Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -55,6 +55,8 @@
 -----------------------------------------
 - Clang won't search for coroutine_traits in std::experimental namespace any more.
   Clang will only search for std::coroutine_traits for coroutines then.
+- Clang no longer allows dereferencing of a ``void*`` as an extension. Clang 16
+  converted this to a warning-as-default-error as well as a SFINAE error.
 
 ABI Changes in This Version
 ---------------------------
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -6981,9 +6981,8 @@
 def ext_typecheck_indirection_through_void_pointer : ExtWarn<
   "ISO C does not allow indirection on operand of type %0">,
   InGroup<VoidPointerDeref>;
-def ext_typecheck_indirection_through_void_pointer_cpp
-    : ExtWarn<"ISO C++ does not allow indirection on operand of type %0">,
-      InGroup<VoidPointerDeref>, DefaultError, SFINAEFailure;
+def err_typecheck_indirection_through_void_pointer_cpp
+    : Error<"ISO C++ does not allow indirection on operand of type %0">;
 def warn_indirection_through_null : Warning<
   "indirection of non-volatile null pointer will be deleted, not trap">,
   InGroup<NullDereference>;
Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -14957,7 +14957,7 @@
     //   be a pointer to an object type, or a pointer to a function type
     LangOptions LO = S.getLangOpts();
     if (LO.CPlusPlus)
-      S.Diag(OpLoc, diag::ext_typecheck_indirection_through_void_pointer_cpp)
+      S.Diag(OpLoc, diag::err_typecheck_indirection_through_void_pointer_cpp)
           << OpTy << Op->getSourceRange();
     else if (!(LO.C99 && IsAfterAmp) && !S.isUnevaluatedContext())
       S.Diag(OpLoc, diag::ext_typecheck_indirection_through_void_pointer)
Index: clang/test/SemaCXX/disallow_void_deref.cpp
===================================================================
--- clang/test/SemaCXX/disallow_void_deref.cpp
+++ clang/test/SemaCXX/disallow_void_deref.cpp
@@ -1,8 +1,7 @@
-// RUN: %clang_cc1 -fsyntax-only -verify=enabled,sfinae -std=c++20 %s
-// RUN: %clang_cc1 -fsyntax-only -verify=sfinae -std=c++20 -Wno-void-ptr-dereference %s
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++20 %s
 
 void f(void* p) {
-  (void)*p; // enabled-error{{ISO C++ does not allow indirection on operand of type 'void *'}}
+  (void)*p; // expected-error{{ISO C++ does not allow indirection on operand of type 'void *'}}
 }
 
 template<class T>
@@ -11,6 +10,6 @@
 };
 
 static_assert(deref<void*>);
-// sfinae-error@-1{{static assertion failed}}
-// sfinae-note@-2{{because 'void *' does not satisfy 'deref'}}
-// sfinae-note@#FAILED_REQ{{because '*t' would be invalid: ISO C++ does not allow indirection on operand of type 'void *'}}
+// expected-error@-1{{static assertion failed}}
+// expected-note@-2{{because 'void *' does not satisfy 'deref'}}
+// expected-note@#FAILED_REQ{{because '*t' would be invalid: ISO C++ does not allow indirection on operand of type 'void *'}}