[Concurrency] Fix runtime isolated-conformance checks with static stdlib

Most of linkers pull object files from static archives only if any
symbol from that object file is referenced, even if the object contains
a ctor code. `Setup.cpp` didn't have any symbols referenced from
other code, so it was not linked in when the concurrency runtime was
linked in statically. This commit moves the ctor code to `Task.cpp`
to ensure that it is always linked in.

Author: kateinoigakukun

Runtimes/Core/Concurrency/CMakeLists.txt

@@ -16,7 +16,6 @@ add_library(swift_Concurrency
   ExecutorImpl.cpp
   ExecutorChecks.cpp
   GlobalExecutor.cpp
-  Setup.cpp
   Task.cpp
   TaskAlloc.cpp
   TaskGroup.cpp

stdlib/public/Concurrency/CMakeLists.txt

@@ -84,7 +84,6 @@ set(SWIFT_RUNTIME_CONCURRENCY_C_SOURCES
   Error.cpp
   ExecutorBridge.cpp
   ExecutorChecks.cpp
-  Setup.cpp
   Task.cpp
   TaskAlloc.cpp
   TaskStatus.cpp

stdlib/public/Concurrency/Setup.cpp

@@ -1874,6 +1874,60 @@ static void swift_task_startOnMainActorImpl(AsyncTask* task) {
   _swift_task_setCurrent(originalTask);
 }
 
+// ==== Load-time setup code ----------------------------------------------------
+//
+// The ctor below is placed here so that it must always be linked into the final
+// image even if the libswift_Concurrency is linked in as a static library.
+
+#if !SWIFT_CONCURRENCY_EMBEDDED
+
+// Helper macros for figuring out the mangled name of a context descriptor.
+#define DESCRIPTOR_MANGLING_SUFFIX_Structure Mn
+#define DESCRIPTOR_MANGLING_SUFFIX_Class Mn
+#define DESCRIPTOR_MANGLING_SUFFIX_Enum Mn
+#define DESCRIPTOR_MANGLING_SUFFIX_Protocol Mp
+
+#define DESCRIPTOR_MANGLING_SUFFIX_(X) X
+#define DESCRIPTOR_MANGLING_SUFFIX(KIND)                                       \
+  DESCRIPTOR_MANGLING_SUFFIX_(DESCRIPTOR_MANGLING_SUFFIX_##KIND)
+
+#define DESCRIPTOR_MANGLING_(CHAR, SUFFIX) $sSc##CHAR##SUFFIX
+#define DESCRIPTOR_MANGLING(CHAR, SUFFIX) DESCRIPTOR_MANGLING_(CHAR, SUFFIX)
+
+// Declare context descriptors for all of the concurrency descriptors with
+// standard manglings.
+#define STANDARD_TYPE(KIND, MANGLING, TYPENAME)
+#define STANDARD_TYPE_CONCURRENCY(KIND, MANGLING, TYPENAME)                    \
+  extern "C" const swift::ContextDescriptor DESCRIPTOR_MANGLING(               \
+      MANGLING, DESCRIPTOR_MANGLING_SUFFIX(KIND));
+#include "swift/Demangling/StandardTypesMangling.def"
+
+// Defined in Swift, redeclared here so we can register it with the runtime.
+extern "C" SWIFT_CC(swift)
+bool _swift_task_isCurrentGlobalActor(
+    const swift::Metadata *, const swift::WitnessTable *);
+
+// Register our type descriptors with standard manglings when the concurrency
+// runtime is loaded. This allows the runtime to quickly resolve those standard
+// manglings.
+SWIFT_ALLOWED_RUNTIME_GLOBAL_CTOR_BEGIN
+__attribute__((constructor)) static void setupStandardConcurrencyDescriptors() {
+  static const swift::ConcurrencyStandardTypeDescriptors descriptors = {
+#define STANDARD_TYPE(KIND, MANGLING, TYPENAME)
+#define STANDARD_TYPE_CONCURRENCY(KIND, MANGLING, TYPENAME)                    \
+  &DESCRIPTOR_MANGLING(MANGLING, DESCRIPTOR_MANGLING_SUFFIX(KIND)),
+#include "swift/Demangling/StandardTypesMangling.def"
+  };
+  _swift_registerConcurrencyRuntime(
+      &descriptors,
+      &_swift_task_isCurrentGlobalActor);
+}
+SWIFT_ALLOWED_RUNTIME_GLOBAL_CTOR_END
+
+#endif
+
+// ==== Back-deploy hooks -------------------------------------------------------
+
 #define OVERRIDE_TASK COMPATIBILITY_OVERRIDE
 
 #ifdef SWIFT_STDLIB_SUPPORT_BACK_DEPLOYMENT