Avoid Coverity unchecked return value warnings

src/app/qgsattributetabledialog.cpp

@@ -510,7 +510,7 @@ void QgsAttributeTableDialog::runFieldCalculation( QgsVectorLayer *layer, const
     context.lastScope()->addVariable( QgsExpressionContextScope::StaticVariable( QStringLiteral( "row_number" ), rownum, true ) );
 
     QVariant value = exp.evaluate( &context );
-    fld.convertCompatible( value );
+    ( void )fld.convertCompatible( value );
     // Bail if we have a update error
     if ( exp.hasEvalError() )
     {

src/app/qgsfieldcalculator.cpp

@@ -299,7 +299,7 @@ void QgsFieldCalculator::accept()
       }
       else
       {
-        field.convertCompatible( value );
+        ( void )field.convertCompatible( value );
         mVectorLayer->changeAttributeValue( feature.id(), mAttributeId, value, newField ? emptyAttribute : feature.attributes().value( mAttributeId ) );
       }
 

src/core/qgsvectorlayerfeatureiterator.cpp

@@ -875,7 +875,7 @@ void QgsVectorLayerFeatureIterator::addExpressionAttribute( QgsFeature &f, int a
   {
     mExpressionContext->setFeature( f );
     QVariant val = exp->evaluate( mExpressionContext.get() );
-    mSource->mFields.at( attrIndex ).convertCompatible( val );
+    ( void )mSource->mFields.at( attrIndex ).convertCompatible( val );
     f.setAttribute( attrIndex, val );
   }
   else

src/gui/editorwidgets/qgsrangewidgetwrapper.cpp

@@ -141,9 +141,9 @@ void QgsRangeWidgetWrapper::initWidget( QWidget *editor )
   }
   else
   {
-    field().convertCompatible( min );
-    field().convertCompatible( max );
-    field().convertCompatible( step );
+    ( void )field().convertCompatible( min );
+    ( void )field().convertCompatible( max );
+    ( void )field().convertCompatible( step );
     if ( mQgsDial ) setupIntEditor( min, max, step, mQgsDial, this );
     else if ( mQgsSlider ) setupIntEditor( min, max, step, mQgsSlider, this );
     else if ( mDial ) setupIntEditor( min, max, step, mDial, this );

tests/src/core/testqgslayoutmodel.cpp

@@ -789,7 +789,7 @@ void TestQgsLayoutModel::proxyCrash()
   layout->addLayoutItem( item3 );
 
   // reorder items - expect no crash!
-  layout->itemsModel()->reorderItemUp( item1 );
+  ( void )layout->itemsModel()->reorderItemUp( item1 );
 }
 
 QGSTEST_MAIN( TestQgsLayoutModel )