Merge pull request #1821 from openscad/issue1803

#1803: Fixed regression - intersections with difference child failed to preview correctly

src/csgnode.cc

@@ -181,6 +181,9 @@ void CSGProducts::import(shared_ptr<CSGNode> csgnode, OpenSCADOperator type, CSG
 		else if (type == OPENSCAD_DIFFERENCE) {
 			this->currentlist = &this->currentproduct->subtractions;
 		}
+		else if (type == OPENSCAD_INTERSECTION) {
+			this->currentlist = &this->currentproduct->intersections;
+		}
 		this->currentlist->push_back(CSGChainObject(leaf, newflags));
 	} else if (shared_ptr<CSGOperation> op = dynamic_pointer_cast<CSGOperation>(csgnode)) {
 		assert(op->left() && op->right());

testdata/scad/bugs/issue1803.scad

@@ -0,0 +1,10 @@
+$fn=32;
+
+intersection(){
+    difference(){
+        cube(size=50, center=true);
+        cylinder(d=30,h=80, center=true);
+    }
+    cylinder(d=65,h=80,center=true);
+    rotate([90,0,0]) cylinder(d=65,h=80,center=true);
+}

tests/CMakeLists.txt

@@ -1415,6 +1415,7 @@ list(APPEND BUGS_FILES ${CMAKE_SOURCE_DIR}/../testdata/scad/bugs/issue13.scad
                        ${CMAKE_SOURCE_DIR}/../testdata/scad/bugs/issue1580-import-back-to-back2.scad
                        ${CMAKE_SOURCE_DIR}/../testdata/scad/bugs/issue1580-zero-area-triangle.scad
                        ${CMAKE_SOURCE_DIR}/../testdata/scad/bugs/issue1580-import-zero-area-triangle.scad
+                       ${CMAKE_SOURCE_DIR}/../testdata/scad/bugs/issue1803.scad
 )
 
 # We know that we cannot import weakly manifold files into CGAL, so to make tests easier