Description

This issue appears to be a continuation of UE-42205. Hot reloads work successfully in projects that were created in 4.15 or 4.16 and are still using the same Engine version that they were created in. However, if a project was created in 4.15 and then upgraded to 4.16, the same failure as mentioned in the previous ticket occurs.

Steps to Reproduce

SETUP:
This repro requires both 4.15 and 4.16 to be installed.

  1. Create a new Basic Code project in 4.15.2.
  2. Add a new class to the project.
  3. Add a new UFUNCTION to the new class.
  4. Build the project in Visual Studio.
  5. Upgrade the project to 4.16.
  6. Open the project in both the Editor and Visual Studio.
  7. Add a blank line to the .cpp file for the class added in step 2.
  8. Build the project in Visual Studio to trigger a hot reload.
  9. After the hot reload completes successfully, add another blank line to the .cpp file for the class added in step 2.
  10. Build the project in Visual Studio to trigger a hot reload.

RESULT:
The build fails in Visual Studio, stating that it failed to produce a .lib file for the project. The error message will appear similar to: ERROR : UBT error : Failed to produce item: D:\Unreal Projects\Current Issues\TestHotReload1 4.16\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-TestHotReload1-7685.lib

EXPECTED:
The build completes successfully.

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Fixed
TypeBug
ComponentCore - Hot Reload
Affect Versions4.16
Target Fix4.17
Fix Commit3475747
CreatedMay 16, 2017
ResolvedJun 19, 2017
UpdatedJun 22, 2017