Merge pull request swiftlang#1972 from nkcsgexi/dedupe-jobs

PrebuiltModuleGen: dedupe prebuilt module jobs

Author: nkcsgexi

Sources/SwiftDriver/Jobs/PrebuiltModulesJob.swift

@@ -812,13 +812,13 @@ extension Driver {
  return (key, outputPaths)
  })
 
- func collectSwiftModuleNames(_ ids: [ModuleDependencyId]) -> [String] {
- return ids.compactMap { id in
+ func collectUniqueSwiftModuleNames(_ ids: [ModuleDependencyId]) -> [String] {
+ return Array(Set(ids.compactMap { id in
  if case .swift(let module) = id {
  return module
  }
  return nil
- }
+ }))
  }
 
  func getSwiftDependencies(for module: String) -> [String] {
@@ -827,7 +827,7 @@ extension Driver {
  guard !dependencies.isEmpty else {
  return []
  }
- return collectSwiftModuleNames(dependencies)
+ return collectUniqueSwiftModuleNames(dependencies)
  }
 
  func getOutputPaths(withName modules: [String], loadableFor arch: Triple.Arch) throws -> [TypedVirtualPath] {
@@ -870,7 +870,7 @@ extension Driver {
  // Keep track of modules we haven't handled.
  var unhandledModules = Set<String>(inputMap.keys)
  // Start from those modules explicitly imported into the file under scanning
- var openModules = collectSwiftModuleNames(dependencyGraph.mainModule.allDependencies)
+ var openModules = collectUniqueSwiftModuleNames(dependencyGraph.mainModule.allDependencies)
  var idx = 0
  while idx != openModules.count {
  let module = openModules[idx]