From f1f75683c1014769f268c739e8af6c75773ece99 Mon Sep 17 00:00:00 2001
From: Mike Farah <mikefarah@gmail.com>
Date: Fri, 28 May 2021 16:59:02 +1000
Subject: [PATCH] Fixed nil RHS bug in alternative operator #838

---
 pkg/yqlib/operator_alternative_test.go | 6 ++++++
 pkg/yqlib/operator_booleans_test.go    | 8 ++++++++
 pkg/yqlib/operator_equals_test.go      | 7 +++++++
 pkg/yqlib/operators.go                 | 8 ++++++--
 4 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/pkg/yqlib/operator_alternative_test.go b/pkg/yqlib/operator_alternative_test.go
index 902fe17..9a57a05 100644
--- a/pkg/yqlib/operator_alternative_test.go
+++ b/pkg/yqlib/operator_alternative_test.go
@@ -5,6 +5,12 @@ import (
 )
 
 var alternativeOperatorScenarios = []expressionScenario{
+	{
+		skipDoc:    true,
+		expression: `.b // .c`,
+		document:   `a: bridge`,
+		expected:   []string{},
+	},
 	{
 		skipDoc:    true,
 		expression: `(.b // "hello") as $x`,
diff --git a/pkg/yqlib/operator_booleans_test.go b/pkg/yqlib/operator_booleans_test.go
index d94eee5..2f3477d 100644
--- a/pkg/yqlib/operator_booleans_test.go
+++ b/pkg/yqlib/operator_booleans_test.go
@@ -12,6 +12,14 @@ var booleanOperatorScenarios = []expressionScenario{
 			"D0, P[], (!!bool)::true\n",
 		},
 	},
+	{
+		skipDoc:    true,
+		document:   "b: hi",
+		expression: `.a or .c`,
+		expected: []string{
+			"D0, P[], (!!bool)::false\n",
+		},
+	},
 	{
 		skipDoc:    true,
 		document:   "b: hi",
diff --git a/pkg/yqlib/operator_equals_test.go b/pkg/yqlib/operator_equals_test.go
index 07cd3cf..e815f89 100644
--- a/pkg/yqlib/operator_equals_test.go
+++ b/pkg/yqlib/operator_equals_test.go
@@ -5,6 +5,13 @@ import (
 )
 
 var equalsOperatorScenarios = []expressionScenario{
+	{
+		skipDoc:    true,
+		expression: ".a == .b",
+		expected: []string{
+			"D0, P[], (!!bool)::true\n",
+		},
+	},
 	{
 		skipDoc:    true,
 		document:   "cat",
diff --git a/pkg/yqlib/operators.go b/pkg/yqlib/operators.go
index 1242b6f..1b0731d 100644
--- a/pkg/yqlib/operators.go
+++ b/pkg/yqlib/operators.go
@@ -31,7 +31,9 @@ func resultsForRhs(d *dataTreeNavigator, context Context, lhsCandidate *Candidat
 		if err != nil {
 			return err
 		}
-		results.PushBack(resultCandidate)
+		if resultCandidate != nil {
+			results.PushBack(resultCandidate)
+		}
 		return nil
 	}
 
@@ -42,7 +44,9 @@ func resultsForRhs(d *dataTreeNavigator, context Context, lhsCandidate *Candidat
 		if err != nil {
 			return err
 		}
-		results.PushBack(resultCandidate)
+		if resultCandidate != nil {
+			results.PushBack(resultCandidate)
+		}
 	}
 	return nil
 }