b61b5d0e3f0 100644
--- a/src/core/pal/geomfunction.cpp
+++ b/src/core/pal/geomfunction.cpp
@@ -363,8 +363,10 @@ bool GeomFunction::containsCandidate( const GEOSPreparedGeometry *geom, double x
   }
   catch ( GEOSException &e )
   {
+    Q_NOWARN_UNREACHABLE_PUSH
     QgsMessageLog::logMessage( QObject::tr( "Exception: %1" ).arg( e.what() ), QObject::tr( "GEOS" ) );
     return false;
+    Q_NOWARN_UNREACHABLE_POP
   }
 }
 
diff --git a/src/core/providers/memory/qgsmemoryproviderutils.cpp b/src/core/providers/memory/qgsmemoryproviderutils.cpp
index cccc63c4cec..b0eb108be55 100644
--- a/src/core/providers/memory/qgsmemoryproviderutils.cpp
+++ b/src/core/providers/memory/qgsmemoryproviderutils.cpp
@@ -45,9 +45,9 @@ QString memoryLayerFieldType( QVariant::Type type )
       return QStringLiteral( "datetime" );
 
     default:
-      return QStringLiteral( "string" );
+      break;
   }
-  return QStringLiteral( "string" ); // no warnings
+  return QStringLiteral( "string" );
 }
 
 QgsVectorLayer *QgsMemoryProviderUtils::createMemoryLayer( const QString &name, const QgsFields &fields, QgsWkbTypes::Type geometryType, const QgsCoordinateReferenceSystem &crs )
diff --git a/src/core/qgis.cpp b/src/core/qgis.cpp
index 460476ad70d..e5e7350c94a 100644
--- a/src/core/qgis.cpp
+++ b/src/core/qgis.cpp
@@ -232,7 +232,7 @@ QString qgsVsiPrefix( const QString &path )
 uint qHash( const QVariant &variant )
 {
   if ( !variant.isValid() || variant.isNull() )
-    return -1;
+    return std::numeric_limits<uint>::max();
 
   switch ( variant.type() )
   {
@@ -290,8 +290,8 @@ uint qHash( const QVariant &variant )
     case QVariant::RegExp:
       return qHash( variant.toString() );
     default:
-      return -1;
+      break;
   }
 
-  return -1;
+  return std::numeric_limits<uint>::max();
 }
diff --git a/src/core/qgis.h b/src/core/qgis.h
index 313a16e9964..3cac2097084 100644
--- a/src/core/qgis.h
+++ b/src/core/qgis.h
@@ -356,20 +356,35 @@ typedef unsigned long long qgssize;
 
 #ifndef SIP_RUN
 #if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)) || defined(__clang__)
+
 #define Q_NOWARN_DEPRECATED_PUSH \
   _Pragma("GCC diagnostic push") \
   _Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"");
 #define Q_NOWARN_DEPRECATED_POP \
   _Pragma("GCC diagnostic pop");
+#define Q_NOWARN_UNREACHABLE_PUSH
+#define Q_NOWARN_UNREACHABLE_POP
+
 #elif defined(_MSC_VER)
+
 #define Q_NOWARN_DEPRECATED_PUSH \
   __pragma(warning(push)) \
   __pragma(warning(disable:4996))
 #define Q_NOWARN_DEPRECATED_POP \
   __pragma(warning(pop))
+#define Q_NOWARN_UNREACHABLE_PUSH \
+  __pragma(warning(push)) \
+  __pragma(warning(disable:4702))
+#define Q_NOWARN_UNREACHABLE_POP \
+  __pragma(warning(pop))
+
 #else
+
 #define Q_NOWARN_DEPRECATED_PUSH
 #define Q_NOWARN_DEPRECATED_POP
+#define Q_NOWARN_UNREACHABLE_PUSH
+#define Q_NOWARN_UNREACHABLE_POP
+
 #endif
 #endif
 
diff --git a/src/core/qgsstacktrace.cpp b/src/core/qgsstacktrace.cpp
index a0bafc8315c..081d5fc90fb 100644
--- a/src/core/qgsstacktrace.cpp
+++ b/src/core/qgsstacktrace.cpp
@@ -49,7 +49,7 @@ QVector<QgsStackTrace::StackLine> QgsStackTrace::trace( _EXCEPTION_POINTERS *Exc
     paths = QgsStackTrace::mSymbolPaths.toStdString().c_str();
   }
 
-  BOOL success = SymInitialize( process, paths, TRUE );
+  SymInitialize( process, paths, TRUE );
 
   // StackWalk64() may modify context record passed to it, so we will
   // use a copy.
diff --git a/src/core/qgsunittypes.cpp b/src/core/qgsunittypes.cpp
index 0ff6c67ddaa..156c95d66df 100644
--- a/src/core/qgsunittypes.cpp
+++ b/src/core/qgsunittypes.cpp
@@ -1485,6 +1485,8 @@ QgsUnitTypes::DistanceValue QgsUnitTypes::scaledDistance( double distance, QgsUn
 QgsUnitTypes::AreaValue QgsUnitTypes::scaledArea( double area, QgsUnitTypes::AreaUnit unit, int decimals, bool keepBaseUnit )
 {
   AreaValue result;
+  result.value = -1.0;
+  result.unit = AreaUnknownUnit;
 
   // If we are not forced to keep the base units, switch to meter calculation
   if ( unit == AreaSquareMillimeters )
diff --git a/src/core/qgsvectorlayerutils.cpp b/src/core/qgsvectorlayerutils.cpp
index b37a921730b..05b5d30b183 100644
--- a/src/core/qgsvectorlayerutils.cpp
+++ b/src/core/qgsvectorlayerutils.cpp
@@ -127,7 +127,7 @@ QVariant QgsVectorLayerUtils::createUniqueValue( const QgsVectorLayer *layer, in
 
       default:
         // todo other types - dates? times?
-        return QVariant();
+        break;
     }
   }
 
diff --git a/src/core/qgsziputils.cpp b/src/core/qgsziputils.cpp
index b43222673f9..3f4803cabdb 100644
--- a/src/core/qgsziputils.cpp
+++ b/src/core/qgsziputils.cpp
@@ -139,8 +139,8 @@ bool QgsZipUtils::zip( const QString &zipFilename, const QStringList &files )
       {
         QString err = QObject::tr( "Error input file does not exist: '%1'" ).arg( file );
         QgsMessageLog::logMessage( err, QStringLiteral( "QgsZipUtils" ) );
-        return false;
         zip_close( z );
+        return false;
       }
 
       zip_source *src = zip_source_file( z, file.toStdString().c_str(), 0, 0 );
diff --git a/src/gui/layout/qgslayoutruler.cpp b/src/gui/layout/qgslayoutruler.cpp
index 931dc8a5ed0..b73c78dde40 100644
--- a/src/gui/layout/qgslayoutruler.cpp
+++ b/src/gui/layout/qgslayoutruler.cpp
@@ -419,7 +419,7 @@ void QgsLayoutRuler::drawSmallDivisions( QPainter *painter, double startPos, int
   double smallMarkerPos = startPos;
   double smallDivisionSpacing = rulerScale / numDivisions;
 
-  double pixelCoord;
+  double pixelCoord = 0.0;
 
   //draw numDivisions small divisions
   for ( int i = 0; i < numDivisions; ++i )
diff --git a/src/gui/qgisinterface.h b/src/gui/qgisinterface.h
index a18edb0ab7b..8be12cb54aa 100644
--- a/src/gui/qgisinterface.h
+++ b/src/gui/qgisinterface.h
@@ -1,6 +1,6 @@
 /***************************************************************************
                           qgisinterface.h
- Interface class for exposing functions in QgisApp for use by plugins
+  Interface class for exposing functions in QgisApp for use by plugins
                              -------------------
   begin                : 2004-02-11
   copyright            : (C) 2004 by Gary E.Sherman
@@ -69,6 +69,7 @@ class QgsStatusBar;
  * could provide their own implementation to be able to use plugins.
  */
 
+Q_NOWARN_DEPRECATED_PUSH
 class GUI_EXPORT QgisInterface : public QObject
 {
     Q_OBJECT
@@ -459,7 +460,6 @@ class GUI_EXPORT QgisInterface : public QObject
 #endif
     virtual void openURL( const QString &url, bool useQgisDocDirectory = true ) = 0 SIP_DEPRECATED;
 
-
     /** Accessors for inserting items into menus and toolbars.
      * An item can be inserted before any existing action.
      */
@@ -797,5 +797,6 @@ class GUI_EXPORT QgisInterface : public QObject
      */
     void layerSavedAs( QgsMapLayer *l, const QString &path );
 };
+Q_NOWARN_DEPRECATED_POP
 
 #endif //#ifndef QGISINTERFACE_H
diff --git a/src/gui/qgsfontbutton.cpp b/src/gui/qgsfontbutton.cpp
index 19c68948352..06d6202805e 100644
--- a/src/gui/qgsfontbutton.cpp
+++ b/src/gui/qgsfontbutton.cpp
@@ -173,7 +173,7 @@ bool QgsFontButton::event( QEvent *e )
   {
     QHelpEvent *helpEvent = static_cast< QHelpEvent *>( e );
     QString toolTip;
-    double fontSize;
+    double fontSize = 0.0;
     switch ( mMode )
     {
       case ModeTextRenderer:
diff --git a/src/gui/raster/qgspalettedrendererwidget.cpp b/src/gui/raster/qgspalettedrendererwidget.cpp
index bf2a695d357..9121619c6fb 100644
--- a/src/gui/raster/qgspalettedrendererwidget.cpp
+++ b/src/gui/raster/qgspalettedrendererwidget.cpp
@@ -583,7 +583,7 @@ QVariant QgsPalettedRendererModel::data( const QModelIndex &index, int role ) co
     }
 
     default:
-      return QVariant();
+      break;
   }
 
   return QVariant();
diff --git a/src/plugins/georeferencer/qgsimagewarper.cpp b/src/plugins/georeferencer/qgsimagewarper.cpp
index 7914932e1a9..0f8459f90f1 100644
--- a/src/plugins/georeferencer/qgsimagewarper.cpp
+++ b/src/plugins/georeferencer/qgsimagewarper.cpp
@@ -361,7 +361,7 @@ GDALResampleAlg QgsImageWarper::toGDALResampleAlg( const QgsImageWarper::Resampl
     case Lanczos:
       return GRA_Lanczos;
     default:
-      return GRA_NearestNeighbour;
+      break;
   };
 
   //avoid warning
diff --git a/src/providers/grass/qgis.v.in.cpp b/src/providers/grass/qgis.v.in.cpp
index 18976874968..dc663749f91 100644
--- a/src/providers/grass/qgis.v.in.cpp
+++ b/src/providers/grass/qgis.v.in.cpp
@@ -43,23 +43,23 @@ extern "C"
 #include "qgsgrass.h"
 #include "qgsgrassdatafile.h"
 
-static struct line_pnts *line = Vect_new_line_struct();
+static struct line_pnts *gLine = Vect_new_line_struct();
 
 void writePoint( struct Map_info *map, int type, const QgsPointXY &point, struct line_cats *cats )
 {
-  Vect_reset_line( line );
-  Vect_append_point( line, point.x(), point.y(), 0 );
-  Vect_write_line( map, type, line, cats );
+  Vect_reset_line( gLine );
+  Vect_append_point( gLine, point.x(), point.y(), 0 );
+  Vect_write_line( map, type, gLine, cats );
 }
 
 void writePolyline( struct Map_info *map, int type, const QgsPolyline &polyline, struct line_cats *cats )
 {
-  Vect_reset_line( line );
+  Vect_reset_line( gLine );
   Q_FOREACH ( const QgsPointXY &point, polyline )
   {
-    Vect_append_point( line, point.x(), point.y(), 0 );
+    Vect_append_point( gLine, point.x(), point.y(), 0 );
   }
-  Vect_write_line( map, type, line, cats );
+  Vect_write_line( map, type, gLine, cats );
 }
 
 static struct Map_info *finalMap = 0;
diff --git a/src/providers/oracle/ocispatial/qsql_ocispatial.cpp b/src/providers/oracle/ocispatial/qsql_ocispatial.cpp
index b128847e027..a5ae1a379aa 100644
--- a/src/providers/oracle/ocispatial/qsql_ocispatial.cpp
+++ b/src/providers/oracle/ocispatial/qsql_ocispatial.cpp
@@ -45,6 +45,16 @@
 #define QT_NO_DEBUG_OUTPUT
 #endif
 
+#if __cplusplus >= 201500
+#define FALLTHROUGH [[fallthrough]];
+#elif defined(__clang__)
+#define FALLTHROUGH //[[clang::fallthrough]]
+#elif defined(__GNUC__) && __GNUC__ >= 7
+#define FALLTHROUGH [[gnu::fallthrough]];
+#else
+#define FALLTHROUGH
+#endif
+
 #include "qsql_ocispatial.h"
 #include "wkbptr.h"
 
@@ -699,7 +709,10 @@ int QOCISpatialResultPrivate::bindValue( OCIStmt *sql, OCIBind **hbnd, OCIError
           setCharset( *hbnd, OCI_HTYPE_BIND );
         break;
       }
-    } // fall through for OUT values
+
+      FALLTHROUGH
+    }
+
     default:
     {
       const QString s = val.toString();
@@ -2006,6 +2019,9 @@ bool QOCISpatialCols::execBatch( QOCISpatialResultPrivate *d, QVector<QVariant>
               columns[i].lengths[row] = 0;
               break;
             }
+
+            FALLTHROUGH
+
           case QVariant::ByteArray:
           default:
           {
diff --git a/src/providers/postgres/qgspostgresexpressioncompiler.cpp b/src/providers/postgres/qgspostgresexpressioncompiler.cpp
index aa44dfd2b9a..41427aa6bc7 100644
--- a/src/providers/postgres/qgspostgresexpressioncompiler.cpp
+++ b/src/providers/postgres/qgspostgresexpressioncompiler.cpp
@@ -195,8 +195,8 @@ QgsSqlExpressionCompiler::Result QgsPostgresExpressionCompiler::compileNode( con
     }
 
     default:
-      return QgsSqlExpressionCompiler::compileNode( node, result );
+      break;
   }
 
-  return Fail;
+  return QgsSqlExpressionCompiler::compileNode( node, result );
 }
diff --git a/src/server/qgsconfigcache.h b/src/server/qgsconfigcache.h
index d5e599116e4..b2fafa2d011 100644
--- a/src/server/qgsconfigcache.h
+++ b/src/server/qgsconfigcache.h
@@ -29,10 +29,10 @@
 #include "qgis_server.h"
 #include "qgis_sip.h"
 #include "qgswmsconfigparser.h"
+#include "qgsproject.h"
 
 class QgsServerProjectParser;
 class QgsAccessControl;
-class QgsProject;
 
 class SERVER_EXPORT QgsConfigCache : public QObject
 {
diff --git a/tests/src/gui/CMakeLists.txt b/tests/src/gui/CMakeLists.txt
index 4552039787e..d93d898b845 100644
--- a/tests/src/gui/CMakeLists.txt
+++ b/tests/src/gui/CMakeLists.txt
@@ -75,13 +75,13 @@ INCLUDE_DIRECTORIES(SYSTEM
 #ENDIF (APPLE)
 
 SET(IMAGE_RCCS ../../../images/images.qrc)
-QT5_ADD_RESOURCES(IMAGE_RCC_SRCS ${IMAGE_RCCS})
 
 MACRO (ADD_QGIS_TEST testname testsrc)
   SET(qgis_${testname}_SRCS ${testsrc} ${util_SRCS})
   SET(qgis_${testname}_MOC_CPPS ${testsrc})
-  ADD_EXECUTABLE(qgis_${testname} ${qgis_${testname}_SRCS} ${IMAGE_RCC_SRCS})
+  ADD_EXECUTABLE(qgis_${testname} ${qgis_${testname}_SRCS} ${IMAGE_RCCS})
   SET_TARGET_PROPERTIES(qgis_${testname} PROPERTIES AUTOMOC TRUE)
+  SET_TARGET_PROPERTIES(qgis_${testname} PROPERTIES AUTORCC TRUE)
   TARGET_LINK_LIBRARIES(qgis_${testname}
     ${QT_QTXML_LIBRARY}
     ${QT_QTCORE_LIBRARY}