Only emit OpEqual{Int,String} for simple types

Fixes #461

Author: antonmedv

compiler/compiler.go

@@ -360,16 +360,20 @@ func (c *compiler) BinaryNode(node *ast.BinaryNode) {
 	l := kind(node.Left)
 	r := kind(node.Right)
 
+	leftIsSimple := isSimpleType(node.Left)
+	rightIsSimple := isSimpleType(node.Right)
+	leftAndRightAreSimple := leftIsSimple && rightIsSimple
+
 	switch node.Operator {
 	case "==":
 		c.compile(node.Left)
 		c.derefInNeeded(node.Left)
 		c.compile(node.Right)
 		c.derefInNeeded(node.Left)
 
-		if l == r && l == reflect.Int {
+		if l == r && l == reflect.Int && leftAndRightAreSimple {
 			c.emit(OpEqualInt)
-		} else if l == r && l == reflect.String {
+		} else if l == r && l == reflect.String && leftAndRightAreSimple {
 			c.emit(OpEqualString)
 		} else {
 			c.emit(OpEqual)
@@ -534,6 +538,17 @@ func (c *compiler) BinaryNode(node *ast.BinaryNode) {
 	}
 }
 
+func isSimpleType(node ast.Node) bool {
+	if node == nil {
+		return false
+	}
+	t := node.Type()
+	if t == nil {
+		return false
+	}
+	return t.PkgPath() == ""
+}
+
 func (c *compiler) ChainNode(node *ast.ChainNode) {
 	c.chains = append(c.chains, []int{})
 	c.compile(node.Node)

expr_test.go

@@ -2022,3 +2022,83 @@ func TestIssue453(t *testing.T) {
 	_, err := expr.Compile(`foo()`, expr.Env(env))
 	require.Error(t, err)
 }
+
+func TestIssue461(t *testing.T) {
+	type EnvStr string
+	type EnvField struct {
+		S   EnvStr
+		Str string
+	}
+	type Env struct {
+		S        EnvStr
+		Str      string
+		EnvField EnvField
+	}
+	var tests = []struct {
+		input string
+		env   Env
+		want  bool
+	}{
+		{
+			input: "Str == S",
+			env:   Env{S: "string", Str: "string"},
+			want:  false,
+		},
+		{
+			input: "Str == Str",
+			env:   Env{Str: "string"},
+			want:  true,
+		},
+		{
+			input: "S == S",
+			env:   Env{Str: "string"},
+			want:  true,
+		},
+		{
+			input: `Str == "string"`,
+			env:   Env{Str: "string"},
+			want:  true,
+		},
+		{
+			input: `S == "string"`,
+			env:   Env{Str: "string"},
+			want:  false,
+		},
+		{
+			input: "EnvField.Str == EnvField.S",
+			env:   Env{EnvField: EnvField{S: "string", Str: "string"}},
+			want:  false,
+		},
+		{
+			input: "EnvField.Str == EnvField.Str",
+			env:   Env{EnvField: EnvField{Str: "string"}},
+			want:  true,
+		},
+		{
+			input: "EnvField.S == EnvField.S",
+			env:   Env{EnvField: EnvField{Str: "string"}},
+			want:  true,
+		},
+		{
+			input: `EnvField.Str == "string"`,
+			env:   Env{EnvField: EnvField{Str: "string"}},
+			want:  true,
+		},
+		{
+			input: `EnvField.S == "string"`,
+			env:   Env{EnvField: EnvField{Str: "string"}},
+			want:  false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			program, err := expr.Compile(tt.input, expr.Env(tt.env), expr.AsBool())
+
+			out, err := expr.Run(program, tt.env)
+			require.NoError(t, err)
+
+			require.Equal(t, tt.want, out)
+		})
+	}
+}