From 82f506e8e6706efa64a186f4feec98b143c4de3e Mon Sep 17 00:00:00 2001
From: Ben Paxton <ben.paxton@headforwards.com>
Date: Thu, 23 Feb 2017 12:06:29 +0000
Subject: [PATCH] Fix panic when eliding invalid constant cases

+, >, <, <=, and >= require typechecking of both operands
simultaneously; constant-operand eliding did not perform this check,
causing a panic.
---
 evaluationFailure_test.go | 12 ++++++++++++
 stagePlanner.go           |  4 ++++
 2 files changed, 16 insertions(+)

diff --git a/evaluationFailure_test.go b/evaluationFailure_test.go
index 9c947ab..6987771 100644
--- a/evaluationFailure_test.go
+++ b/evaluationFailure_test.go
@@ -96,6 +96,12 @@ func TestNilParameterUsage(test *testing.T) {
 func TestModifierTyping(test *testing.T) {
 
 	evaluationTests := []EvaluationFailureTest{
+		EvaluationFailureTest{
+
+			Name:     "PLUS literal number to literal bool",
+			Input:    "1 + true",
+			Expected: INVALID_MODIFIER_TYPES,
+		},
 		EvaluationFailureTest{
 
 			Name:     "PLUS number to bool",
@@ -242,6 +248,12 @@ func TestLogicalOperatorTyping(test *testing.T) {
 func TestComparatorTyping(test *testing.T) {
 
 	evaluationTests := []EvaluationFailureTest{
+		EvaluationFailureTest{
+
+			Name:     "GT literal bool to literal bool",
+			Input:    "true > true",
+			Expected: INVALID_COMPARATOR_TYPES,
+		},
 		EvaluationFailureTest{
 
 			Name:     "GT bool to bool",
diff --git a/stagePlanner.go b/stagePlanner.go
index 1a9f18d..3a87d48 100644
--- a/stagePlanner.go
+++ b/stagePlanner.go
@@ -658,6 +658,10 @@ func elideStage(root *evaluationStage) *evaluationStage {
 		return root
 	}
 
+	if root.typeCheck != nil && !root.typeCheck(leftValue, rightValue) {
+		return root
+	}
+
 	// pre-calculate, and return a new stage representing the result.
 	result, err = root.operator(leftValue, rightValue, nil)
 	if err != nil {