Response files should be named using the hash of the command line arguments only

Author: owenv

Sources/SwiftDriver/Execution/ArgsResolver.swift

@@ -15,6 +15,7 @@ import class Foundation.NSLock
 import func TSCBasic.withTemporaryDirectory
 import protocol TSCBasic.FileSystem
 import struct TSCBasic.AbsolutePath
+import struct TSCBasic.SHA256
 
 @_implementationOnly import Yams
 
@@ -208,7 +209,8 @@ public final class ArgsResolver {
       assert(!forceResponseFiles || job.supportsResponseFiles,
              "Platform does not support response files for job: \(job)")
       // Match the integrated driver's behavior, which uses response file names of the form "arguments-[0-9a-zA-Z].resp".
-      let responseFilePath = temporaryDirectory.appending(component: "arguments-\(abs(job.hashValue)).resp")
+      let hash = SHA256().hash(resolvedArguments.joined(separator: " ")).hexadecimalRepresentation
+      let responseFilePath = temporaryDirectory.appending(component: "arguments-\(hash).resp")
 
       // FIXME: Need a way to support this for distributed build systems...
       if let absPath = responseFilePath.absolutePath {

Tests/SwiftDriverTests/SwiftDriverTests.swift

@@ -1712,6 +1712,26 @@ final class SwiftDriverTests: XCTestCase {
       XCTAssertFalse(resolvedArgs.contains { $0.hasPrefix("@") })
     }
   }
+    
+  func testResponseFileDeterministicNaming() throws {
+    #if !os(macOS)
+    throw XCTSkip("Test assumes macOS response file quoting behavior")
+    #endif
+    do {
+      let manyArgs = (1...20000).map { "-DTEST_\($0)" }
+      var driver = try Driver(args: ["swift"] + manyArgs + ["/foo.swift"])
+      let jobs = try driver.planBuild()
+      XCTAssertTrue(jobs.count == 1 && jobs[0].kind == .interpret)
+      let interpretJob = jobs[0]
+      let resolver = try ArgsResolver(fileSystem: localFileSystem)
+      let resolvedArgs: [String] = try resolver.resolveArgumentList(for: interpretJob)
+      XCTAssertTrue(resolvedArgs.count == 3)
+      XCTAssertEqual(resolvedArgs[1], "-frontend")
+      XCTAssertEqual(resolvedArgs[2].first, "@")
+      let responseFilePath = try AbsolutePath(validating: String(resolvedArgs[2].dropFirst()))
+      XCTAssertEqual(responseFilePath.basename, "arguments-b8821417b0e2b7903ed3121610ab6a9721637b459c6703ef1af18297c2a4998f.resp")
+    }
+  }
 
   func testSpecificJobsResponseFiles() throws {
     // The jobs below often take large command lines (e.g., when passing a large number of Clang