From 01c358d5eb221201013d8b85f230960e2b5dd019 Mon Sep 17 00:00:00 2001
From: Anton Medvedev <anton@medv.io>
Date: Wed, 6 Sep 2023 10:36:40 +0200
Subject: [PATCH] Fix type checker for "in" operator

Fixes #426
---
 checker/checker.go      | 13 ++-----------
 checker/checker_test.go |  5 +++++
 checker/types.go        | 15 +++++++++++++++
 expr_test.go            |  8 ++++++++
 4 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/checker/checker.go b/checker/checker.go
index 287164b64..3e787fa4f 100644
--- a/checker/checker.go
+++ b/checker/checker.go
@@ -242,16 +242,7 @@ func (v *checker) BinaryNode(node *ast.BinaryNode) (reflect.Type, info) {
 
 	switch node.Operator {
 	case "==", "!=":
-		if isNumber(l) && isNumber(r) {
-			return boolType, info{}
-		}
-		if l == nil || r == nil { // It is possible to compare with nil.
-			return boolType, info{}
-		}
-		if l.Kind() == r.Kind() {
-			return boolType, info{}
-		}
-		if isAny(l) || isAny(r) {
+		if isComparable(l, r) {
 			return boolType, info{}
 		}
 
@@ -357,7 +348,7 @@ func (v *checker) BinaryNode(node *ast.BinaryNode) (reflect.Type, info) {
 			if l == nil { // It is possible to compare with nil.
 				return boolType, info{}
 			}
-			if !isAny(l) && !l.AssignableTo(r.Elem()) && !(isInteger(l) && isInteger(r.Elem())) {
+			if !isComparable(l, r.Elem()) {
 				return v.error(node, "cannot use %v as type %v in array", l, r.Elem())
 			}
 			return boolType, info{}
diff --git a/checker/checker_test.go b/checker/checker_test.go
index 69c0a8e76..7528f1da9 100644
--- a/checker/checker_test.go
+++ b/checker/checker_test.go
@@ -513,6 +513,11 @@ cannot use float64 as type int in map key (1:5)
  | 1/2 in MapIntAny
  | ....^
 
+0.5 in ArrayOfFoo
+cannot use float64 as type *mock.Foo in array (1:5)
+ | 0.5 in ArrayOfFoo
+ | ....^
+
 repeat("0", 1/0)
 cannot use float64 as argument (type int) to call repeat  (1:14)
  | repeat("0", 1/0)
diff --git a/checker/types.go b/checker/types.go
index 1665527f0..890d74a5f 100644
--- a/checker/types.go
+++ b/checker/types.go
@@ -227,3 +227,18 @@ func kind(t reflect.Type) reflect.Kind {
 	}
 	return t.Kind()
 }
+
+func isComparable(l, r reflect.Type) bool {
+	if l == nil || r == nil {
+		return true
+	}
+	switch {
+	case l.Kind() == r.Kind():
+		return true
+	case isNumber(l) && isNumber(r):
+		return true
+	case isAny(l) || isAny(r):
+		return true
+	}
+	return false
+}
diff --git a/expr_test.go b/expr_test.go
index 84d31bf9e..1857403ec 100644
--- a/expr_test.go
+++ b/expr_test.go
@@ -1084,6 +1084,14 @@ func TestExpr(t *testing.T) {
 			`4/2 == 2`,
 			true,
 		},
+		{
+			`.5 in 0..1`,
+			false,
+		},
+		{
+			`.5 in ArrayOfInt`,
+			false,
+		},
 	}
 
 	for _, tt := range tests {