[clang] [clang][bytecode][NFC] Use an anonymous union in Pointer (PR #154405)

[Shafik Yaghmour via cfe-commits]

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@@ -95,31 +93,23 @@ class Pointer {
   static constexpr unsigned RootPtrMark = ~0u;
 
 public:
-  Pointer() {
-    StorageKind = Storage::Int;
-    PointeeStorage.Int.Value = 0;
-    PointeeStorage.Int.Desc = nullptr;
-  }
-  Pointer(IntPointer &&IntPtr) : StorageKind(Storage::Int) {
-    PointeeStorage.Int = std::move(IntPtr);
-  }
+  Pointer() : StorageKind(Storage::Int), Int{nullptr, 0} {}
+  Pointer(IntPointer &&IntPtr)
+      : StorageKind(Storage::Int), Int(std::move(IntPtr)) {}
   Pointer(Block *B);
   Pointer(Block *B, uint64_t BaseAndOffset);
   Pointer(const Pointer &P);
   Pointer(Pointer &&P);
   Pointer(uint64_t Address, const Descriptor *Desc, uint64_t Offset = 0)
-      : Offset(Offset), StorageKind(Storage::Int) {
-    PointeeStorage.Int.Value = Address;
-    PointeeStorage.Int.Desc = Desc;
-  }
+      : Offset(Offset), StorageKind(Storage::Int), Int{Desc, Address} {}
   Pointer(const Function *F, uint64_t Offset = 0)
-      : Offset(Offset), StorageKind(Storage::Fn) {
-    PointeeStorage.Fn = FunctionPointer(F);
+      : Offset(Offset), StorageKind(Storage::Fn), Fn(F) {
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shafik wrote:

Why do you set `Fn` twice, once in the mem-init-list and then in the body of the constructor?

https://github.com/llvm/llvm-project/pull/154405