cgen: fix mut map with relation op in fn (#5642)

vlib/builtin/map_test.v

@@ -313,3 +313,35 @@ fn test_map_in_mut() {
 	map_in_mut(mut m)
 	assert m['one'] == 2
 }
+
+fn mut_map_with_relation_op_in_fn(mut m map[string]int) {
+	if m['one'] == 1 {
+		m['three'] = 3
+	}
+	if m['two'] != 1 {
+		m['four'] = 4	
+	}
+	if m['one'] > 0 {
+		m['five'] = 5	
+	}
+	if m['one'] < 2 {
+		m['six'] = 6	
+	}
+	if m['two'] >= 2 {
+		m['seven'] = 7	
+	}
+	if m['two'] <= 2 {
+		m['eight'] = 8	
+	}
+}
+
+fn test_mut_map_with_relation_op_in_fn() {
+	mut m := {'one':1, 'two':2}
+	mut_map_with_relation_op_in_fn(mut m)
+	assert 'three' in m
+	assert 'four' in m
+	assert 'five' in m
+	assert 'six' in m
+	assert 'seven' in m
+	assert 'eight' in m
+}

vlib/v/gen/cgen.v

@@ -2360,6 +2360,9 @@ fn (mut g Gen) index_expr(node ast.IndexExpr) {
 				} else {
 					zero := g.type_default(info.value_type)
 					g.write('(*($elem_type_str*)map_get(')
+					if node.left_type.is_ptr() {
+						g.write('*')
+					}
 					g.expr(node.left)
 					g.write(', ')
 					g.expr(node.index)