[Support] Remove AlignedCharArrayUnion from Expected and ErrorOr, NFCI. (#127407)

They were instantiated with only a single type and union-members
themselves. By putting the types directly into a union, they are still
left uninitialized by default.

Author: hahnjo

llvm/include/llvm/Support/Error.h

@@ -16,7 +16,6 @@
 #include "llvm-c/Error.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Config/abi-breaking.h"
-#include "llvm/Support/AlignOf.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -680,22 +679,22 @@ template <class T> class [[nodiscard]] Expected {
 
   storage_type *getStorage() {
     assert(!HasError && "Cannot get value when an error exists!");
-    return reinterpret_cast<storage_type *>(&TStorage);
+    return &TStorage;
   }
 
   const storage_type *getStorage() const {
     assert(!HasError && "Cannot get value when an error exists!");
-    return reinterpret_cast<const storage_type *>(&TStorage);
+    return &TStorage;
   }
 
   error_type *getErrorStorage() {
     assert(HasError && "Cannot get error when a value exists!");
-    return reinterpret_cast<error_type *>(&ErrorStorage);
+    return &ErrorStorage;
   }
 
   const error_type *getErrorStorage() const {
     assert(HasError && "Cannot get error when a value exists!");
-    return reinterpret_cast<const error_type *>(&ErrorStorage);
+    return &ErrorStorage;
   }
 
   // Used by ExpectedAsOutParameter to reset the checked flag.
@@ -727,8 +726,8 @@ template <class T> class [[nodiscard]] Expected {
   }
 
   union {
-    AlignedCharArrayUnion<storage_type> TStorage;
-    AlignedCharArrayUnion<error_type> ErrorStorage;
+    storage_type TStorage;
+    error_type ErrorStorage;
   };
   bool HasError : 1;
 #if LLVM_ENABLE_ABI_BREAKING_CHECKS

llvm/include/llvm/Support/ErrorOr.h

@@ -15,7 +15,6 @@
 #ifndef LLVM_SUPPORT_ERROROR_H
 #define LLVM_SUPPORT_ERROROR_H
 
-#include "llvm/Support/AlignOf.h"
 #include <cassert>
 #include <system_error>
 #include <type_traits>
@@ -234,26 +233,27 @@ class ErrorOr {
 
   storage_type *getStorage() {
     assert(!HasError && "Cannot get value when an error exists!");
-    return reinterpret_cast<storage_type *>(&TStorage);
+    return &TStorage;
   }
 
   const storage_type *getStorage() const {
     assert(!HasError && "Cannot get value when an error exists!");
-    return reinterpret_cast<const storage_type *>(&TStorage);
+    return &TStorage;
   }
 
   std::error_code *getErrorStorage() {
     assert(HasError && "Cannot get error when a value exists!");
-    return reinterpret_cast<std::error_code *>(&ErrorStorage);
+    return &ErrorStorage;
   }
 
   const std::error_code *getErrorStorage() const {
-    return const_cast<ErrorOr<T> *>(this)->getErrorStorage();
+    assert(HasError && "Cannot get error when a value exists!");
+    return &ErrorStorage;
   }
 
   union {
-    AlignedCharArrayUnion<storage_type> TStorage;
-    AlignedCharArrayUnion<std::error_code> ErrorStorage;
+    storage_type TStorage;
+    std::error_code ErrorStorage;
   };
   bool HasError : 1;
 };

llvm/include/llvm/Support/TrailingObjects.h

@@ -46,7 +46,6 @@
 #ifndef LLVM_SUPPORT_TRAILINGOBJECTS_H
 #define LLVM_SUPPORT_TRAILINGOBJECTS_H
 
-#include "llvm/Support/AlignOf.h"
 #include "llvm/Support/Alignment.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/MathExtras.h"