diff --git a/gcc/c-family/c-opts.cc b/gcc/c-family/c-opts.cc
index 0871eb30372..7d139a7adf3 100644
--- a/gcc/c-family/c-opts.cc
+++ b/gcc/c-family/c-opts.cc
@@ -1061,6 +1061,11 @@ c_common_post_options (const char **pfilename)
 		       warn_array_compare,
 		       warn_array_compare || deprecated_in (cxx20));
 
+  /* -Wdeprecated-variadic-comma-omission is enabled by default in C++26.  */
+  SET_OPTION_IF_UNSET (&global_options, &global_options_set,
+		       warn_deprecated_variadic_comma_omission,
+		       deprecated_in (cxx26));
+
   /* -Wtemplate-id-cdtor is enabled by default in C++20.  */
   SET_OPTION_IF_UNSET (&global_options, &global_options_set,
 		       warn_template_id_cdtor,
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 467d361bb3a..0d255561b1b 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -672,6 +672,10 @@ Wdeprecated-non-prototype
 C ObjC Var(warn_deprecated_non_prototype) Init(-1) Warning
 Warn about calls with arguments to functions declared without parameters.
 
+Wdeprecated-variadic-comma-omission
+C++ ObjC++ Var(warn_deprecated_variadic_comma_omission) Warning
+Warn about deprecated omission of comma before ... in varargs function declaration.
+
 Wdesignated-init
 C ObjC Var(warn_designated_init) Init(1) Warning
 Warn about positional initialization of structs requiring designated initializers.
diff --git a/gcc/c-family/c.opt.urls b/gcc/c-family/c.opt.urls
index 56c814e1b5c..8fbe3bd2698 100644
--- a/gcc/c-family/c.opt.urls
+++ b/gcc/c-family/c.opt.urls
@@ -310,6 +310,9 @@ UrlSuffix(gcc/C_002b_002b-Dialect-Options.html#index-Wdeprecated-literal-operato
 Wdeprecated-non-prototype
 UrlSuffix(gcc/Warning-Options.html#index-Wdeprecated-non-prototype)
 
+Wdeprecated-variadic-comma-omission
+UrlSuffix(gcc/C_002b_002b-Dialect-Options.html#index-Wdeprecated-variadic-comma-omission)
+
 Wdesignated-init
 UrlSuffix(gcc/Warning-Options.html#index-Wdesignated-init)
 
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index f519ab01464..94069d7a1fe 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -25770,6 +25770,16 @@ cp_parser_parameter_declaration_clause (cp_parser* parser,
      omitted.  */
   else if (token->type == CPP_ELLIPSIS)
     {
+      /* Deprecated by P3176R1 in C++26.  */
+      if (warn_deprecated_variadic_comma_omission)
+	{
+	  gcc_rich_location richloc (token->location);
+	  richloc.add_fixit_insert_before (", ");
+	  warning_at (&richloc, OPT_Wdeprecated_variadic_comma_omission,
+		      "omission of %<,%> before varargs %<...%> is "
+		      "deprecated in C++26");
+	}
+
       /* Consume the `...' token.  */
       cp_lexer_consume_token (parser->lexer);
       /* And remember that we saw it.  */
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 18a5754a097..fa2532f437b 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -4069,6 +4069,22 @@ string operator "" _i18n(const char*, std::size_t); // deprecated
 string operator ""_i18n(const char*, std::size_t); // preferred
 @end smallexample
 
+@opindex Wdeprecated-variadic-comma-omission
+@opindex Wno-deprecated-variadic-comma-omission
+@item -Wdeprecated-variadic-comma-omission @r{(C++ and Objective-C++ only)}
+Warn that omitting a comma before the varargs @code{...} at the end of
+a function parameter list is deprecated.  This warning is enabled by
+default in C++26, or with explicit @option{-Wdeprecated}.
+
+@smallexample
+void f1(int...); // deprecated
+void f1(int, ...); // preferred
+template <typename ...T>
+void f2(T...); // ok
+template <typename ...T>
+void f3(T......); // deprecated
+@end smallexample
+
 @opindex Welaborated-enum-base
 @opindex Wno-elaborated-enum-base
 @item -Wno-elaborated-enum-base
@@ -10348,8 +10364,9 @@ In C++, explicitly specifying @option{-Wdeprecated} also enables
 warnings about some features that are deprecated in later language
 standards, specifically @option{-Wcomma-subscript},
 @option{-Wvolatile}, @option{-Wdeprecated-enum-float-conversion},
-@option{-Wdeprecated-enum-enum-conversion}, and
-@option{-Wdeprecated-literal-operator}.
+@option{-Wdeprecated-enum-enum-conversion},
+@option{-Wdeprecated-literal-operator}, and
+@option{-Wdeprecated-variadic-comma-omission}.
 
 @opindex Wno-deprecated-declarations
 @opindex Wdeprecated-declarations
diff --git a/gcc/testsuite/g++.dg/analyzer/fd-bind-pr107783.C b/gcc/testsuite/g++.dg/analyzer/fd-bind-pr107783.C
index eb5e23c82cf..318e1486e8e 100644
--- a/gcc/testsuite/g++.dg/analyzer/fd-bind-pr107783.C
+++ b/gcc/testsuite/g++.dg/analyzer/fd-bind-pr107783.C
@@ -7,5 +7,5 @@ struct _Bind {
   _Bind(_Bind &);
 };
 template <typename _Func, typename _BoundArgs>
-_Bind bind(_Func, _BoundArgs &&...);
+_Bind bind(_Func, _BoundArgs &&, ...);
 void test01() { bind(minus(), _2, _1); }
diff --git a/gcc/testsuite/g++.dg/cpp0x/gen-attrs-33.C b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-33.C
index efb2a1ad6d0..485d349ecfc 100644
--- a/gcc/testsuite/g++.dg/cpp0x/gen-attrs-33.C
+++ b/gcc/testsuite/g++.dg/cpp0x/gen-attrs-33.C
@@ -5,7 +5,7 @@
 template <int N>
 struct T
 {
-  void foo [[gnu::format (printf,2,3)]] (char const * ...);
+  void foo [[gnu::format (printf,2,3)]] (char const * ...);	// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 };
 
 template struct T<3>;
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-const3.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-const3.C
index a1ffaddc4a7..1767dd71170 100644
--- a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-const3.C
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-const3.C
@@ -7,7 +7,7 @@ struct FF
 {
   template < class F, class ... Ts >
   void
-  operator () (F & ...)
+  operator () (F & ...)			// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
   {
     const int n = sizeof ... (Ts) + 1;
     void *mutexes[n];
diff --git a/gcc/testsuite/g++.dg/cpp0x/udlit-args-neg.C b/gcc/testsuite/g++.dg/cpp0x/udlit-args-neg.C
index 72cb4b4c4cb..27508882f85 100644
--- a/gcc/testsuite/g++.dg/cpp0x/udlit-args-neg.C
+++ b/gcc/testsuite/g++.dg/cpp0x/udlit-args-neg.C
@@ -27,6 +27,7 @@ operator ""_Foo(const char16_t *);	// { dg-error "1:.Foo operator\"\"_Foo\\(cons
 
 Foo
 operator ""_Foo(char...);	// { dg-error "1:.Foo operator\"\"_Foo\\(char, \\.\\.\\.\\). has invalid argument list" }
+				// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } .-1 }
 
 Foo
 operator ""_Foo(unsigned long long int, char);	// { dg-error "1:.Foo operator\"\"_Foo\\(long long unsigned int, char\\). has invalid argument list" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic164.C b/gcc/testsuite/g++.dg/cpp0x/variadic164.C
index 8f9cdb18c2d..a3855346f5c 100644
--- a/gcc/testsuite/g++.dg/cpp0x/variadic164.C
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic164.C
@@ -8,5 +8,5 @@ template <typename Tuple, typename... Tuples, int... ElementIndices,
           typename =
               typename tuple<slice_result<ElementIndices, Tuples...>,
                              slice_result<ElementIndices, Tuples...>...>::type> // { dg-error "parameter pack" }
-void zip_with(Tuple...);
+void zip_with(Tuple...);	// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 decltype(zip_with(0)) d;	// { dg-error "no match" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic17.C b/gcc/testsuite/g++.dg/cpp0x/variadic17.C
index d54022a7c7b..4791bb4e0fc 100644
--- a/gcc/testsuite/g++.dg/cpp0x/variadic17.C
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic17.C
@@ -2,7 +2,7 @@
 template<typename R, typename... ArgTypes>
 struct make_function_type
 {
-  typedef R type(const ArgTypes&......);
+  typedef R type(const ArgTypes&......);		// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 };
 
 template<typename T, typename U>
@@ -16,6 +16,6 @@ struct is_same<T, T> {
 };
 
 int a0[is_same<make_function_type<int>::type, int(...)>::value? 1 : -1];
-int a1[is_same<make_function_type<int, float>::type, int(const float&...)>::value? 1 : -1];
+int a1[is_same<make_function_type<int, float>::type, int(const float&...)>::value? 1 : -1];		// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 int a2[is_same<make_function_type<int, float>::type, int(const float&,...)>::value? 1 : -1];
-int a3[is_same<make_function_type<int, float, double>::type, int(const float&, double const&...)>::value? 1 : -1];
+int a3[is_same<make_function_type<int, float, double>::type, int(const float&, double const&...)>::value? 1 : -1];		// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic28.C b/gcc/testsuite/g++.dg/cpp0x/variadic28.C
index b0278613cbf..57f6d23b21e 100644
--- a/gcc/testsuite/g++.dg/cpp0x/variadic28.C
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic28.C
@@ -3,7 +3,7 @@ template<typename Signature>
 struct function_traits;
 
 template<typename R, typename... ArgTypes>
-struct function_traits<R(ArgTypes......)> {
+struct function_traits<R(ArgTypes......)> {	// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
   typedef R result_type;
 };
 
@@ -17,9 +17,9 @@ struct same_type<T, T> {
   static const bool value = true;
 };
 
-int a0[same_type<function_traits<int(double, char...)>::result_type, int>::value? 1 : -1];
+int a0[same_type<function_traits<int(double, char...)>::result_type, int>::value? 1 : -1];	// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 int a1[same_type<function_traits<int(double, char,...)>::result_type, int>::value? 1 : -1];
 int a2[same_type<function_traits<int(char,...)>::result_type, int>::value? 1 : -1];
 int a3[same_type<function_traits<int(...)>::result_type, int>::value? 1 : -1];
-int a4[same_type<function_traits<int(double x, char...)>::result_type, int>::value? 1 : -1];
-int a5[same_type<function_traits<int(double, char y...)>::result_type, int>::value? 1 : -1];
+int a4[same_type<function_traits<int(double x, char...)>::result_type, int>::value? 1 : -1];	// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
+int a5[same_type<function_traits<int(double, char y...)>::result_type, int>::value? 1 : -1];	// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
diff --git a/gcc/testsuite/g++.dg/cpp0x/vt-65790.C b/gcc/testsuite/g++.dg/cpp0x/vt-65790.C
index 477e9884304..4e899630d63 100644
--- a/gcc/testsuite/g++.dg/cpp0x/vt-65790.C
+++ b/gcc/testsuite/g++.dg/cpp0x/vt-65790.C
@@ -1,7 +1,7 @@
 // PR c++/65790
 // { dg-do compile { target c++11 } }
 
-extern "C" int printf(const char* ...);
+extern "C" int printf(const char*, ...);
 
 namespace std
 {
diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic19.C b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic19.C
index e78677de0b5..0fb873dd4f2 100644
--- a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic19.C
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic19.C
@@ -1,4 +1,4 @@
 // PR c++/86728
 // { dg-do compile { target c++14 } }
 
-auto c = [](auto x ...) { };
+auto c = [](auto x ...) { };	// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
diff --git a/gcc/testsuite/g++.dg/cpp1z/fold10.C b/gcc/testsuite/g++.dg/cpp1z/fold10.C
index 1bd39a05400..87aee5b50f2 100644
--- a/gcc/testsuite/g++.dg/cpp1z/fold10.C
+++ b/gcc/testsuite/g++.dg/cpp1z/fold10.C
@@ -4,7 +4,7 @@
 template <int...> struct seq {};
 template <bool> struct S {
     template <typename Args>
-    constexpr static void call(Args&&...) {}
+    constexpr static void call(Args&&...) {}	// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 };
 
 template <int ...Idx,typename ...Args>
diff --git a/gcc/testsuite/g++.dg/cpp23/explicit-obj-diagnostics3.C b/gcc/testsuite/g++.dg/cpp23/explicit-obj-diagnostics3.C
index f6a892eb069..4ff13af2923 100644
--- a/gcc/testsuite/g++.dg/cpp23/explicit-obj-diagnostics3.C
+++ b/gcc/testsuite/g++.dg/cpp23/explicit-obj-diagnostics3.C
@@ -24,7 +24,7 @@ void S::f12(this S s = {}) {} // { dg-error "an explicit object parameter may no
 
 struct S0 {
   template<typename Selves>
-  void f(this Selves...) {}
+  void f(this Selves...) {}	    // { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 
   template<typename Selves>
   void g(this Selves... selves) {}  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
@@ -37,7 +37,7 @@ struct S0 {
   void k(this Selves...) {}  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
 
   template<typename Selves>
-  void fd(this Selves...);
+  void fd(this Selves...);	   // { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 
   template<typename Selves>
   void gd(this Selves... selves);  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
@@ -52,7 +52,7 @@ struct S0 {
 
 struct S1 {
   template<typename Selves>
-  void f(this Selves&...) {}
+  void f(this Selves&...) {}	     // { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 
   template<typename Selves>
   void g(this Selves&... selves) {}  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
@@ -65,7 +65,7 @@ struct S1 {
   void k(this Selves&...) {}  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
 
   template<typename Selves>
-  void fd(this Selves&...);
+  void fd(this Selves&...);	    // { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 
   template<typename Selves>
   void gd(this Selves&... selves);  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
@@ -80,7 +80,7 @@ struct S1 {
 
 struct S2 {
   template<typename Selves>
-  void f(this Selves&&...) {}
+  void f(this Selves&&...) {}	      // { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 
   template<typename Selves>
   void g(this Selves&&... selves) {}  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
@@ -93,7 +93,7 @@ struct S2 {
   void k(this Selves&&...) {}  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
 
   template<typename Selves>
-  void fd(this Selves&&...);
+  void fd(this Selves&&...);	     // { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 
   template<typename Selves>
   void gd(this Selves&&... selves);  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
@@ -108,7 +108,7 @@ struct S2 {
 
 struct S3 {
   template<typename Selves>
-  void f(this Selves const&...) {}
+  void f(this Selves const&...) {}	   // { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 
   template<typename Selves>
   void g(this Selves const&... selves) {}  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
@@ -121,7 +121,7 @@ struct S3 {
   void k(this Selves const&...) {}  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
 
   template<typename Selves>
-  void fd(this Selves const&...);
+  void fd(this Selves const&...);	  // { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 
   template<typename Selves>
   void gd(this Selves const&... selves);  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
@@ -136,7 +136,7 @@ struct S3 {
 
 struct S4 {
   template<typename Selves>
-  void f(this Selves const&&...) {}
+  void f(this Selves const&&...) {}	    // { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 
   template<typename Selves>
   void g(this Selves const&&... selves) {}  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
@@ -149,7 +149,7 @@ struct S4 {
   void k(this Selves const&&...) {}  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
 
   template<typename Selves>
-  void fd(this Selves const&&...);
+  void fd(this Selves const&&...);	   // { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 
   template<typename Selves>
   void gd(this Selves const&&... selves);  // { dg-error "an explicit object parameter cannot be a function parameter pack" }
diff --git a/gcc/testsuite/g++.dg/cpp26/variadic-comma1.C b/gcc/testsuite/g++.dg/cpp26/variadic-comma1.C
new file mode 100644
index 00000000000..d5cf13fe372
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp26/variadic-comma1.C
@@ -0,0 +1,18 @@
+// P3176R1 - The Oxford variadic comma
+// { dg-do compile { target c++11 } }
+
+void f1 (int...);		// { dg-warning "omission of ',' before varargs '...' is deprecated in" "" { target c++26 } }
+#if __cplusplus >= 202002L
+void f2 (auto...);
+void f3 (auto......);		// { dg-warning "omission of ',' before varargs '...' is deprecated in" "" { target c++26 } }
+#endif
+template <typename ...T>
+void f4 (T......);		// { dg-warning "omission of ',' before varargs '...' is deprecated in" "" { target c++26 } }
+template <typename ...T>
+void f5 (T...);
+template <typename ...T>
+void f6 (T..., int...);		// { dg-warning "omission of ',' before varargs '...' is deprecated in" "" { target c++26 } }
+void
+f7 (char...)			// { dg-warning "omission of ',' before varargs '...' is deprecated in" "" { target c++26 } }
+{
+}
diff --git a/gcc/testsuite/g++.dg/cpp26/variadic-comma2.C b/gcc/testsuite/g++.dg/cpp26/variadic-comma2.C
new file mode 100644
index 00000000000..8d2e8f01bf2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp26/variadic-comma2.C
@@ -0,0 +1,19 @@
+// P3176R1 - The Oxford variadic comma
+// { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wdeprecated" }
+
+void f1 (int...);		// { dg-warning "omission of ',' before varargs '...' is deprecated in" }
+#if __cplusplus >= 202002L
+void f2 (auto...);
+void f3 (auto......);		// { dg-warning "omission of ',' before varargs '...' is deprecated in" "" { target c++20 } }
+#endif
+template <typename ...T>
+void f4 (T......);		// { dg-warning "omission of ',' before varargs '...' is deprecated in" }
+template <typename ...T>
+void f5 (T...);
+template <typename ...T>
+void f6 (T..., int...);		// { dg-warning "omission of ',' before varargs '...' is deprecated in" }
+void
+f7 (char...)			// { dg-warning "omission of ',' before varargs '...' is deprecated in" }
+{
+}
diff --git a/gcc/testsuite/g++.dg/cpp26/variadic-comma3.C b/gcc/testsuite/g++.dg/cpp26/variadic-comma3.C
new file mode 100644
index 00000000000..6413478daac
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp26/variadic-comma3.C
@@ -0,0 +1,5 @@
+// P3176R1 - The Oxford variadic comma
+// { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wno-deprecated-variadic-comma-omission" }
+
+#include "variadic-comma1.C"
diff --git a/gcc/testsuite/g++.dg/cpp26/variadic-comma4.C b/gcc/testsuite/g++.dg/cpp26/variadic-comma4.C
new file mode 100644
index 00000000000..12f0d545c84
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp26/variadic-comma4.C
@@ -0,0 +1,5 @@
+// P3176R1 - The Oxford variadic comma
+// { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wno-deprecated" }
+
+#include "variadic-comma1.C"
diff --git a/gcc/testsuite/g++.dg/cpp26/variadic-comma5.C b/gcc/testsuite/g++.dg/cpp26/variadic-comma5.C
new file mode 100644
index 00000000000..ccf3ebcab1e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp26/variadic-comma5.C
@@ -0,0 +1,19 @@
+// P3176R1 - The Oxford variadic comma
+// { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wdeprecated-variadic-comma-omission" }
+
+void f1 (int...);		// { dg-warning "omission of ',' before varargs '...' is deprecated in" }
+#if __cplusplus >= 202002L
+void f2 (auto...);
+void f3 (auto......);		// { dg-warning "omission of ',' before varargs '...' is deprecated in" "" { target c++20 } }
+#endif
+template <typename ...T>
+void f4 (T......);		// { dg-warning "omission of ',' before varargs '...' is deprecated in" }
+template <typename ...T>
+void f5 (T...);
+template <typename ...T>
+void f6 (T..., int...);		// { dg-warning "omission of ',' before varargs '...' is deprecated in" }
+void
+f7 (char...)			// { dg-warning "omission of ',' before varargs '...' is deprecated in" }
+{
+}
diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-generic10.C b/gcc/testsuite/g++.dg/cpp2a/lambda-generic10.C
index 47a87bbfbd7..7329fa8e090 100644
--- a/gcc/testsuite/g++.dg/cpp2a/lambda-generic10.C
+++ b/gcc/testsuite/g++.dg/cpp2a/lambda-generic10.C
@@ -4,7 +4,7 @@
 void sink(...);
 template <int... args> void f()
 {
-  sink ([] <int T> (int...) { return 1; }
+  sink ([] <int T> (int...) { return 1; }	// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
         .operator()<args>(args...)...); // { dg-warning "-Wmissing-template-keyword" }
 } // { dg-prune-output {expected '\)'} }
 
diff --git a/gcc/testsuite/g++.dg/ext/attrib33.C b/gcc/testsuite/g++.dg/ext/attrib33.C
index 55bfc4cadb8..a244c1a1b99 100644
--- a/gcc/testsuite/g++.dg/ext/attrib33.C
+++ b/gcc/testsuite/g++.dg/ext/attrib33.C
@@ -5,7 +5,7 @@
 template <int N>
 struct T
 {
-  void foo (char const * ...) __attribute__ ((format (printf,2,3)));
+  void foo (char const * ...) __attribute__ ((format (printf,2,3)));	// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 };
 
 template struct T<3>;
diff --git a/gcc/testsuite/g++.old-deja/g++.law/operators15.C b/gcc/testsuite/g++.old-deja/g++.law/operators15.C
index ea0e6885713..9318f158c3d 100644
--- a/gcc/testsuite/g++.old-deja/g++.law/operators15.C
+++ b/gcc/testsuite/g++.old-deja/g++.law/operators15.C
@@ -6,7 +6,7 @@
 // Subject: bug report
 // Date: Wed, 27 Jan 1993 16:37:30 -0500
 
-extern "C" int printf(const char* ...);
+extern "C" int printf(const char* ...);	// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
 
 int     delete_counter = -1;
 
diff --git a/gcc/testsuite/g++.old-deja/g++.mike/p12306.C b/gcc/testsuite/g++.old-deja/g++.mike/p12306.C
index 6309016a308..b96be33272d 100644
--- a/gcc/testsuite/g++.old-deja/g++.mike/p12306.C
+++ b/gcc/testsuite/g++.old-deja/g++.mike/p12306.C
@@ -4,7 +4,7 @@
 void *ptr1, *ptr2;
 int fail = 0;
 
-extern "C" int printf(const char *...);
+extern "C" int printf(const char *, ...);
 
 class RWSlist { };
 
diff --git a/gcc/testsuite/g++.old-deja/g++.mike/p811.C b/gcc/testsuite/g++.old-deja/g++.mike/p811.C
index 174b16e1eee..ee207151a29 100644
--- a/gcc/testsuite/g++.old-deja/g++.mike/p811.C
+++ b/gcc/testsuite/g++.old-deja/g++.mike/p811.C
@@ -305,7 +305,7 @@ class ostream : public ios
     ostream& seekp(streampos);
     ostream& seekp(streamoff, _seek_dir);
     streampos tellp();
-    ostream& form(const char *format ...);
+    ostream& form(const char *format ...);		// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
     ostream& vform(const char *format, char*  args);
 };
 
@@ -460,7 +460,7 @@ class iostream : public ios {
 	{ return ((ostream*)this)->write((char*)s, n); }
     ostream& write(const void *s, int n)
 	{ return ((ostream*)this)->write((char*)s, n); }
-    ostream& form(const char *format ...);
+    ostream& form(const char *format ...);		// { dg-warning "omission of ',' before varargs '...' is deprecated" "" { target c++26 } }
     ostream& vform(const char *format, char*  args)
 	{ return ((ostream*)this)->vform(format, args); }
     ostream& seekp(streampos pos) { return ((ostream*)this)->seekp(pos); }
diff --git a/libstdc++-v3/include/bits/refwrap.h b/libstdc++-v3/include/bits/refwrap.h
index a73cdc9c71e..00a0b644331 100644
--- a/libstdc++-v3/include/bits/refwrap.h
+++ b/libstdc++-v3/include/bits/refwrap.h
@@ -94,7 +94,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       using __vararg = false_type;					\
     };									\
   template<typename _Res, typename _Class, typename... _ArgTypes>	\
-    struct _Mem_fn_traits<_Res (_Class::*)(_ArgTypes... ...) _CV _REF>	\
+    struct _Mem_fn_traits<_Res (_Class::*)(_ArgTypes..., ...) _CV _REF>	\
     : _Mem_fn_traits_base<_Res, _CV _Class, _ArgTypes...>		\
     {									\
       using __vararg = true_type;					\
@@ -145,7 +145,8 @@ _GLIBCXX_MEM_FN_TRAITS(&& noexcept, false_type, true_type)
 
   /// Retrieve the result type for a varargs function type.
   template<typename _Res, typename... _ArgTypes _GLIBCXX_NOEXCEPT_PARM>
-    struct _Weak_result_type_impl<_Res(_ArgTypes......) _GLIBCXX_NOEXCEPT_QUAL>
+    struct _Weak_result_type_impl<_Res(_ArgTypes...,
+				       ...) _GLIBCXX_NOEXCEPT_QUAL>
     { typedef _Res result_type; };
 
   /// Retrieve the result type for a function pointer.
@@ -156,7 +157,7 @@ _GLIBCXX_MEM_FN_TRAITS(&& noexcept, false_type, true_type)
   /// Retrieve the result type for a varargs function pointer.
   template<typename _Res, typename... _ArgTypes _GLIBCXX_NOEXCEPT_PARM>
     struct
-    _Weak_result_type_impl<_Res(*)(_ArgTypes......) _GLIBCXX_NOEXCEPT_QUAL>
+    _Weak_result_type_impl<_Res(*)(_ArgTypes..., ...) _GLIBCXX_NOEXCEPT_QUAL>
     { typedef _Res result_type; };
 
   // Let _Weak_result_type_impl perform the real work.
diff --git a/libstdc++-v3/include/std/functional b/libstdc++-v3/include/std/functional
index 743defc3cb8..a39124df147 100644
--- a/libstdc++-v3/include/std/functional
+++ b/libstdc++-v3/include/std/functional
@@ -841,7 +841,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     };
 
   template<typename _Ret, typename... _Args, typename... _BoundArgs>
-    struct _Bind_check_arity<_Ret (*)(_Args......), _BoundArgs...>
+    struct _Bind_check_arity<_Ret (*)(_Args..., ...), _BoundArgs...>
     {
       static_assert(sizeof...(_BoundArgs) >= sizeof...(_Args),
                    "Wrong number of arguments for function");
diff --git a/libstdc++-v3/include/tr1/type_traits b/libstdc++-v3/include/tr1/type_traits
index 5e55802fba7..22e156ab298 100644
--- a/libstdc++-v3/include/tr1/type_traits
+++ b/libstdc++-v3/include/tr1/type_traits
@@ -235,25 +235,24 @@ namespace tr1
     struct is_function<_Res(_ArgTypes...)>
     : public true_type { };
   template<typename _Res, typename... _ArgTypes>
-    struct is_function<_Res(_ArgTypes......)>
-    : public true_type { };
+    struct is_function<_Res(_ArgTypes..., ...)> : public true_type { };
   template<typename _Res, typename... _ArgTypes>
     struct is_function<_Res(_ArgTypes...) const>
     : public true_type { };
   template<typename _Res, typename... _ArgTypes>
-    struct is_function<_Res(_ArgTypes......) const>
+    struct is_function<_Res(_ArgTypes..., ...) const>
     : public true_type { };
   template<typename _Res, typename... _ArgTypes>
     struct is_function<_Res(_ArgTypes...) volatile>
     : public true_type { };
   template<typename _Res, typename... _ArgTypes>
-    struct is_function<_Res(_ArgTypes......) volatile>
+    struct is_function<_Res(_ArgTypes..., ...) volatile>
     : public true_type { };
   template<typename _Res, typename... _ArgTypes>
     struct is_function<_Res(_ArgTypes...) const volatile>
     : public true_type { };
   template<typename _Res, typename... _ArgTypes>
-    struct is_function<_Res(_ArgTypes......) const volatile>
+    struct is_function<_Res(_ArgTypes..., ...) const volatile>
     : public true_type { };
 
   // composite type traits [4.5.2].