Add magic symbols for concurrency.

(cherry picked from commit 5743040)

Author: varungandhi-apple

stdlib/public/Concurrency/CMakeLists.txt

@@ -100,6 +100,7 @@ add_swift_target_library(swift_Concurrency ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} I
   Deque.swift
   YieldingContinuation.swift
   ${swift_concurrency_extra_sources}
+  linker-support/magic-symbols-for-install-name.c
 
   SWIFT_MODULE_DEPENDS_LINUX Glibc
   SWIFT_MODULE_DEPENDS_FREEBSD Glibc

stdlib/public/Concurrency/linker-support/magic-symbols-for-install-name.c

@@ -0,0 +1,83 @@
+//===--- magic-symbols-for-install-name.c - Magic linker directive symbols ===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 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
+//
+//===----------------------------------------------------------------------===//
+//
+// A file containing magic symbols that instruct the linker to use a
+// different install name when targeting older OSes. This file gets
+// compiled into all of the libraries that are embedded for backward
+// deployment.
+//
+// This file is specific to the Concurrency library; there is a matching file
+// for the standard library with the same name.
+//
+//===----------------------------------------------------------------------===//
+
+#if defined(__APPLE__) && defined(__MACH__)
+
+#include <Availability.h>
+#include <TargetConditionals.h>
+#include "../../SwiftShims/Visibility.h"
+
+#define RPATH_INSTALL_NAME_DIRECTIVE_IMPL2(name, major, minor) \
+  SWIFT_RUNTIME_EXPORT const char install_name_ ## major ## _ ## minor \
+  __asm("$ld$install_name$os" #major "." #minor "$@rpath/lib" #name ".dylib"); \
+  const char install_name_ ## major ## _ ## minor = 0;
+
+#define RPATH_INSTALL_NAME_DIRECTIVE_IMPL(name, major, minor) \
+  RPATH_INSTALL_NAME_DIRECTIVE_IMPL2(name, major, minor)
+
+#define RPATH_INSTALL_NAME_DIRECTIVE(major, minor) \
+  RPATH_INSTALL_NAME_DIRECTIVE_IMPL(SWIFT_TARGET_LIBRARY_NAME, major, minor)
+
+
+#if TARGET_OS_WATCH
+  // Check watchOS first, because TARGET_OS_IPHONE includes watchOS.
+  RPATH_INSTALL_NAME_DIRECTIVE( 6, 0)
+  RPATH_INSTALL_NAME_DIRECTIVE( 6, 1)
+  RPATH_INSTALL_NAME_DIRECTIVE( 6, 2)
+  RPATH_INSTALL_NAME_DIRECTIVE( 6, 3)
+  RPATH_INSTALL_NAME_DIRECTIVE( 7, 0)
+  RPATH_INSTALL_NAME_DIRECTIVE( 7, 1)
+  RPATH_INSTALL_NAME_DIRECTIVE( 7, 2)
+  RPATH_INSTALL_NAME_DIRECTIVE( 7, 3)
+  RPATH_INSTALL_NAME_DIRECTIVE( 7, 4)
+  RPATH_INSTALL_NAME_DIRECTIVE( 7, 5)
+  RPATH_INSTALL_NAME_DIRECTIVE( 7, 6)
+#elif TARGET_OS_IPHONE
+  RPATH_INSTALL_NAME_DIRECTIVE(13, 0)
+  RPATH_INSTALL_NAME_DIRECTIVE(13, 1)
+  RPATH_INSTALL_NAME_DIRECTIVE(13, 2)
+  RPATH_INSTALL_NAME_DIRECTIVE(13, 3)
+  RPATH_INSTALL_NAME_DIRECTIVE(13, 4)
+  RPATH_INSTALL_NAME_DIRECTIVE(13, 5)
+  RPATH_INSTALL_NAME_DIRECTIVE(13, 6)
+  RPATH_INSTALL_NAME_DIRECTIVE(13, 7)
+  RPATH_INSTALL_NAME_DIRECTIVE(14, 0)
+  RPATH_INSTALL_NAME_DIRECTIVE(14, 1)
+  RPATH_INSTALL_NAME_DIRECTIVE(14, 2)
+  RPATH_INSTALL_NAME_DIRECTIVE(14, 3)
+  RPATH_INSTALL_NAME_DIRECTIVE(14, 4)
+  RPATH_INSTALL_NAME_DIRECTIVE(14, 5)
+  RPATH_INSTALL_NAME_DIRECTIVE(14, 6)
+  RPATH_INSTALL_NAME_DIRECTIVE(14, 7)
+#elif TARGET_OS_OSX
+  RPATH_INSTALL_NAME_DIRECTIVE(10, 15)
+  RPATH_INSTALL_NAME_DIRECTIVE(11,  0)
+  RPATH_INSTALL_NAME_DIRECTIVE(11,  1)
+  RPATH_INSTALL_NAME_DIRECTIVE(11,  2)
+  RPATH_INSTALL_NAME_DIRECTIVE(11,  3)
+  RPATH_INSTALL_NAME_DIRECTIVE(11,  4)
+  RPATH_INSTALL_NAME_DIRECTIVE(11,  5)
+#else
+  #error Unknown target.
+#endif
+
+#endif // defined(__APPLE__) && defined(__MACH__)