Merge pull request #38088 from DougGregor/concurrency-link-compatibility-5.5

Introduce fake symbols that were present with the old concurrency ABI.

Author: tkremenek

stdlib/public/Concurrency/CMakeLists.txt

@@ -57,6 +57,7 @@ add_swift_target_library(swift_Concurrency ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} I
   AsyncThrowingMapSequence.swift
   AsyncThrowingPrefixWhileSequence.swift
   GlobalActor.swift
+  LinkCompatibilityShims.cpp
   MainActor.swift
   PartialAsyncTask.swift
   SourceCompatibilityShims.swift

stdlib/public/Concurrency/LinkCompatibilityShims.cpp

@@ -0,0 +1,26 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2020 - 2021 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+// This file provides link compatibility shims to work through some ABI
+// changes.
+//===----------------------------------------------------------------------===//
+#include "swift/Runtime/Config.h"
+
+#define OLD_SYMBOL(NAME) \
+  SWIFT_EXPORT_FROM(swift_Concurrency) extern "C" void const * const NAME = nullptr;
+
+OLD_SYMBOL($ss4TaskV6HandleVMn)
+OLD_SYMBOL($ss4TaskV8PriorityOMa)
+OLD_SYMBOL($ss4TaskV8PriorityO11unspecifiedyA2DmFWC)
+OLD_SYMBOL($ss6detach8priority9operations4TaskV6HandleVy_xs5NeverOGAE8PriorityO_xyYaYbcntlF)
+OLD_SYMBOL($ss6detach8priority9operations4TaskV6HandleVy_xs5NeverOGAE8PriorityO_xyYaYbcntlFfA_)
+OLD_SYMBOL($ss18UnsafeContinuationVMn)
+