Editing sets and maps of structures does not correctly check for duplicates

Customer created a custom DataTable with a TSet Property and saw the behavior of allowing duplicate elements within the TSet, which is not allowed. See TSet Documentation for more information.

This is a general problem with sets/maps of Structs, the FPropertyValueImpl::ImportText function does not correctly handle the case of modifying something inside a struct inside a map, the Set code needs to traverse up the property chain further

Repro Ratio: 3/3

Tested in //UE4/Release-4.27 @ CL#18319896 and the issue did occur there, it is not a regression.

This same issue occurs

SIMPLER REPRO

1. Open the editor in any project
2. Create a new Blueprint Structure called KeyStruct
3. Add one member to it, a GameplayTag
4. Open up any blueprint, create a new variable of type KeyStruct, and change it to a Set (or map, same issue occurs)
5. Click + to add a new item, set the tag member to the first tag in the list
6. Click + again, set the new tag member to the same tag
7. Note that it allows two duplicate entries, which does not happen for sets of GameplayTag

ORIGINAL REPRO

1. Create Blank C++ Project
   • for purposes of easy to understand repro steps I will refer to the project as MyProject
2. Open MyProject.h in Visual Studio
3. add include lines before the MyProject.generated.h include line:

   #include "GameplayTagContainer.h"
   #include "Engine/DataTable.h"
    

4. Add following code underneath the include statements.

    USTRUCT(BlueprintType)
    struct FTestStruct_Inner
    {
         GENERATED_BODY()
    
         UPROPERTY(EditAnywhere)
              FGameplayTag myTag;
    
              bool operator==(const FTestStruct_Inner& ftsi){};
              bool operator!=(const FTestStruct_Inner& ftsi) {};
              friend uint32 GetTypeHash(const FTestStruct_Inner& hash) { return 0; };
    
    };
   
    USTRUCT(BlueprintType)
    struct FTestSTruct_Row : public FTableRowBase
    {
         GENERATED_BODY()
    
         UPROPERTY(EditAnywhere)
              TSet<FTestStruct_Inner> mySet;
    };
   

5. In Editor go to Edit>Project Settings>Gameplay Tags
6. Under Gameplay Tag Table List create a new DataTable implementing the new custom row type
   • Click the plus sign to add new table
   • In Dropdown select DataTable
   • Name your table and save
   • Choose FTestStruct_Row when prompted
7. In Content Browser, open the new Data Table
8. Add a new Row
9. within the row, Add a new TSet element and create or choose a Gameplay Tag
10. within the same row, add a second TSet element and choose the same Gameplay Tag

Blueprint Steps

1. Create a new blueprint class
2. Open Blueprint
3. Create a new variable and choose type FTestStruct_Row
4. In details panel add two elements to the TSet variable each with the same Gameplay Tag

Expected Result: With the TSet property the DataTable should not allow duplicate entries.

Actual Results: Duplicate entries are allowed and no indication within the Editor Console that this is an issue. However, when looking over logs you will see the following error:

Error: UDataTable::GetAllRows : Incorrect type specified for DataTable '/Game/PickUps.PickUps' (UGameplayTagsManager::PopulateTreeFromDataTable)