Add a bare metal plugin (for "none" triples)

This is just going in SWBUniversalPlatform for now for simplicity / bringup, and should maybe move into a new SWBNonePlatformPlugin later on.

Closes swiftlang#726

Author: jakepetroules

.editorconfig

@@ -11,3 +11,6 @@ xcode_trim_whitespace_on_empty_lines = true
 
 [*.{yml,yaml}]
 indent_size = 2
+
+[CMakeLists.txt]
+indent_size = 2

Sources/SWBUniversalPlatform/BareMetal.swift

@@ -0,0 +1,61 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See http://swift.org/LICENSE.txt for license information
+// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+public import SWBUtil
+public import SWBCore
+import SWBMacro
+import Foundation
+
+struct BareMetalPlatformExtension: PlatformInfoExtension {
+    func additionalPlatforms(context: any PlatformInfoExtensionAdditionalPlatformsContext) throws -> [(path: Path, data: [String: PropertyListItem])] {
+        [
+            (.root, [
+                "Type": .plString("Platform"),
+                "Name": .plString("none"),
+                "Identifier": .plString("none"),
+                "Description": .plString("Bare Metal"),
+                "FamilyName": .plString("None"),
+                "FamilyIdentifier": .plString("none"),
+                "IsDeploymentPlatform": .plString("YES"),
+            ])
+        ]
+    }
+}
+
+@_spi(Testing) public struct BareMetalSDKRegistryExtension: SDKRegistryExtension {
+    public func additionalSDKs(context: any SDKRegistryExtensionAdditionalSDKsContext) async throws -> [(path: Path, platform: Platform?, data: [String: PropertyListItem])] {
+        guard let platform = context.platformRegistry.lookup(name: "none") else {
+            return []
+        }
+
+        let defaultProperties: [String: PropertyListItem] = [
+            "SDK_STAT_CACHE_ENABLE": "NO",
+        ]
+
+        return [(.root, platform, [
+            "Type": .plString("SDK"),
+            "Version": .plString("0.0.0"),
+            "CanonicalName": .plString("none"),
+            "IsBaseSDK": .plBool(true),
+            "DefaultProperties": .plDict([
+                "PLATFORM_NAME": .plString("none"),
+            ].merging(defaultProperties, uniquingKeysWith: { _, new in new })),
+            "CustomProperties": .plDict([:]),
+            "SupportedTargets": .plDict([
+                "none": .plDict([
+                    "Archs": .plArray([]),
+                    "LLVMTargetTripleSys": .plString("none"),
+                ])
+            ]),
+        ])]
+    }
+}

Sources/SWBUniversalPlatform/CMakeLists.txt

@@ -9,6 +9,7 @@ See http://swift.org/CONTRIBUTORS.txt for Swift project authors
 ]]
 
 add_library(SWBUniversalPlatform
+  BareMetal.swift
   CopyPlistFile.swift
   CopyStringsFile.swift
   CppTool.swift

Sources/SWBUniversalPlatform/Plugin.swift

@@ -20,6 +20,9 @@ public let initializePlugin: PluginInitializationFunction = { manager in
     manager.register(UniversalPlatformSpecsExtension(), type: SpecificationsExtensionPoint.self)
     manager.register(UniversalPlatformTaskProducerExtension(), type: TaskProducerExtensionPoint.self)
     manager.register(UniversalPlatformTaskActionExtension(), type: TaskActionExtensionPoint.self)
+
+    manager.register(BareMetalPlatformExtension(), type: PlatformInfoExtensionPoint.self)
+    manager.register(BareMetalSDKRegistryExtension(), type: SDKRegistryExtensionPoint.self)
 }
 
 struct UniversalPlatformSpecsExtension: SpecificationsExtension {

Tests/SWBCoreTests/SettingsTests.swift

@@ -1773,7 +1773,7 @@ import SWBMacro
         #expect(!core.platformRegistry.platforms.isEmpty)
         for developmentTeam in ["ABCDWXYZ", ""] {
             for platform in core.platformRegistry.platforms {
-                if ["android", "freebsd", "linux", "qnx", "windows"].contains(platform.name) {
+                if ["android", "freebsd", "linux", "none", "qnx", "windows"].contains(platform.name) {
                     continue
                 }
                 for sdk in platform.sdks {

Tests/SWBTaskConstructionTests/PackageProductConstructionTests.swift

@@ -673,7 +673,7 @@ fileprivate struct PackageProductConstructionTests: CoreBasedTests {
     @Test(.requireSDKs(.macOS))
     func packageProductReferences() async throws {
         let core = try await getCore()
-        let allPlatforms = core.platformRegistry.platforms.filter { !$0.isSimulator && core.sdkRegistry.lookup($0.name) != nil }
+        let allPlatforms = core.platformRegistry.platforms.filter { !$0.isSimulator && core.sdkRegistry.lookup($0.name) != nil && $0.name != "none" }
         #expect(allPlatforms.count > 0) // ensure we don't just pass this test because we somehow ended up with no platforms
         let targets = allPlatforms.map { $0.name }.map {
             commandLineDynamicLibraryTarget(name: "\($0)Lib", buildSettings: ["SDKROOT": $0])