From 85baef0b4957b69357227a47dae530599c10c1bf Mon Sep 17 00:00:00 2001
From: schillic <git@christianschilling.net>
Date: Fri, 20 Dec 2024 21:51:53 +0100
Subject: [PATCH] make 'tohrep' of 'VPolgyon' type stable

---
 src/Sets/VPolygon/VPolygonModule.jl | 5 +++--
 src/Sets/VPolygon/tohrep.jl         | 2 +-
 test/Sets/Polygon.jl                | 3 ++-
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/Sets/VPolygon/VPolygonModule.jl b/src/Sets/VPolygon/VPolygonModule.jl
index d31f48f3d7..6f5bb2d441 100644
--- a/src/Sets/VPolygon/VPolygonModule.jl
+++ b/src/Sets/VPolygon/VPolygonModule.jl
@@ -4,8 +4,9 @@ using Reexport, Requires
 
 using ..LazySets: AbstractPolygon, LazySet, AbstractHPolygon, halfspace_left,
                   is_right_turn, _area_vlist, _extrema_vlist, _high_vlist,
-                  _intersection_vrep_2d, _linear_map_vrep, _low_vlist,
-                  _minkowski_sum_vrep_2d, _to_colVector
+                  _infeasible_constraints_list, _intersection_vrep_2d,
+                  _linear_map_vrep, _low_vlist, _minkowski_sum_vrep_2d,
+                  _to_colVector
 using ..HPolygonModule: HPolygon
 using LinearAlgebra: dot
 using Random: AbstractRNG, GLOBAL_RNG, shuffle
diff --git a/src/Sets/VPolygon/tohrep.jl b/src/Sets/VPolygon/tohrep.jl
index 6125e6022c..9df5cd46af 100644
--- a/src/Sets/VPolygon/tohrep.jl
+++ b/src/Sets/VPolygon/tohrep.jl
@@ -24,7 +24,7 @@ function tohrep(P::VPolygon{N}, ::Type{HPOLYGON}=HPolygon) where {N,HPOLYGON<:Ab
     n = length(vl)
     if n == 0
         # no vertex
-        return EmptySet{N}(2)
+        constraints_list = _infeasible_constraints_list(2; N=N)
     elseif n == 1
         # only one vertex -> use function for singletons
         require(@__MODULE__, :LazySets; fun_name="convert")
diff --git a/test/Sets/Polygon.jl b/test/Sets/Polygon.jl
index 5997fdf302..82700b1dbd 100644
--- a/test/Sets/Polygon.jl
+++ b/test/Sets/Polygon.jl
@@ -460,7 +460,8 @@ for N in [Float64, Float32, Rational{Int}]
     end
 
     # empty VPolygon: conversion to hrep
-    @test tohrep(VPolygon{N}()) isa EmptySet{N}
+    P = tohrep(VPolygon{N}())
+    @test P isa HPolygon{N} && isempty(P)
 
     # test VPolygon constructor given the matrix of vertices
     m = N[4 0; 6 2; 4 4]'