Different location of manifest vcpkg_installed between non-integrate and integrate with build system

[WangWeiLin-MV]

This issue is a duplicate of microsoft/vcpkg#39385, originally initiated by @wardw.

In manifest mode, when integrate vcpkg with build system, vcpkg_installed is placed in the build directory rather than the same directory that contains the manifest file which contradicts the documentation.

From documents

vcpkg/consume/manifest-mode and vcpkg/consume/manifest-mode.md

Therefore, each project can have its own manifest and its own set of dependencies that do not conflict with other projects' dependencies.

vcpkg/concepts/manifest-mode and vcpkg/concepts/manifest-mode.md

Instead, each manifest gets its own installation directory named vcpkg_installed; the vcpkg_installed directory is created in the same directory that contains the manifest file.

vcpkg/reference/installation-tree-layout and vcpkg/reference/installation-tree-layout.md

In manifest mode, each manifest file has a corresponding vcpkg_installed directory.

From codes

When using manifest mode, given vcpkg.json, taking the build tool CMake and the generator Visual Studio 17 2022 as an example:

• For non-integrated usage

  • Install packages by the command line command vcpkg install
  • The vcpkg_installed directory is created in the same directory that contains the manifest file
  • See here vcpkg-tool:tag:2024-06-10:src/vcpkg/vcpkgpaths.cpp#L349 that InstalledPaths by manifest_dir / "vcpkg_installed"

• For integrated usage

  • The packages are installed when CMake is generating project through the toolchain file
  • The vcpkg_installed directory is created in the build directory instead of like non-integrated mode.
  • This behavior changed in vcpkg-pr-12227-228ade9:scripts/buildsystems/vcpkg.cmake#L203 that from _VCPKG_MANIFEST_DIR to CMAKE_BINARY_DIR