Merge pull request #2308 from bnbarham/remove-precondition

Avoid crashing when loading client plugins from the same path

Author: bnbarham

Sources/SourceKitD/SourceKitD.swift

@@ -100,7 +100,7 @@ package enum SKDError: Error, Equatable {
 /// `set_notification_handler`, which are global state managed internally by this class.
 package actor SourceKitD {
   /// The path to the sourcekitd dylib.
-  package let path: URL
+  nonisolated package let path: URL
 
   /// The handle to the dylib.
   private let dylib: DLHandle

Sources/SwiftSourceKitClientPlugin/ClientPlugin.swift

@@ -28,8 +28,20 @@ public func sourcekitd_plugin_initialize_2(
   _ params: sourcekitd_api_plugin_initialize_params_t,
   _ sourcekitdPath: UnsafePointer<CChar>
 ) {
+  let pluginPath = URL(fileURLWithPath: String(cString: sourcekitdPath))
+
+  if SourceKitD.isPluginLoaded {
+    // When `DYLD_(FRAMEWORK|LIBRARY)_PATH` is set, `dlopen` will first check if the basename of the provided path is
+    // within any of its search paths. Thus it's possible that only a single library is loaded for each toolchain,
+    // rather than a separate like we expect. The paths should be equal in this case, since the client plugin is loaded
+    // based on the path of `sourcekitd.framework` (and we should only have one for the same reason). Allow this case
+    // and just avoid re-initializing.
+    precondition(SourceKitD.forPlugin.path == pluginPath)
+    return
+  }
+
   SourceKitD.forPlugin = try! SourceKitD(
-    dylib: URL(fileURLWithPath: String(cString: sourcekitdPath)),
+    dylib: pluginPath,
     pluginPaths: nil,
     initialize: false
   )

Sources/SwiftSourceKitPluginCommon/DynamicallyLoadedSourceKitdD+forPlugin.swift

@@ -17,6 +17,11 @@ import SwiftExtensions
 
 extension SourceKitD {
   private static nonisolated(unsafe) var _forPlugin: SourceKitD?
+
+  package static var isPluginLoaded: Bool {
+    return _forPlugin != nil
+  }
+
   package static var forPlugin: SourceKitD {
     get {
       guard let _forPlugin else {