GPUShaderCreateInfo: Add duplication error checking of dependency merging

As of now we do not allow additional infos duplication. We could in the future
but for now assert that this is not the case.

source/blender/gpu/intern/gpu_shader_create_info.cc

@@ -55,6 +55,8 @@ void ShaderCreateInfo::finalize()
   }
   finalized_ = true;
 
+  Set<StringRefNull> deps_merged;
+
   for (auto &info_name : additional_infos_) {
     const ShaderCreateInfo &info = *reinterpret_cast<const ShaderCreateInfo *>(
         gpu_shader_create_info_get(info_name.c_str()));
@@ -86,6 +88,10 @@ void ShaderCreateInfo::finalize()
       }
     };
 
+    if (!deps_merged.add(info.name_)) {
+      assert_no_overlap(false, "additional info already merged via another info");
+    }
+
     if (info.compute_layout_.local_size_x != -1) {
       assert_no_overlap(compute_layout_.local_size_x == -1, "Compute layout already defined");
       compute_layout_ = info.compute_layout_;