Move targets(dependingOn:) call out of the changed files loop

We can call this function once we have gathered all changed targets instead of once for each changed file, which should be slightly more performant.

Author: ahoppen

Sources/SemanticIndex/SemanticIndexManager.swift

@@ -382,19 +382,19 @@ package final actor SemanticIndexManager {
     let changedFiles = events.map(\.uri)
     await indexStoreUpToDateTracker.markOutOfDate(changedFiles)
 
-    // Preparation tracking should be per file. For now consider any non-known-language change as having to re-prepare
-    // the target itself so that we re-prepare potential input files to plugins.
-    // https://github.com/swiftlang/sourcekit-lsp/issues/1975
     var outOfDateTargets = Set<BuildTargetIdentifier>()
+    var targetsOfChangedFiles = Set<BuildTargetIdentifier>()
     for file in changedFiles {
       let changedTargets = await buildSystemManager.targets(for: file)
+      targetsOfChangedFiles.formUnion(changedTargets)
       if Language(inferredFromFileExtension: file) == nil {
+        // Preparation tracking should be per file. For now consider any non-known-language change as having to
+        // re-prepare the target itself so that we re-prepare potential input files to plugins.
+        // https://github.com/swiftlang/sourcekit-lsp/issues/1975
         outOfDateTargets.formUnion(changedTargets)
       }
-
-      let dependentTargets = await buildSystemManager.targets(dependingOn: changedTargets)
-      outOfDateTargets.formUnion(dependentTargets)
     }
+    outOfDateTargets.formUnion(await buildSystemManager.targets(dependingOn: targetsOfChangedFiles))
     if !outOfDateTargets.isEmpty {
       logger.info(
         """