HLSL: Error if funcion with return type doesn't return a value.

Test/hlsl.void.frag

@@ -1,8 +1,9 @@
 void foo1() {}
 void foo2(void) {}
 
-float4 PixelShaderFunction(float4 input) : COLOR0
+void PixelShaderFunction(float4 input) : COLOR0
 {
     foo1();
     foo2();
+    return;
 }