From e5e839fc4787638eead4d69c5cbc55f26bc87a40 Mon Sep 17 00:00:00 2001
From: Artem Chikin <achikin@apple.com>
Date: Tue, 3 Dec 2024 09:44:47 -0800
Subject: [PATCH] Disable in-process target-info and supported-features queries
 using libSwiftScan

When building the compiler toolchain, there is currently a race condition which makes it so that the 'libSwiftScan.dylib' is not ready by the time the driver is used to begin compilation of the Swift standard library. For now, disable in-process queries altogether.

On 'main', this is resolved with https://github.com/swiftlang/swift/pull/77606, which seems to be a challenge to backport to 6.0.
---
 .../Jobs/EmitSupportedFeaturesJob.swift       | 18 ++++++++-------
 .../SwiftDriver/Jobs/PrintTargetInfoJob.swift | 22 ++++++++++---------
 2 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/Sources/SwiftDriver/Jobs/EmitSupportedFeaturesJob.swift b/Sources/SwiftDriver/Jobs/EmitSupportedFeaturesJob.swift
index 1adfbd827..0c565fd8d 100644
--- a/Sources/SwiftDriver/Jobs/EmitSupportedFeaturesJob.swift
+++ b/Sources/SwiftDriver/Jobs/EmitSupportedFeaturesJob.swift
@@ -64,14 +64,16 @@ extension Driver {
                                            fileSystem: FileSystem,
                                            executor: DriverExecutor)
   throws -> Set<String> {
-    do {
-      if let supportedArgs =
-          try querySupportedCompilerArgsInProcess(of: toolchain, fileSystem: fileSystem) {
-        return supportedArgs
-      }
-    } catch {
-      diagnosticsEngine.emit(.remark_inprocess_supported_features_query_failed(error.localizedDescription))
-    }
+    // Disable in-process supported features query due to a race condition in the compiler's current
+    // build system where libSwiftScan may not be ready when building the Swift standard library.
+//    do {
+//      if let supportedArgs =
+//          try querySupportedCompilerArgsInProcess(of: toolchain, fileSystem: fileSystem) {
+//        return supportedArgs
+//      }
+//    } catch {
+//      diagnosticsEngine.emit(.remark_inprocess_supported_features_query_failed(error.localizedDescription))
+//    }
 
     // Fallback: Invoke `swift-frontend -emit-supported-features` and decode the output
     let frontendOverride = try FrontendOverride(&parsedOptions, diagnosticsEngine)
diff --git a/Sources/SwiftDriver/Jobs/PrintTargetInfoJob.swift b/Sources/SwiftDriver/Jobs/PrintTargetInfoJob.swift
index 7e1129150..900d28710 100644
--- a/Sources/SwiftDriver/Jobs/PrintTargetInfoJob.swift
+++ b/Sources/SwiftDriver/Jobs/PrintTargetInfoJob.swift
@@ -248,16 +248,18 @@ extension Driver {
                                               using: executor.resolver)
     Self.sanitizeCommandForLibScanInvocation(&command)
 
-    do {
-      if let targetInfo =
-          try Self.queryTargetInfoInProcess(of: toolchain, fileSystem: fileSystem,
-                                            workingDirectory: workingDirectory,
-                                            invocationCommand: command) {
-        return targetInfo
-      }
-    } catch {
-      diagnosticsEngine.emit(.remark_inprocess_target_info_query_failed(error.localizedDescription))
-    }
+    // Disable in-process target query due to a race condition in the compiler's current
+    // build system where libSwiftScan may not be ready when building the Swift standard library.
+//    do {
+//      if let targetInfo =
+//          try Self.queryTargetInfoInProcess(of: toolchain, fileSystem: fileSystem,
+//                                            workingDirectory: workingDirectory,
+//                                            invocationCommand: command) {
+//        return targetInfo
+//      }
+//    } catch {
+//      diagnosticsEngine.emit(.remark_inprocess_target_info_query_failed(error.localizedDescription))
+//    }
 
     // Fallback: Invoke `swift-frontend -print-target-info` and decode the output
     return try executor.execute(