Yesterday I posted a tweet that I tried to rebuild my project only in visual studio 2013 community, but it rebuild the entire engine with it. Which is a bit annoying, since you have to wait for some time. I would guess that this is a visual studio issue, but the official UnrealEngine account replied with if I would like to post it on answerhub.
I have a custom version of 4.9 (I didn’t modify much, so that shouldn’t be the issue). I did not change the engine code before pressing “Rebuild only MyProject”.
I ran some experiments in 4.9 as well as our latest internal version of the Engine and was able to see the results that you described. I am in the process of trying to gather more information regarding whether this is being triggered by something on our end, or if it is internal to Visual Studio. Unfortunately the end of year holidays may hamper my ability to get in touch with some of the developers who would have more insight into this.
If you find yourself needing to rebuild your project, we have recommended the following process in the past:
Delete the Binaries, Build, and Intermediate folders for the project.
Delete the project .sln and .suo files.
Right-click on the project’s .uproject file.
Select Generate Visual Studio Project Files.
Open the newly-created .sln file in Visual Studio.
I was able to get some additional information about what you described. It appears that the Unreal Build Tool does not respect the Build Only ProjectName command, and treats it as a normal rebuild. I am not sure if this functionality in Visual Studio is something we will be able to support given how tightly intertwined project, Engine, and UBT code is. For now, if you want to rebuild your project only, you will probably just want to follow the steps that I outlined in my comment above.
Do you have some news to avoid the entire engine rebuild on 4.12 Release?
It could be very helpfull to avoid wasted time on full engine recompile instead only the game
Thanks!
Did the steps that I mentioned in my previous comment not work for you in 4.12? These steps should still provide you with the equivalent of a rebuilt project without having to rebuild the Engine as well.
The steps work for me, but notice that it’s six error-prone steps, and it leaves a button hanging around in MSVC that costs me an hour if I hit it in a moment of inattention. So, obviously, I hit it (I also work on other things than unreal, where rebuild-only is the standard workflow).
An actual fix to Unreal would be very useful, or at least some way to warn the user what’s about to happen and give us say 5s to ctrl-break before doom strikes.
I agree that the current functionality is somewhat less than ideal, especially when the Rebuild Only Project option in Visual Studio is selected by mistake. I have entered UE-35867 to request improvement in this functionality, but I am not sure this is something that we will be able to do.
If a fix is difficult to implement, could we at least have Unreal Build Tool fail with a “project rebuilds not supported” message rather than really begin a full rebuild? Just lost an hour to this.
Unfortunately there isn’t any news about this. The last comment from one of our engineers on that ticket is that UE4 and individual projects are not separate targets that can be built separately. The plan is to see if something can be done using a special commandline option for UBT, but it may not happen soon.
I am experiencing the same issue. I built the engine from the GitHub code, I ran the editor and created a new project. It does not matter what I do, whenever I click “Build” it also rebuilds the whole engine. I tried to follow your steps, deleting the folders and generating new vs project files but it did not work and when I click Project Only → Build it starts building the whole engine again.
