Resolve function parameter types by checking calls to the function

UpsilonTests/FunctionTests.cs

@@ -52,17 +52,34 @@ testFunc(100)
         {
             const string input = @"
 function testFunc (var1)
-    b = var1 == true
+    var1 == true
 end
 testFunc(100)
 ";
             var script = new Script(input);
             Assert.Empty(script.Diagnostics.Messages);
             script.Evaluate();
-            Assert.Empty(script.Diagnostics.Messages);
+            Assert.Single(script.Diagnostics.Messages);
             Assert.True(script.Scope.TryGet("testFunc", out var func));
             Assert.IsType<LuaFunction>(func);
         }
 
+        [Fact]
+        public void BindUnusedFunctions()
+        {
+            const string input = @"
+function testFunc (var1)
+    var1 == true
+end
+";
+            var script = new Script(input);
+            Assert.Empty(script.Diagnostics.Messages);
+            script.Evaluate();
+            Assert.Empty(script.Diagnostics.Messages);
+            Assert.True(script.Scope.TryGet("testFunc", out var func));
+            var castType = Assert.IsType<LuaFunction>(func);
+            Assert.NotNull(castType.Block);
+        }
+
     }
 }