Graph Editor: loading material with invalid connections / type mismatches

[marwie]

Hi,

again codegen produced some invalid MaterialX code where we connect a color4 node to a color3 output.

The GraphView happily displays this connection when opening the file

I'm only getting an error when trying to pipe the output then into the shader

Problematic material:

<?xml version="1.0"?>
<materialx name="" version="1.38" >
	<nodegraph name="needle_shadergraph" >
		<input name="_MyColor" type="color4" value="0.8962264, 0.2494215, 0.2494215, 1.0" />
		<constant name="_MyColor_constant" type="color4" >
			<input name="value" type="color4" interfacename="_MyColor" />
		</constant>
		<output name="_MyColor_constant_out" type="color3" nodename="_MyColor_constant" />
	</nodegraph>
	<standard_surface name="needle_standard_surface" type="surfaceshader" >
		<input name="base_color" type="color3" nodename="_MyColor_constant_out" />
		<input name="specular_roughness" type="float" value="1.0" />
		<input name="metalness" type="float" value="1.0" />
	</standard_surface>
	<surfacematerial name="Default" type="material" >
		<input name="surfaceshader" type="surfaceshader" nodename="needle_standard_surface" />
	</surfacematerial>
</materialx>

Also attaching a video illustrating the issue note that the invalid connection is correctly refused in the UI when trying to do it but not when loading the graph also note that when I connect the subgraph output to the shader we get compiler errors and rendering breaks due to the type mismatch

https://github.com/AcademySoftwareFoundation/MaterialX/assets/5083203/62136046-aa6e-4142-b01c-cfd0ef7380e3