Unpoison memory before reinterpret

This commit unpoisons memory before using memory as different types/before memset.
Buildobts were failing and therefore short string annotations were turned off.
Here: #78627

This commit unpoisons memory before debug "scribble across the rest of the storage",
as well as before reinterpret cast of an union.

Author: Advenam Tacet

llvm/include/llvm/ADT/FunctionExtras.h

@@ -319,6 +319,9 @@ template <typename ReturnT, typename... ParamTs> class UniqueFunctionBase {
 
 #ifndef NDEBUG
     // In debug builds, we also scribble across the rest of the storage.
+#ifndef _LIBCPP_HAS_NO_ASAN
+    __asan_unpoison_memory_region(RHS.getInlineStorage(), InlineStorageSize);
+#endif
     memset(RHS.getInlineStorage(), 0xAD, InlineStorageSize);
 #endif
   }

llvm/include/llvm/Support/JSON.h

@@ -482,6 +482,9 @@ class Value {
   friend class Object;
 
   template <typename T, typename... U> void create(U &&... V) {
+#ifndef _LIBCPP_HAS_NO_ASAN
+    __asan_unpoison_memory_region(&Union, sizeof(T));
+#endif
     new (reinterpret_cast<T *>(&Union)) T(std::forward<U>(V)...);
   }
   template <typename T> T &as() const {