[Manifests]: Choose a better policy for automatically update outdated ports

[Milerius]

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Is your feature request related to a problem? Please describe.

As it stands, in vcpkg.cmake it seems that when a manifest is detected we choose a folder in the CMAKE_BINARY_DIR rather than the vcpkg installation folder:

https://github.com/microsoft/vcpkg/blob/master/scripts/buildsystems/vcpkg.cmake#L236

This is currently the case because it allows you with each new CMake build to detect possible port updates.

The problem with this approach is that it's slow, must iterate over all manifest dependencies and copy from the cache folder to the CMake output folder.

Take around 22seconds for my project: Total elapsed time: 22.95 s (and this each time i delete the cmake cache and generate again)

Proposed solution

First of all keep installed dir as it is: set(_VCPKG_INSTALLED_DIR ${_VCPKG_ROOT_DIR}/installed)

And instead of running install: https://github.com/microsoft/vcpkg/blob/master/scripts/buildsystems/vcpkg.cmake#L372

run it this way:

vcpkg remove --x-manifest-root=path_to_manifest --outdated --recurse --overlay-ports=path_to_custom_ports

vcpkg install --x-manifest-root=path_to_manifest --recurse --overlay-ports=path_to_custom_ports --clean-after-build

^ This is much faster and safe (remove outdated dependencies, and installing only outdated one, and don't waste precious seconds on copying existing binaries from cache)

I would be more than happy to implement this approach, but i need to know if everyone agree with my approach before

Describe alternatives you've considered

• None

Additional context

my vcpkg.json:

{
  "name": "atomicdex-desktop",
  "version-string": "0.3.0",
  "dependencies": [
    "entt",
    "folly",
    "boost-multiprecision",
    "boost-random",
    "boost-lockfree",
    "doctest",
    "fmt",
    "nlohmann-json",
    "range-v3",
    "libsodium",
    "spdlog",
    "date",
    "cpprestsdk",
    "cpp-taskflow"
  ]
}