Polygon from QgsPoints - QGIS 3.8 python

Question

I'm trying to create a polygon layer from 4 points that I have already defined. There issue here is that I'm always getting the following error:

AttributeError: type object 'QgsGeometry' has no attribute 'fromPolygon'

These are the points (printed in console):

print (points)
<QgsPoint: Point (546016.50083752069622278 4760165.85990538075566292)>
<QgsPoint: Point (535433.25716883409768343 4749582.61623669415712357)>
<QgsPoint: Point (559882.5150161839555949 4746299.84572671726346016)>
<QgsPoint: Point (549299.27134749735705554 4735716.60205803066492081)>

And here is the code that produces the error above:

layer = QgsVectorLayer(str('Polygon?crs='+crs), 'polygon' , 'memory')
prov = layer.dataProvider()
points = [H1V1p,H1V2p,H2V1p,H2V2p]
feat = QgsFeature()
feat.setGeometry(QgsGeometry.fromPolygon([points]))
prov.addFeatures([feat])
layer.updateExtents()
QgsMapLayerRegistry.instance().addMapLayers([layer])

Answer 1

In the line of the @BERA comment, this solves the problem in QGIS 3.8:

The points must be created with 'QgsPointXY' (instead of 'QgsPoint').

The polygon must be created with 'fromPolygonXY' (instead of fromPolygon').

p1 = QgsPointXY(546016, 4760165)
p2 = QgsPointXY(535433, 4749582)
p3 = QgsPointXY(535833, 4749982)

layer = QgsVectorLayer('Polygon', 'polygon' , 'memory')
prov = layer.dataProvider()
points = [p1,p2,p3]
feat = QgsFeature()
feat.setGeometry(QgsGeometry.fromPolygonXY([points]))
prov.addFeatures([feat])
layer.updateExtents()
QgsMapLayerRegistry.instance().addMapLayers([layer])