From f3628f368f9c28d149a88ae740c74b8f952f7344 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=C3=A9a=20Saviot?= <lea.saviot@numworks.com>
Date: Tue, 28 Jul 2020 17:07:22 +0200
Subject: [PATCH] [poincare/expression] Return undef if simplification
 interrupted

Without this change, we would get weird "reduced" expression, such as
multiplication(undef, _s), but we do not always check
sSimplificationHasBeenInterrupted afterwards.
---
 poincare/src/expression.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/poincare/src/expression.cpp b/poincare/src/expression.cpp
index 756ddd69a..f9b066832 100644
--- a/poincare/src/expression.cpp
+++ b/poincare/src/expression.cpp
@@ -817,7 +817,11 @@ Expression Expression::angleUnitToRadian(Preferences::AngleUnit angleUnit) {
 
 Expression Expression::reduce(ExpressionNode::ReductionContext reductionContext) {
   sSimplificationHasBeenInterrupted = false;
-  return deepReduce(reductionContext);
+  Expression result = deepReduce(reductionContext);
+  if (sSimplificationHasBeenInterrupted) {
+    return replaceWithUndefinedInPlace();
+  }
+  return result;
 }
 
 Expression Expression::deepReduce(ExpressionNode::ReductionContext reductionContext) {