[Macros] Add 'LibraryPluginProvider'

Package.swift

@@ -124,6 +124,14 @@ let package = Package(
       dependencies: ["_SwiftSyntaxTestSupport", "SwiftIDEUtils", "SwiftParser", "SwiftSyntax"]
     ),
 
+    // MARK: SwiftLibraryPluginProvider
+
+    .target(
+      name: "SwiftLibraryPluginProvider",
+      dependencies: ["SwiftSyntaxMacros", "SwiftCompilerPluginMessageHandling"],
+      exclude: ["CMakeLists.txt"]
+    ),
+
     // MARK: SwiftSyntax
 
     .target(

Sources/CMakeLists.txt

@@ -10,6 +10,7 @@ add_subdirectory(_SwiftSyntaxCShims)
 add_subdirectory(SwiftBasicFormat)
 add_subdirectory(SwiftSyntax)
 add_subdirectory(SwiftDiagnostics)
+add_subdirectory(SwiftLibraryPluginProvider)
 add_subdirectory(SwiftParser)
 add_subdirectory(SwiftParserDiagnostics)
 add_subdirectory(SwiftRefactor)

Sources/SwiftCompilerPluginMessageHandling/CompilerPluginMessageHandler.swift

@@ -25,6 +25,8 @@ public enum PluginFeature: String {
 }
 
 /// A type that provides the actual plugin functions.
+///
+/// Note that it's an implementation's responsibility to cache the API results as needed.
 @_spi(PluginMessage)
 public protocol PluginProvider {
   /// Resolve macro type by the module name and the type name.

Sources/SwiftLibraryPluginProvider/CMakeLists.txt

@@ -0,0 +1,16 @@
+# This source file is part of the Swift.org open source project
+#
+# Copyright (c) 2024 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 Swift project authors
+
+add_swift_syntax_library(SwiftLibraryPluginProvider
+  LibraryPluginProvider.swift
+)
+
+target_link_swift_syntax_libraries(SwiftLibraryPluginProvider PUBLIC
+  SwiftSyntaxMacros
+  SwiftCompilerPluginMessageHandling
+)

Sources/SwiftLibraryPluginProvider/LibraryPluginProvider.swift

@@ -0,0 +1,203 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift open source project
+//
+// Copyright (c) 2024 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
+//
+//===----------------------------------------------------------------------===//
+
+#if swift(>=6.0)
+public import SwiftSyntaxMacros
+@_spi(PluginMessage) public import SwiftCompilerPluginMessageHandling
+// NOTE: Do not use '_SwiftSyntaxCShims' for 'dlopen' and 'LoadLibraryW' (Windows)
+// because we don't want other modules depend on 'WinSDK'.
+#if canImport(Darwin)
+private import Darwin
+#elseif canImport(Glibc)
+private import Glibc
+#elseif canImport(Musl)
+private import Musl
+#elseif canImport(WinSDK)
+private import WinSDK
+#endif
+#else
+import SwiftSyntaxMacros
+@_spi(PluginMessage) import SwiftCompilerPluginMessageHandling
+#if canImport(Darwin)
+@_implementationOnly import Darwin
+#elseif canImport(Glibc)
+@_implementationOnly import Glibc
+#elseif canImport(Musl)
+@_implementationOnly import Musl
+#elseif canImport(WinSDK)
+@_implementationOnly import WinSDK
+#endif
+#endif
+
+/// Singleton 'PluginProvider' that can serve shared library plugins.
+@_spi(PluginMessage)
+public class LibraryPluginProvider: PluginProvider {
+  struct LoadedLibraryPlugin {
+    var libraryPath: String
+    var handle: UnsafeMutableRawPointer
+  }
+
+  struct MacroRef: Hashable {
+    var moduleName: String
+    var typeName: String
+  }
+
+  /// Loaded dynamic link library handles associated with the module name.
+  var loadedLibraryPlugins: [String: LoadedLibraryPlugin] = [:]
+
+  /// Resolved macros cache.
+  var resolvedMacros: [MacroRef: Macro.Type] = [:]
+
+  private init() {}
+
+  /// Singleton.
+  @MainActor
+  public static let shared: LibraryPluginProvider = LibraryPluginProvider()
+
+  public var features: [PluginFeature] {
+    [.loadPluginLibrary]
+  }
+
+  public func loadPluginLibrary(libraryPath: String, moduleName: String) throws {
+    if let loaded = loadedLibraryPlugins[moduleName] {
+      guard loaded.libraryPath == libraryPath else {
+        // NOTE: Should be unreachable. Compiler should not load different
+        // library for the same module name.
+        throw LibraryPluginError(
+          message:
+            "library plugin for module '\(moduleName)' is already loaded from different path '\(loaded.libraryPath)'"
+        )
+      }
+      return
+    }
+
+    let dlHandle = try _loadLibrary(libraryPath)
+
+    loadedLibraryPlugins[moduleName] = LoadedLibraryPlugin(
+      libraryPath: libraryPath,
+      handle: dlHandle
+    )
+  }
+
+  public func resolveMacro(moduleName: String, typeName: String) throws -> SwiftSyntaxMacros.Macro.Type {
+    let macroRef = MacroRef(moduleName: moduleName, typeName: typeName)
+    if let resolved = resolvedMacros[macroRef] {
+      return resolved
+    }
+
+    // Find 'dlopen'ed library for the module name.
+    guard let plugin = loadedLibraryPlugins[moduleName] else {
+      // NOTE: Should be unreachable. Compiler should not use this server
+      // unless the plugin loading succeeded.
+      throw LibraryPluginError(message: "plugin not loaded for module '\(moduleName)'")
+    }
+
+    // Lookup the type metadata.
+    guard let type = _findAnyType(moduleName, typeName) else {
+      throw LibraryPluginError(
+        message: "type '\(moduleName).\(typeName)' could not be found in library plugin '\(plugin.libraryPath)'"
+      )
+    }
+
+    // The type must be a 'Macro' type.
+    guard let macro = type as? Macro.Type else {
+      throw LibraryPluginError(
+        message:
+          "type '\(moduleName).\(typeName)' is not a valid macro implementation type in library plugin '\(plugin.libraryPath)'"
+      )
+    }
+
+    // Cache the resolved type.
+    resolvedMacros[macroRef] = macro
+    return macro
+  }
+}
+
+#if os(Windows)
+private func _loadLibrary(_ path: String) throws -> UnsafeMutableRawPointer {
+  // Create NULL terminated UTF16 string.
+  let utf16Path = UnsafeMutableBufferPointer<UInt16>.allocate(capacity: path.utf16.count + 1)
+  defer { utf16Path.deallocate() }
+  let end = utf16Path.initialize(fromContentsOf: path.utf16)
+  utf16Path.initializeElement(at: end, to: 0)
+
+  guard let dlHandle = LoadLibraryW(utf16Path.baseAddress) else {
+    // FIXME: Format the error code to string.
+    throw LibraryPluginError(message: "loader error: \(GetLastError())")
+  }
+  return UnsafeMutableRawPointer(dlHandle)
+}
+#else
+private func _loadLibrary(_ path: String) throws -> UnsafeMutableRawPointer {
+  guard let dlHandle = dlopen(path, RTLD_LAZY | RTLD_LOCAL) else {
+    throw LibraryPluginError(message: "loader error: \(String(cString: dlerror()))")
+  }
+  return dlHandle
+}
+#endif
+
+private func _findAnyType(_ moduleName: String, _ typeName: String) -> Any.Type? {
+  // Create a mangled name for struct, enum, and class. And use a runtime
+  // function to find the type. Note that this simple mangling works even if the
+  // actual symbol name doesn't match with it. i.e. We don't need to perform
+  // punycode encodings or word substitutions.
+  // FIXME: This is process global. Can we limit it to a specific .dylib ?
+  for suffix in [ /*struct*/"V", /*enum*/ "O", /*class*/ "C"] {
+    let mangled = "\(moduleName.utf8.count)\(moduleName)\(typeName.utf8.count)\(typeName)\(suffix)"
+    if let type = _typeByName(mangled) {
+      return type
+    }
+  }
+  return nil
+}
+
+private struct LibraryPluginError: Error, CustomStringConvertible {
+  var description: String
+  init(message: String) {
+    self.description = message
+  }
+}
+
+// Compatibility shim for SE-0370
+#if swift(<5.8)
+extension UnsafeMutableBufferPointer {
+  private func initialize(fromContentsOf source: some Collection<Element>) -> Index {
+    let count = source.withContiguousStorageIfAvailable {
+      guard let sourceAddress = $0.baseAddress, !$0.isEmpty else {
+        return 0
+      }
+      precondition(
+        $0.count <= self.count,
+        "buffer cannot contain every element from source."
+      )
+      baseAddress?.initialize(from: sourceAddress, count: $0.count)
+      return $0.count
+    }
+    if let count {
+      return startIndex.advanced(by: count)
+    }
+
+    var (iterator, copied) = self.initialize(from: source)
+    precondition(
+      iterator.next() == nil,
+      "buffer cannot contain every element from source."
+    )
+    return startIndex.advanced(by: copied)
+  }
+
+  private func initializeElement(at index: Index, to value: Element) {
+    precondition(startIndex <= index && index < endIndex)
+    let p = baseAddress!.advanced(by: index)
+    p.initialize(to: value)
+  }
+}
+#endif

Sources/_SwiftSyntaxCShims/include/_includes.h

@@ -25,7 +25,11 @@
 //===----------------------------------------------------------------------===//
 
 #if defined(_WIN32)
+// NOTE: Do NOT include "WinSDK" headers here.
+// This is a part of compiler. If we use 'WinSDK' here, the compiler links with
+// swiftWinSDK.dll when (re)bulding it, and fails because it's used.
 #include <io.h>
+
 #elif defined(__unix__) || defined(__APPLE__)
 #include <unistd.h>
 #endif