Document VCPKG_ROOT environment variable and make a command to set it

[the-Arioch]

As a newb I was hit by a failure in bootstrapping/building another project: DDoSolitary/yasfw#49

It seems there is a standard (at least de facto standard) VCPKG_ROOT env-var, but it is neither mentioned in vcpkg's Quick Start, nor set by vcpkg tool.

Can it be documented (documentation is required to fix the exact name of the variable and to also fix relative path from the variable to the executable (for some tools it can be subfolder like %ROOT%\bin\name.exe)), and mentioned in the readme.md ?

Also, can the bootstrap .bat or vcpkg executable be made to set it? The latter - as part of vcpkg integrate install command or as a separate command like vcpkg integrate envvar ?

At least on Windows platform - for what i remember on Windows NT one needs to update HKCU and/or HKLM registry key, then to broadcast some WM_XXX message to make Explorer re-fetch updated env-vars).

Since vcpkg integrate install seems to request UAC elevation anyway, it seems to be a good place to put HKLM env-var adjustment into. If not i'd like to see vcpkg integrate envvar and vcpkg integrate envvar /useronly commands implemented and mentioned in Quick Start documentation.

[dg0yt]

It is not in the quickstart because it isn't needed in regular use cases. But it is documented:
https://github.com/microsoft/vcpkg/blob/master/docs/users/config-environment.md#vcpkg_root

[the-Arioch]

as the root of the vcpkg instance - is what i was afraid of... Without explicit documenting what is "relative path" between "instance root" and "executable of that instance" it is a guess game. It might be obvious for you that vcpkg.exe is expected to be found at %VCPKG_ROOT%\vcpkg.exe and not in some subfolder. But it is "internal" knowledge among seasoned people already in-the know (IOW among the people who do not need the documentation).

As of "in regular use cases" it is again a YMMV case. Even if a novice somehow figures he needs to integrate vcpkg into some another toolset - he is lost how exactly to do it.

A novice one way or another figures he has to plug vcpkg into a pipeline, he googles around and finds https://github.com/microsoft/vcpkg/blob/master/README.md and is hopefully by a single "fineprint" line into https://github.com/microsoft/vcpkg/blob/master/docs/users/integration.md (this link i believe has to be highlighted at least, maybe even put as a separate chapter to be visible from the top of the readme document), and then... hits a wall. Novice user does not immediately use VS IDE, nor does not immediately use CMake.

I believe there has to be a chapter like "Integrating with other development tools/pipelines" and it has to mention that environment variable as a oficcialyl preferred default way to integrate vcpkg with ANY new 3rd party dev-tools. Make it clear to new users and developers HOW you want them to be finding vcpkg unless any special cases.

• General rule - use THIS env-var in THAT specific way.
• Special rules for VS IDE
• Special rules for CMake tool
• Special rules for XXXXX tool, etc