#rb none
#jira UE-71800
#ROBOMERGE-SOURCE: CL 7712967 in //UE4/Release-4.23/...
#ROBOMERGE-BOT: RELEASE (Release-4.23 -> Main) (v385-7708028)
[CL 7712968 by ben marsh in Main branch]
#lockdown Nick.Penwarden
#rb none
==========================
MAJOR FEATURES + CHANGES
==========================
Change 3209340 on 2016/11/23 by Ben.Marsh
Convert UE4 codebase to an "include what you use" model - where every header just includes the dependencies it needs, rather than every source file including large monolithic headers like Engine.h and UnrealEd.h.
Measured full rebuild times around 2x faster using XGE on Windows, and improvements of 25% or more for incremental builds and full rebuilds on most other platforms.
* Every header now includes everything it needs to compile.
* There's a CoreMinimal.h header that gets you a set of ubiquitous types from Core (eg. FString, FName, TArray, FVector, etc...). Most headers now include this first.
* There's a CoreTypes.h header that sets up primitive UE4 types and build macros (int32, PLATFORM_WIN64, etc...). All headers in Core include this first, as does CoreMinimal.h.
* Every .cpp file includes its matching .h file first.
* This helps validate that each header is including everything it needs to compile.
* No engine code includes a monolithic header such as Engine.h or UnrealEd.h any more.
* You will get a warning if you try to include one of these from the engine. They still exist for compatibility with game projects and do not produce warnings when included there.
* There have only been minor changes to our internal games down to accommodate these changes. The intent is for this to be as seamless as possible.
* No engine code explicitly includes a precompiled header any more.
* We still use PCHs, but they're force-included on the compiler command line by UnrealBuildTool instead. This lets us tune what they contain without breaking any existing include dependencies.
* PCHs are generated by a tool to get a statistical amount of coverage for the source files using it, and I've seeded the new shared PCHs to contain any header included by > 15% of source files.
Tool used to generate this transform is at Engine\Source\Programs\IncludeTool.
[CL 3209342 by Ben Marsh in Main branch]
#UE4 Reducing dependencies on Version.h
#platformnotify Josh.Adams
--------
Integrated using branch Ue4-To-UE4-Fortnite-Simple (reversed) of change#2585810 by Bob.Tellez on 2015/06/12 11:30:33.
[CL 2585846 by Bob Tellez in Main branch]
Whenever a blank engine association is read from a .uproject via GetEngineIdentifierForProject(), it checks up the directory hierarchy for an engine capable of loading it via its .uprojectdirs search directories. If found, it will use that engine's local identifier from the registry, or register it if it doesn't exist.
Setting a project's engine association to an engine which is capable of loading it via it's .uprojectdirs will cause it to write a blank engine association string into the .uproject (and triggering the behaviour above on open).
#codereview Michael.Trepka
[CL 2064463 by Ben Marsh in Main branch]
* Lots of code moved into IDesktopPlatform for sharing with Launcher and Mac (including setting up file associations, querying project versions, etc...)
* Hack to enumerate all the known launcher engine installations. Does not use registry keys any more. Will probably change to use a list of installations generated by the launcher at some point soon.
* List of registered GitHub builds is stored in HKEY_CURRENT_USER
* Switching engine versions is now done through a dialog rather than through the context menu.
* VersionSelector includes a version number for shell integration, allowing it to defer to an existing installation of the same version if necessary.
#codereview Michael.Trepka
[CL 2045845 by Ben Marsh in Main branch]
