Don't let unsupported ports pull in dependencies

azure-pipelines/e2e_ci/zzz-expected-port/portfile.cmake

@@ -0,0 +1 @@
+set(VCPKG_POLICY_EMPTY_PACKAGE enabled)

azure-pipelines/e2e_ci/zzz-expected-port/vcpkg.json

@@ -0,0 +1,10 @@
+{
+  "name": "zzz-expected-port",
+  "version": "1",
+  "features": {
+    "zzz-unexpected-feature": {
+      "description": "Cannot be installed",
+      "supports": "native & !native"
+    }
+  }
+}

azure-pipelines/e2e_ci/zzz-unexpected-port/portfile.cmake

@@ -0,0 +1 @@
+set(VCPKG_POLICY_EMPTY_PACKAGE enabled)

azure-pipelines/e2e_ci/zzz-unexpected-port/vcpkg.json

@@ -0,0 +1,14 @@
+{
+  "name": "zzz-unexpected-port",
+  "version": "1",
+  "description": "Cannot be installed",
+  "supports": "native & !native",
+  "dependencies": [
+    {
+      "name": "zzz-expected-port",
+      "features": [
+        "zzz-unexpected-feature"
+      ]
+    }
+  ]
+}

azure-pipelines/end-to-end-tests-dir/ci.ps1

@@ -1,13 +1,26 @@
 . $PSScriptRoot/../end-to-end-tests-prelude.ps1
 
 # Not a number
-Run-Vcpkg ci --triplet=$Triplet --x-skipped-cascade-count=fish
+Run-Vcpkg ci --dry-run --triplet=$Triplet --x-skipped-cascade-count=fish
 Throw-IfNotFailed
 
 # Negative
-Run-Vcpkg ci --triplet=$Triplet --x-skipped-cascade-count=-1
+Run-Vcpkg ci --dry-run --triplet=$Triplet --x-skipped-cascade-count=-1
 Throw-IfNotFailed
 
 # Clearly not the correct answer
-Run-Vcpkg ci --triplet=$Triplet --x-skipped-cascade-count=1000
+Run-Vcpkg ci --dry-run --triplet=$Triplet --x-skipped-cascade-count=1000
 Throw-IfNotFailed
+
+# Regular ci; may take a few seconds to complete
+$port_list = Run-VcpkgAndCaptureOutput ci --dry-run --triplet=$Triplet --binarysource=clear --overlay-ports="$PSScriptRoot/../e2e_ci"
+Throw-IfFailed
+if ($port_list -match "zzz-unexpected-port[^ ]*[ ]*->") {
+    throw 'Detected installation of "zzz-unexpected-port"'
+}
+if ($port_list -match "zzz-unexpected-feature[^ ]*[ ]*->") {
+    throw 'Detected installation of "zzz-unexpected-feature"'
+}
+if ($port_list -notmatch "zzz-expected-port[^ ]*[ ]*->") {
+    throw 'Did not detect installation of "zzz-expected-port"'
+}

src/vcpkg/commands.ci.cpp

@@ -149,6 +149,7 @@ namespace vcpkg::Commands::CI
                                         const std::vector<FullPackageSpec>& specs,
                                         const CreateInstallPlanOptions& serialize_options)
     {
+        // Initialize for all ports
         std::vector<PackageSpec> packages_with_qualified_deps;
         for (auto&& spec : specs)
         {
@@ -158,10 +159,21 @@ namespace vcpkg::Commands::CI
                 packages_with_qualified_deps.push_back(spec.package_spec);
             }
         }
-
         var_provider.load_dep_info_vars(packages_with_qualified_deps, serialize_options.host_triplet);
-        auto action_plan = create_feature_install_plan(provider, var_provider, specs, {}, serialize_options);
+        var_provider.load_tag_vars(specs, provider, serialize_options.host_triplet);
+
+        // Determine set of ports which is applicable to the target
+        const auto applicable_specs = Util::filter(specs, [&](auto& spec) -> bool {
+            auto&& scfl = provider.get_control_file(spec.package_spec.name()).value_or_exit(VCPKG_LINE_INFO);
+            const auto& supports_expression = scfl.source_control_file->core_paragraph->supports_expression;
+            return supports_expression.is_empty()
+                       ? true
+                       : supports_expression.evaluate(
+                             var_provider.get_tag_vars(spec.package_spec).value_or_exit(VCPKG_LINE_INFO));
+        });
 
+        // Create install plan and complement initialization for ports to be installed for the host
+        auto action_plan = create_feature_install_plan(provider, var_provider, applicable_specs, {}, serialize_options);
         var_provider.load_tag_vars(action_plan, provider, serialize_options.host_triplet);
 
         Checks::check_exit(VCPKG_LINE_INFO, action_plan.already_installed.empty());