Use only named packages from extra registries

[dg0yt]

This change resolves errors from RegistryEntry::get_path_to_version() when the default registry doesn't have a port for a name which is part of some extra registry but not listed in that registry's "packages" configuration field.
This is consistent with RegistrySet::registry_for_port() which only considers the the named packages from the extra registries.

Use case:

{
  "default-registry": {
    "kind": "filesystem",
    "path": "/my/tiny/repository"
  },
  "registries": [
    {
      "kind": "git",
      "repository": "https://github.com/microsoft/vcpkg",
      "packages": [ "vcpkg-cmake", "vcpkg-cmake-config" ]
    }
  ]
}

[ras0219-msft]

Thanks for the PR! This change looks generally good to me, however could you go into more detail about what the precise error is and what the expected result was?

[strega-nil]

FWIW, this is why https://github.com/microsoft/vcpkg-tool/pull/35/files#diff-d4fe92b1ebc56fd05568a18c509672434c578cf4e147b2d5aad36226c026ff00L440-L447 exists; is there a reason that you're making this change?

[dg0yt]

is there a reason that you're making this change?

I want to combine

• a custom registry of ports ("default-registry")
• selected ports from the main vcpkg repository ("registries"[0]).

could you go into more detail about what the precise error is and what the expected result was?

vcpkg commands fail like this:

$ vcpkg search internal
Error: Couldn't find the versions database file: /tmp/test/versions/3-/3fd.json
Note: Updating vcpkg by rerunning bootstrap-vcpkg may resolve this failure.

where 3fd.json neither exists in default-registry (/tmp/test) nor is listed in registries[0].packages.

Reproducer (bash, but modeled after azure-pipelines/end-to-end-tests-dir/registries.ps1):

test -d vcpkg-tool || git clone https://github.com/microsoft/vcpkg-tool.git

mkdir -p ports
cp -R vcpkg-tool/azure-pipelines/e2e_ports/vcpkg-internal-e2e-test-port ports/

mkdir -p versions/v-
cp vcpkg-tool/azure-pipelines/e2e_ports/versions/baseline.json versions/
cat > versions/v-/vcpkg-internal-e2e-test-port.json <<END_PORT
{
  "versions" : {
    "version-string": "1.0.0",
    "path": "$PWD/ports/vcpkg-internal-e2e-test-port"
  }
}
END_PORT

test -d vcpkg || git clone https://github.com/microsoft/vcpkg.git
cat > vcpkg/vcpkg-configuration.json <<END_CONFIG
{
  "default-registry": {
    "kind": "filesystem",
    "path": "$PWD"
  },
  "registries": [
    {
      "kind": "git",
      "repository": "https://github.com/microsoft/vcpkg",
      "packages": [ "vcpkg-cmake", "vcpkg-cmake-config" ]
    }
  ]
}
END_CONFIG

export VCPKG_ROOT=$PWD/vcpkg
export VCPKG_FEATURE_FLAGS=registries

vcpkg --debug search internal

[ras0219-msft]

This LGTM, loading all registry ports shouldn't enumerate ports beyond default + packages of each other registry. It should exactly match the valid values of RegistrySet::registry_for_port().

[ras0219-msft]

@strega-nil RegistrySet::registry_for_port() doesn't guarantee that the port name is valid for the registry, so the if (!impl) check doesn't handle @dg0yt's case.