From cedda5ef4f73fccfc795e6bc48b368e48f11ad8d Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Wed, 10 Jan 2018 11:48:06 -0800
Subject: [PATCH] [core] Handle NaN input to interpolate and step

---
 include/mbgl/style/expression/interpolate.hpp | 12 +++++++++---
 platform/node/test/ignores.json               |  1 -
 src/mbgl/style/expression/step.cpp            |  9 ++++++++-
 src/mbgl/style/expression/value.cpp           | 10 +++-------
 4 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/include/mbgl/style/expression/interpolate.hpp b/include/mbgl/style/expression/interpolate.hpp
index 439122f91..fd9ec25a2 100644
--- a/include/mbgl/style/expression/interpolate.hpp
+++ b/include/mbgl/style/expression/interpolate.hpp
@@ -11,7 +11,7 @@
 
 #include <memory>
 #include <map>
-
+#include <cmath>
 
 namespace mbgl {
 namespace style {
@@ -109,9 +109,15 @@ public:
     
     EvaluationResult evaluate(const EvaluationContext& params) const override {
         const EvaluationResult evaluatedInput = input->evaluate(params);
-        if (!evaluatedInput) { return evaluatedInput.error(); }
+        if (!evaluatedInput) {
+            return evaluatedInput.error();
+        }
+
         float x = *fromExpressionValue<float>(*evaluatedInput);
-        
+        if (std::isnan(x)) {
+            return EvaluationError { "Input is not a number." };
+        }
+
         if (stops.empty()) {
             return EvaluationError { "No stops in exponential curve." };
         }
diff --git a/platform/node/test/ignores.json b/platform/node/test/ignores.json
index 7cb3560f4..3f904c304 100644
--- a/platform/node/test/ignores.json
+++ b/platform/node/test/ignores.json
@@ -50,7 +50,6 @@
   "render-tests/regressions/mapbox-gl-js#2762": "https://github.com/mapbox/mapbox-gl-native/issues/10619",
   "render-tests/regressions/mapbox-gl-js#2769": "https://github.com/mapbox/mapbox-gl-native/issues/10619",
   "render-tests/regressions/mapbox-gl-js#3682": "https://github.com/mapbox/mapbox-gl-js/issues/3682",
-  "render-tests/regressions/mapbox-gl-js#4172": "https://github.com/mapbox/mapbox-gl-native/issues/10618",
   "render-tests/regressions/mapbox-gl-js#5370": "skip - https://github.com/mapbox/mapbox-gl-native/pull/9439",
   "render-tests/regressions/mapbox-gl-js#5599": "https://github.com/mapbox/mapbox-gl-native/issues/10399",
   "render-tests/regressions/mapbox-gl-js#5740": "https://github.com/mapbox/mapbox-gl-native/issues/10619",
diff --git a/src/mbgl/style/expression/step.cpp b/src/mbgl/style/expression/step.cpp
index bfcb6fd27..11bf543b7 100644
--- a/src/mbgl/style/expression/step.cpp
+++ b/src/mbgl/style/expression/step.cpp
@@ -2,6 +2,7 @@
 #include <mbgl/style/expression/get_covering_stops.hpp>
 #include <mbgl/util/string.hpp>
 
+#include <cmath>
 
 namespace mbgl {
 namespace style {
@@ -9,8 +10,14 @@ namespace expression {
 
 EvaluationResult Step::evaluate(const EvaluationContext& params) const {
     const EvaluationResult evaluatedInput = input->evaluate(params);
-    if (!evaluatedInput) { return evaluatedInput.error(); }
+    if (!evaluatedInput) {
+        return evaluatedInput.error();
+    }
+
     float x = *fromExpressionValue<float>(*evaluatedInput);
+    if (std::isnan(x)) {
+        return EvaluationError { "Input is not a number." };
+    }
 
     if (stops.empty()) {
         return EvaluationError { "No stops in step curve." };
diff --git a/src/mbgl/style/expression/value.cpp b/src/mbgl/style/expression/value.cpp
index b75f471ce..ef4769df0 100644
--- a/src/mbgl/style/expression/value.cpp
+++ b/src/mbgl/style/expression/value.cpp
@@ -108,13 +108,9 @@ Value ValueConverter<float>::toExpressionValue(const float value) {
 }
 
 optional<float> ValueConverter<float>::fromExpressionValue(const Value& value) {
-    if (value.template is<double>()) {
-        double v = value.template get<double>();
-        if (v <= std::numeric_limits<float>::max()) {
-            return static_cast<float>(v);
-        }
-    }
-    return optional<float>();
+    return value.template is<double>()
+        ? static_cast<float>(value.template get<double>())
+        : optional<float>();
 }