[wpiutil] Upgrade to LLVM 16.0.6 (#5435)

Fixes #5332.

wpiutil/src/main/native/thirdparty/llvm/include/wpi/PointerUnion.h

@@ -17,6 +17,7 @@
 
 #include "wpi/DenseMapInfo.h"
 #include "wpi/PointerIntPair.h"
+#include "wpi/Casting.h"
 #include "wpi/PointerLikeTypeTraits.h"
 #include <algorithm>
 #include <cassert>
@@ -132,6 +133,9 @@ namespace pointer_union_detail {
   };
 }
 
+// This is a forward declaration of CastInfoPointerUnionImpl
+// Refer to its definition below for further details
+template <typename... PTs> struct CastInfoPointerUnionImpl;
 /// A discriminated union of two or more pointer types, with the discriminator
 /// in the low bit of the pointer.
 ///
@@ -167,6 +171,11 @@ class PointerUnion
   using First = TypeAtIndex<0, PTs...>;
   using Base = typename PointerUnion::PointerUnionMembers;
 
+  /// This is needed to give the CastInfo implementation below access
+  /// to protected members.
+  /// Refer to its definition for further details.
+  friend struct CastInfoPointerUnionImpl<PTs...>;
+
 public:
   PointerUnion() = default;
 
@@ -179,25 +188,24 @@ public:
 
   explicit operator bool() const { return !isNull(); }
 
+  // FIXME: Replace the uses of is(), get() and dyn_cast() with
+  //        isa<T>, cast<T> and the wpi::dyn_cast<T>
+
   /// Test if the Union currently holds the type matching T.
-  template <typename T> bool is() const {
-    return this->Val.getInt() == FirstIndexOfType<T, PTs...>::value;
-  }
+  template <typename T> inline bool is() const { return isa<T>(*this); }
 
   /// Returns the value of the specified pointer type.
   ///
   /// If the specified pointer type is incorrect, assert.
-  template <typename T> T get() const {
-    assert(is<T>() && "Invalid accessor called");
-    return PointerLikeTypeTraits<T>::getFromVoidPointer(this->Val.getPointer());
+  template <typename T> inline T get() const {
+    assert(isa<T>(*this) && "Invalid accessor called");
+    return cast<T>(*this);
   }
 
   /// Returns the current pointer if it is of the specified pointer type,
   /// otherwise returns null.
-  template <typename T> T dyn_cast() const {
-    if (is<T>())
-      return get<T>();
-    return T();
+  template <typename T> inline T dyn_cast() const {
+    return wpi::dyn_cast_if_present<T>(*this);
   }
 
   /// If the union is set to the first pointer type get an address pointing to
@@ -250,6 +258,52 @@ bool operator<(PointerUnion<PTs...> lhs, PointerUnion<PTs...> rhs) {
   return lhs.getOpaqueValue() < rhs.getOpaqueValue();
 }
 
+/// We can't (at least, at this moment with C++14) declare CastInfo
+/// as a friend of PointerUnion like this:
+/// ```
+///   template<typename To>
+///   friend struct CastInfo<To, PointerUnion<PTs...>>;
+/// ```
+/// The compiler complains 'Partial specialization cannot be declared as a
+/// friend'.
+/// So we define this struct to be a bridge between CastInfo and
+/// PointerUnion.
+template <typename... PTs> struct CastInfoPointerUnionImpl {
+  using From = PointerUnion<PTs...>;
+
+  template <typename To> static inline bool isPossible(From &F) {
+    return F.Val.getInt() == FirstIndexOfType<To, PTs...>::value;
+  }
+
+  template <typename To> static To doCast(From &F) {
+    assert(isPossible<To>(F) && "cast to an incompatible type !");
+    return PointerLikeTypeTraits<To>::getFromVoidPointer(F.Val.getPointer());
+  }
+};
+
+// Specialization of CastInfo for PointerUnion
+template <typename To, typename... PTs>
+struct CastInfo<To, PointerUnion<PTs...>>
+    : public DefaultDoCastIfPossible<To, PointerUnion<PTs...>,
+                                     CastInfo<To, PointerUnion<PTs...>>> {
+  using From = PointerUnion<PTs...>;
+  using Impl = CastInfoPointerUnionImpl<PTs...>;
+
+  static inline bool isPossible(From &f) {
+    return Impl::template isPossible<To>(f);
+  }
+
+  static To doCast(From &f) { return Impl::template doCast<To>(f); }
+
+  static inline To castFailed() { return To(); }
+};
+
+template <typename To, typename... PTs>
+struct CastInfo<To, const PointerUnion<PTs...>>
+    : public ConstStrippingForwardingCast<To, const PointerUnion<PTs...>,
+                                          CastInfo<To, PointerUnion<PTs...>>> {
+};
+
 // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has
 // # low bits available = min(PT1bits,PT2bits)-1.
 template <typename ...PTs>