Generating dll while UE4 editor is opened

Here is a reproducible step I found with EGL 4.15.0.

  • Launch EGL 4.15.0 from EGL

  • Create a new C++ ThirdPerson project (named tps16)

  • edit and save tps16.cpp (no actual modification needed)

  • Build with VS2015 (and hot reload DLL is generated successfully)

  • Finish UE4Editor.exe (with its window close button)

  • execute UE4Editor.exe(with double click on tps16.uproject)

  • edit and save tps16.cpp (no actual modification needed)

  • Build with VS2015(Ctrl+Shift+B)

  • and then DLL is generated successfully but UBT reports failed

    2>Build:
    2> Compiling game modules for hot reload
    2> [1/3] Compile tps16.cpp
    2> tps16.cpp
    2> [2/3] Link UE4Editor-tps16-8715.dll
    2> [3/3] Link UE4Editor-tps16-6471.lib
    2> ??? C:\proj2\ue415sample\tps16\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-tps16-8715.lib ??? C:\proj2\ue415sample\tps16\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-tps16-8715.exp ???
    2> ??? C:\proj2\ue415sample\tps16\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-tps16-8715.suppressed.lib ??? C:\proj2\ue415sample\tps16\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-tps16-8715.suppressed.exp ???
    2> -------- End Detailed Actions Stats -----------------------------------------------------------
    2> 1>
    2>ERROR : UBT error : Failed to produce item: C:\proj2\ue415sample\tps16\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-tps16-6471.lib

Don’t care “???” which is because UBT can’t handle Japanese character. These lines means success.
I noticed .lib are numbered wrongly in log. Actual generated .lib is UE4Editor-tps16-8715.lib.

I think this is related to Unreal Engine Issues and Bug Tracker (UE-42041)
(hot reload DLL is wrongly loaded when editor launched, without rebuild)