From 7c79c70890e059acfb95d334ca9ae0fcfb314aec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89milie=20Feral?= <emilie.feral@numworks.com>
Date: Tue, 24 Mar 2020 12:16:05 +0100
Subject: [PATCH] [poincare] When simplification has been interrupted, escape
 the end of simplification. Otherwise we can be stuck in infinite loop.
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This fixes the following bug: when simplifying an expression as
'bigRational1^x*bigRational2^x', we use the rule a^x*b^x --> (a¨b)^x. However,
in this case, a*b can't be reduce (resulting rational would be too big) and
we're stuck in the loop a^x*b^x --> (a¨b)^x --> a^x*b^x --> (a¨b)^x...
---
 poincare/src/expression.cpp      | 28 ++++++++++++++++------------
 poincare/test/simplification.cpp |  2 ++
 2 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/poincare/src/expression.cpp b/poincare/src/expression.cpp
index 602bd3663..7f9c761d8 100644
--- a/poincare/src/expression.cpp
+++ b/poincare/src/expression.cpp
@@ -321,18 +321,22 @@ void Expression::defaultDeepReduceChildren(ExpressionNode::ReductionContext redu
 
 Expression Expression::defaultShallowReduce() {
   Expression result;
-  const int childrenCount = numberOfChildren();
-  for (int i = 0; i < childrenCount; i++) {
-    /* The reduction is shortcut if one child is unreal or undefined:
-     * - the result is unreal if at least one child is unreal
-     * - the result is undefined if at least one child is undefined but no child
-     *   is unreal */
-    ExpressionNode::Type childIType = childAtIndex(i).type();
-    if (childIType == ExpressionNode::Type::Unreal) {
-      result = Unreal::Builder();
-      break;
-    } else if (childIType == ExpressionNode::Type::Undefined) {
-      result = Undefined::Builder();
+  if (sSimplificationHasBeenInterrupted) {
+    result = Undefined::Builder();
+  } else {
+    const int childrenCount = numberOfChildren();
+    for (int i = 0; i < childrenCount; i++) {
+      /* The reduction is shortcut if one child is unreal or undefined:
+       * - the result is unreal if at least one child is unreal
+       * - the result is undefined if at least one child is undefined but no child
+       *   is unreal */
+      ExpressionNode::Type childIType = childAtIndex(i).type();
+      if (childIType == ExpressionNode::Type::Unreal) {
+        result = Unreal::Builder();
+        break;
+      } else if (childIType == ExpressionNode::Type::Undefined) {
+        result = Undefined::Builder();
+      }
     }
   }
   if (!result.isUninitialized()) {
diff --git a/poincare/test/simplification.cpp b/poincare/test/simplification.cpp
index cd5bd1c04..89eb2c287 100644
--- a/poincare/test/simplification.cpp
+++ b/poincare/test/simplification.cpp
@@ -1317,6 +1317,8 @@ QUIZ_CASE(poincare_simplification_mix) {
   //assert_parsed_expression_simplify_to("log(cos(9)^ln(6), 9)", "ln(6)×log(cos(9), 9)"); // TODO: for this to work, we must know the sign of cos(9)
   assert_parsed_expression_simplify_to("(((√(6)-√(2))/4)/((√(6)+√(2))/4))+1", "-√(3)+3");
   assert_parsed_expression_simplify_to("1/√(𝐢) × (√(2)-𝐢×√(2))", "-2×𝐢"); // TODO: get rid of complex at denominator?
+
+  assert_expression_simplifies_approximates_to<double>("abs(√(300000.0003^23))", "9.7027409010183ᴇ62");
 }
 
 QUIZ_CASE(poincare_hyperbolic_trigonometry) {