From 6f0ee6600d7dd97a16a37f33732b949f16fc06ba Mon Sep 17 00:00:00 2001
From: Artem Zhidkov <Artem.Zhidkov@opencascade.com>
Date: Fri, 5 Jun 2020 13:45:09 +0300
Subject: [PATCH] Issue #19187: B-Splines - Crash with specific scenario

Prohibit tangency constraint between B-spline curve and its control polygon.
---
 src/SketchPlugin/SketchPlugin_Validators.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/SketchPlugin/SketchPlugin_Validators.cpp b/src/SketchPlugin/SketchPlugin_Validators.cpp
index fbc98f205..f3543bc29 100644
--- a/src/SketchPlugin/SketchPlugin_Validators.cpp
+++ b/src/SketchPlugin/SketchPlugin_Validators.cpp
@@ -231,6 +231,9 @@ bool SketchPlugin_TangentAttrValidator::isValid(const AttributePtr& theAttribute
     std::set<FeaturePtr> aCoincidences = SketchPlugin_Tools::findCoincidentConstraints(aRefFea);
     for (std::set<FeaturePtr>::iterator anIt = aCoincidences.begin();
          anIt != aCoincidences.end() && !isValid; ++anIt) {
+      if ((*anIt)->getKind() == SketchPlugin_ConstraintCoincidenceInternal::ID())
+        continue; // skip internal constraints
+
       std::set<FeaturePtr> aCoinc;
       if (isApplicableCoincidence(*anIt, SketchPlugin_Constraint::ENTITY_A()))
         SketchPlugin_Tools::findCoincidences(*anIt, SketchPlugin_Constraint::ENTITY_B(),
-- 
2.39.2