Merge pull request #82031 from artemcm/RemovePlaceholdersInDepScanner

[Dependency Scanning] Remove obsolete placeholder module concept

lib/DependencyScan/DependencyScanningTool.cpp

@@ -271,7 +271,6 @@ DependencyScanningTool::DependencyScanningTool()
 llvm::ErrorOr<swiftscan_dependency_graph_t>
 DependencyScanningTool::getDependencies(
     ArrayRef<const char *> Command,
-    const llvm::StringSet<> &PlaceholderModules,
     StringRef WorkingDirectory) {
   // There may be errors as early as in instance initialization, so we must ensure
   // we can catch those.