From 742c4385220e510a108b776d36af3c8570fdbc1d Mon Sep 17 00:00:00 2001
From: Anton Medvedev <anton@medv.io>
Date: Wed, 22 Feb 2023 23:56:44 +0100
Subject: [PATCH] Fix builtins checks for nil args

---
 builtin/builtin.go      | 15 +++++++++++----
 checker/checker_test.go | 18 ++++++++++++++++++
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/builtin/builtin.go b/builtin/builtin.go
index 4ea819a7f..ad9376962 100644
--- a/builtin/builtin.go
+++ b/builtin/builtin.go
@@ -34,7 +34,7 @@ var Builtins = map[int]*Function{
 			if len(args) != 1 {
 				return anyType, fmt.Errorf("invalid number of arguments for len (expected 1, got %d)", len(args))
 			}
-			switch args[0].Kind() {
+			switch kind(args[0]) {
 			case reflect.Array, reflect.Map, reflect.Slice, reflect.String, reflect.Interface:
 				return integerType, nil
 			}
@@ -48,7 +48,7 @@ var Builtins = map[int]*Function{
 			if len(args) != 1 {
 				return anyType, fmt.Errorf("invalid number of arguments for abs (expected 1, got %d)", len(args))
 			}
-			switch args[0].Kind() {
+			switch kind(args[0]) {
 			case reflect.Float32, reflect.Float64, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Interface:
 				return args[0], nil
 			}
@@ -62,7 +62,7 @@ var Builtins = map[int]*Function{
 			if len(args) != 1 {
 				return anyType, fmt.Errorf("invalid number of arguments for int (expected 1, got %d)", len(args))
 			}
-			switch args[0].Kind() {
+			switch kind(args[0]) {
 			case reflect.Interface:
 				return integerType, nil
 			case reflect.Float32, reflect.Float64, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
@@ -80,7 +80,7 @@ var Builtins = map[int]*Function{
 			if len(args) != 1 {
 				return anyType, fmt.Errorf("invalid number of arguments for float (expected 1, got %d)", len(args))
 			}
-			switch args[0].Kind() {
+			switch kind(args[0]) {
 			case reflect.Interface:
 				return floatType, nil
 			case reflect.Float32, reflect.Float64, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
@@ -92,3 +92,10 @@ var Builtins = map[int]*Function{
 		},
 	},
 }
+
+func kind(t reflect.Type) reflect.Kind {
+	if t == nil {
+		return reflect.Invalid
+	}
+	return t.Kind()
+}
diff --git a/checker/checker_test.go b/checker/checker_test.go
index ba612a4c4..eba6a1f81 100644
--- a/checker/checker_test.go
+++ b/checker/checker_test.go
@@ -875,3 +875,21 @@ func TestCheck_Function_without_types(t *testing.T) {
 	require.NotNil(t, tree.Node.(*ast.CallNode).Func)
 	require.Equal(t, "add", tree.Node.(*ast.CallNode).Func.Name)
 }
+
+func TestCheck_dont_panic_on_nil_arguments_for_builtins(t *testing.T) {
+	tests := []string{
+		"len(nil)",
+		"abs(nil)",
+		"int(nil)",
+		"float(nil)",
+	}
+	for _, test := range tests {
+		t.Run(test, func(t *testing.T) {
+			tree, err := parser.Parse(test)
+			require.NoError(t, err)
+
+			_, err = checker.Check(tree, conf.New(nil))
+			require.Error(t, err)
+		})
+	}
+}