stdlib: repair the Windows runtime build

Fix syntactic issues in the swift runtime build from the recent TLS changes.
Move the helper definitions into the TLS stubs rather than emitting them
everywhere.  This allows the runtime to build again on Windows.

Author: compnerd

stdlib/public/runtime/ThreadLocalStorage.h

@@ -88,19 +88,6 @@ typedef unsigned long __swift_thread_key_t;
 static_assert(std::is_same<__swift_thread_key_t, DWORD>::value,
               "__swift_thread_key_t is not a DWORD");
 
-#  if defined(_M_IX86)
-typedef stdcall void (*__swift_thread_key_destructor)(void *)
-#  else
-typedef void (*__swift_thread_key_destructor)(void *)
-#  endif
-
-static inline
-_stdlib_thread_key_create(__swift_thread_key_t * _Nonnull key,
-                          __swift_thread_key_destructor _Nullable destructor) {
-  *key = FlsAlloc(destroyTLS_CCAdjustmentThunk);
-  return *key != FLS_OUT_OF_INDEXES;
-}
-
 #  define SWIFT_THREAD_KEY_CREATE _stdlib_thread_key_create
 #  define SWIFT_THREAD_GETSPECIFIC FlsGetValue
 #  define SWIFT_THREAD_SETSPECIFIC(key, value) (FlsSetValue(key, value) == TRUE)

stdlib/public/stubs/ThreadLocalStorage.cpp

@@ -19,9 +19,39 @@
 
 SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_API
 void _stdlib_destroyTLS(void *);
+
 SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_API
 void *_stdlib_createTLS(void);
 
+#ifndef SWIFT_THREAD_GETSPECIFIC
+
+# if defined(_WIN32) && !defined(__CYGWIN__)
+
+#  if defined(_M_IX86)
+typedef __stdcall void (*__swift_thread_key_destructor)(void *);
+#  else
+typedef void (*__swift_thread_key_destructor)(void *);
+#  endif
+
+static void
+#if defined(_M_IX86)
+__stdcall
+#endif
+destroyTLS_CCAdjustmentThunk(void *ptr) {
+  _stdlib_destroyTLS(ptr);
+}
+
+static inline int
+_stdlib_thread_key_create(__swift_thread_key_t * _Nonnull key,
+                          __swift_thread_key_destructor _Nullable destructor) {
+  *key = FlsAlloc(destroyTLS_CCAdjustmentThunk);
+  return *key != FLS_OUT_OF_INDEXES;
+}
+
+# endif
+
+#endif
+
 #if SWIFT_TLS_HAS_RESERVED_PTHREAD_SPECIFIC
 
 SWIFT_RUNTIME_STDLIB_INTERNAL
@@ -52,7 +82,8 @@ SWIFT_RUNTIME_STDLIB_INTERNAL
 void *
 _swift_stdlib_threadLocalStorageGet(void) {
   static swift::OnceToken_t token;
-  static pthread_key_t key;
+  static __swift_thread_key_t key;
+
   SWIFT_ONCE_F(token, [](void *) {
     int result = SWIFT_THREAD_KEY_CREATE(&key, [](void *pointer) {
       _stdlib_destroyTLS(pointer);
@@ -61,7 +92,7 @@ _swift_stdlib_threadLocalStorageGet(void) {
       swift::fatalError(0, "couldn't create pthread key for stdlib TLS: %s\n",
                         std::strerror(result));
   }, nullptr);
-  
+
   void *value = SWIFT_THREAD_GETSPECIFIC(key);
   if (!value) {
     value = _stdlib_createTLS();