add test (closes #4742)

tests/misc/projects/Issue4742/Main.hx

@@ -0,0 +1,6 @@
+class Main {
+    static function main() {
+        f("Haxe is great!") + "abc"; // This must produce a error!
+    }
+    static function f(s) : Void trace(s);
+}

tests/misc/projects/Issue4742/compile-fail.hxml

@@ -0,0 +1,3 @@
+-main Main
+-neko neko.n
+--no-output

tests/misc/projects/Issue4742/compile-fail.hxml.stderr

@@ -0,0 +1 @@
+Main.hx:3: characters 8-27 : Cannot use Void as value