Fix T99104: EEVEE: Regression: Crash when using Light Output in Materials

Using Light output is supported in Cycles. This patch adds support for it
and remove the crash in `ntree_shader_weight_tree_invert()` by treating
it as any other outputs.

Candidate for 3.2.1 corrective release.

source/blender/nodes/shader/node_shader_tree.cc

@@ -712,6 +712,7 @@ static void ntree_shader_weight_tree_invert(bNodeTree *ntree, bNode *output_node
 
       switch (node->type) {
         case SH_NODE_SHADERTORGB:
+        case SH_NODE_OUTPUT_LIGHT:
         case SH_NODE_OUTPUT_WORLD:
         case SH_NODE_OUTPUT_MATERIAL: {
           /* Start the tree with full weight. */
@@ -810,6 +811,7 @@ static void ntree_shader_weight_tree_invert(bNodeTree *ntree, bNode *output_node
 
         switch (node->type) {
           case SH_NODE_SHADERTORGB:
+          case SH_NODE_OUTPUT_LIGHT:
           case SH_NODE_OUTPUT_WORLD:
           case SH_NODE_OUTPUT_MATERIAL:
           case SH_NODE_ADD_SHADER: {

source/blender/nodes/shader/nodes/node_shader_output_light.cc

@@ -10,6 +10,22 @@ static void node_declare(NodeDeclarationBuilder &b)
   b.add_input<decl::Shader>(N_("Surface"));
 }
 
+static int node_shader_gpu_output_light(GPUMaterial *mat,
+                                        bNode *UNUSED(node),
+                                        bNodeExecData *UNUSED(execdata),
+                                        GPUNodeStack *in,
+                                        GPUNodeStack *UNUSED(out))
+{
+  GPUNodeLink *outlink_surface;
+  /* Passthrough node in order to do the right socket conversions. */
+  if (in[0].link) {
+    /* Reuse material output. */
+    GPU_link(mat, "node_output_material_surface", in[0].link, &outlink_surface);
+    GPU_material_output_surface(mat, outlink_surface);
+  }
+  return true;
+}
+
 }  // namespace blender::nodes::node_shader_output_light_cc
 
 /* node type definition */
@@ -21,6 +37,8 @@ void register_node_type_sh_output_light()
 
   sh_node_type_base(&ntype, SH_NODE_OUTPUT_LIGHT, "Light Output", NODE_CLASS_OUTPUT);
   ntype.declare = file_ns::node_declare;
+  node_type_gpu(&ntype, file_ns::node_shader_gpu_output_light);
+
   ntype.no_muting = true;
 
   nodeRegisterType(&ntype);