Commit c1ef019d35 moved splitSelfTouchingOutlines() into
cacheTriangulation(), placing it before Fracture(). When a polygon
has holes, splitSelfTouchingOutlines() splits the outer boundary but
the new sub-polygon inherits no holes. Its triangulation then spans
the knockout areas, producing false DRC clearance violations.
Fix the order: call Fracture() first so holes are merged into the
outline, then call splitSelfTouchingOutlines().
After Fracture(), Clipper2 rounds corridor-cut vertices to integer
coordinates; they can land within 1nm of a segment endpoint.
SEG::Contains() accepts points within sqrt(3) nm as on-segment, so
those vertices trigger false pinch-point splits. Use SquaredDistance()
== 0, which requires exact coincidence, to detect only true pinch
points.
Fixes https://gitlab.com/kicad/code/kicad/issues/23123
Seth Hillbrand
8818f79dcf