PR c++/71290 - [6/7 Regression] Flexible array member is not diagnosed with -pedantic

gcc/cp/ChangeLog:

	PR c++/71290
	* decl.c (grokdeclarator): Warn on flexible array members.

gcc/testsuite/ChangeLog:

	PR c++/71290
	* g++.dg/ext/flexarray-mangle-2.C: Adjust.
	* g++.dg/ext/flexarray-mangle.C: Adjust.
	* g++.dg/ext/flexarray-subst.C: Adjust.
	* g++.dg/ext/flexary10.C: Adjust.
	* g++.dg/ext/flexary11.C: Adjust.
	* g++.dg/ext/flexary14.C: Adjust.
	* g++.dg/ext/flexary16.C: Adjust.
	* g++.dg/ext/flexary18.C: Adjust.
	* g++.dg/ext/flexary19.C: Adjust.
	* g++.dg/ext/flexary7.C: Adjust.
	* g++.dg/ext/pr71290.C: New test.

Index: gcc/cp/decl.c
===================================================================
--- gcc/cp/decl.c	(revision 244844)
+++ gcc/cp/decl.c	(working copy)
@@ -11798,6 +11798,17 @@ grokdeclarator (const cp_declarator *declarator,
 	      }
 	    else 
 	      {
+		/* Array is a flexible member.  */
+		if (in_system_header_at (input_location))
+		  /* Do not warn flexible them in system headers because glibc
+		     uses them.  */;
+		else if (name)
+		  pedwarn (input_location, OPT_Wpedantic,
+			   "ISO C++ forbids flexible array member %<%s%>", name);
+		else
+		  pedwarn (input_location, OPT_Wpedantic,
+			   "ISO C++ forbids flexible array members");
+
 		/* Flexible array member has a null domain.  */
 		type = build_cplus_array_type (TREE_TYPE (type), NULL_TREE);
 	      }
Index: gcc/testsuite/g++.dg/ext/flexarray-mangle-2.C
===================================================================
--- gcc/testsuite/g++.dg/ext/flexarray-mangle-2.C	(revision 244844)
+++ gcc/testsuite/g++.dg/ext/flexarray-mangle-2.C	(working copy)
@@ -1,9 +1,10 @@
 // PR c++/69277 - [6 Regression] ICE mangling a flexible array member
 // { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wno-error=pedantic" }
 
 struct A {
   int n;
-  char a [];
+  char a[];   // { dg-warning "forbids flexible array member" }
 };
 
 // Declare but do not define function templates.
Index: gcc/testsuite/g++.dg/ext/flexarray-mangle.C
===================================================================
--- gcc/testsuite/g++.dg/ext/flexarray-mangle.C	(revision 244844)
+++ gcc/testsuite/g++.dg/ext/flexarray-mangle.C	(working copy)
@@ -1,9 +1,10 @@
 // PR c++/69277 - [6 Regression] ICE mangling a flexible array member
 // { dg-do compile }
+// { dg-additional-options "-Wno-error=pedantic" }
 
 struct A {
   int n;
-  char a [];
+  char a[];   // { dg-warning "forbids flexible array member" }
 };
 
 // Declare but do not define function templates.
Index: gcc/testsuite/g++.dg/ext/flexarray-subst.C
===================================================================
--- gcc/testsuite/g++.dg/ext/flexarray-subst.C	(revision 244844)
+++ gcc/testsuite/g++.dg/ext/flexarray-subst.C	(working copy)
@@ -1,8 +1,12 @@
 // PR c++/69251 - [6 Regression] ICE (segmentation fault) in unify_array_domain
 // on i686-linux-gnu
 // { dg-do compile }
+// { dg-additional-options "-Wno-error=pedantic" }
 
-struct A { int n; char a[]; };
+struct A {
+  int n;
+  char a[];   // { dg-warning "forbids flexible array member" }
+};
 
 template <class>
 struct B;
Index: gcc/testsuite/g++.dg/ext/flexary10.C
===================================================================
--- gcc/testsuite/g++.dg/ext/flexary10.C	(revision 244844)
+++ gcc/testsuite/g++.dg/ext/flexary10.C	(working copy)
@@ -4,7 +4,7 @@
 
 struct A {
   int n;
-  int a [];
+  int a[];  // { dg-warning "forbids flexible array member" }
 };
 
 struct A foo (void)
Index: gcc/testsuite/g++.dg/ext/flexary11.C
===================================================================
--- gcc/testsuite/g++.dg/ext/flexary11.C	(revision 244844)
+++ gcc/testsuite/g++.dg/ext/flexary11.C	(working copy)
@@ -4,7 +4,7 @@
 
 struct A {
   int n;
-  char a [];
+  char a[];   // { dg-error "forbids flexible array member" }
 };
 
 void f ()
Index: gcc/testsuite/g++.dg/ext/flexary14.C
===================================================================
--- gcc/testsuite/g++.dg/ext/flexary14.C	(revision 244844)
+++ gcc/testsuite/g++.dg/ext/flexary14.C	(working copy)
@@ -9,7 +9,9 @@ struct A<T[]> { typedef int X; };
 
 template <class T> int foo (T&, typename A<T>::X = 0) { return 0; }
 
-struct B { int n, a[]; };
+struct B {
+  int n, a[];     // { dg-error "forbids flexible array member" }
+};
 
 void bar (B *b)
 {
Index: gcc/testsuite/g++.dg/ext/flexary16.C
===================================================================
--- gcc/testsuite/g++.dg/ext/flexary16.C	(revision 244844)
+++ gcc/testsuite/g++.dg/ext/flexary16.C	(working copy)
@@ -1,6 +1,7 @@
 // PR c++/71147 - [6 Regression] Flexible array member wrongly rejected
 //   in template
 // { dg-do compile }
+// { dg-options "-Wpedantic -Wno-error=pedantic" }
 
 template <typename>
 struct container
@@ -11,7 +12,7 @@ struct container
 
   struct incomplete {
     int x;
-    elem array[];
+    elem array[];  // { dg-warning "forbids flexible array member" }
   };
 };
 
@@ -26,7 +27,7 @@ struct D: container<T>
 {
   struct S {
     int x;
-    typename container<T>::elem array[];
+    typename container<T>::elem array[];  // { dg-warning "forbids flexible array member" }
   };
 };
 
Index: gcc/testsuite/g++.dg/ext/flexary18.C
===================================================================
--- gcc/testsuite/g++.dg/ext/flexary18.C	(revision 244844)
+++ gcc/testsuite/g++.dg/ext/flexary18.C	(working copy)
@@ -211,3 +211,5 @@ struct StructUnion9 {                       // { d
     } b2;                                   // { dg-warning "invalid use" }
   } a2;                                     // { dg-message "next member" }
 };
+
+// { dg-prune-output "forbids flexible array member" }
Index: gcc/testsuite/g++.dg/ext/flexary19.C
===================================================================
--- gcc/testsuite/g++.dg/ext/flexary19.C	(revision 244844)
+++ gcc/testsuite/g++.dg/ext/flexary19.C	(working copy)
@@ -341,3 +341,4 @@ struct S35
   typedef D D2;
 };
 
+// { dg-prune-output "forbids flexible array member" }
Index: gcc/testsuite/g++.dg/ext/flexary7.C
===================================================================
--- gcc/testsuite/g++.dg/ext/flexary7.C	(revision 244844)
+++ gcc/testsuite/g++.dg/ext/flexary7.C	(working copy)
@@ -5,7 +5,7 @@
 
 struct FlexChar {
     int n;
-    char a[];
+    char a[];       // { dg-warning "forbids flexible array member" }
 };
 
 struct FlexChar ac =
@@ -18,7 +18,7 @@ typedef __WCHAR_TYPE__ wchar_t;
 
 struct FlexWchar {
     int n;
-    wchar_t a[];
+    wchar_t a[];    // { dg-warning "forbids flexible array member" }
 };
 
 struct FlexWchar awc =
@@ -27,7 +27,7 @@ struct FlexWchar awc =
 
 struct FlexInt {
     int n;
-    int a[];
+    int a[];        // { dg-warning "forbids flexible array member" }
 };
 
 // Verify that no warning is issued for the case when a flexible array
@@ -48,7 +48,7 @@ struct FlexInt ai2 =
 template <class T>
 struct FlexT {
     int n;
-    T a[];
+    T a[];          // { dg-warning "forbids flexible array member" }
 };
 
 struct FlexT<char> atc =
Index: gcc/testsuite/g++.dg/ext/pr71290.C
===================================================================
--- gcc/testsuite/g++.dg/ext/pr71290.C	(revision 0)
+++ gcc/testsuite/g++.dg/ext/pr71290.C	(working copy)
@@ -0,0 +1,17 @@
+// PR c++/71290 - [6/7 Regression] Flexible array member is not diagnosed
+// with -pedantic
+
+// { dg-do compile }s
+// { dg-options "-Wall -Wpedantic" }
+
+struct A
+{
+  int i;
+  int arr[];   // { dg-warning "forbids flexible array member .arr." }
+};
+
+template <class T>
+struct B {
+  T n;
+  T a[];       // { dg-warning "forbids flexible array member .a." }
+};