PR c++/71290 - 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: Same.
	* g++.dg/ext/flexarray-subst.C: Same.
	* g++.dg/ext/flexary10.C: Same.
	* g++.dg/ext/flexary11.C: Same.
	* g++.dg/ext/flexary14.C: Same.
	* g++.dg/ext/flexary16.C: Same.
	* g++.dg/ext/flexary18.C: Same.
	* g++.dg/ext/flexary19.C: Same.
	* g++.dg/ext/flexary7.C: Same.
	* gcc/testsuite/g++.dg/cpp1z/has-unique-obj-representations1.C: Same.
	* gcc/testsuite/g++.dg/ubsan/object-size-1.C: Same.
	* gcc/testsuite/obj-c++.dg/property/at-property-23.mm: Same.

From-SVN: r244910

gcc/cp/ChangeLog

+2017-01-25  Martin Sebor  <msebor@redhat.com>
+
+	PR c++/71290
+	* decl.c (grokdeclarator): Warn on flexible array members.
+
 2017-01-25  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/78896

gcc/cp/decl.c

@@ -11804,6 +11804,17 @@ 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);
 	      }

gcc/testsuite/g++.dg/cpp1z/has-unique-obj-representations1.C

 // { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wno-error=pedantic" }
 
 #define INTB (__SIZEOF_INT__ * __CHAR_BIT__)
 struct S { int i : INTB * 3 / 4; S (); };
@@ -7,7 +8,9 @@ struct U { int i : INTB * 3 / 4; int j : INTB / 4; };
 struct V { int i : INTB * 3 / 4; int j : INTB / 4 + 1; };
 struct W {};
 struct X : public W { int i; void bar (); };
-struct Y { char a[3]; char b[]; };
+struct Y {
+  char a[3]; char b[];   // { dg-warning "forbids flexible array member" }
+};
 struct Z { int a; float b; };
 struct A { int i : INTB * 2; int j; };			// { dg-warning "exceeds its type" }
 union B { long a; unsigned long b; };

gcc/testsuite/g++.dg/ext/flexarray-mangle-2.C

 // 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.

gcc/testsuite/g++.dg/ext/flexarray-mangle.C

 // 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.

gcc/testsuite/g++.dg/ext/flexarray-subst.C

 // 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;

gcc/testsuite/g++.dg/ext/flexary10.C

@@ -4,7 +4,7 @@
 
 struct A {
   int n;
-  int a [];
+  int a[];  // { dg-warning "forbids flexible array member" }
 };
 
 struct A foo (void)

gcc/testsuite/g++.dg/ext/flexary11.C

@@ -4,7 +4,7 @@
 
 struct A {
   int n;
-  char a [];
+  char a[];   // { dg-error "forbids flexible array member" }
 };
 
 void f ()

gcc/testsuite/g++.dg/ext/flexary14.C

@@ -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)
 {

gcc/testsuite/g++.dg/ext/flexary16.C

 // 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" }
   };
 };
 

gcc/testsuite/g++.dg/ext/flexary18.C

@@ -211,3 +211,5 @@ struct StructUnion9 {                       // { dg-message "in the definition"
     } b2;                                   // { dg-warning "invalid use" }
   } a2;                                     // { dg-message "next member" }
 };
+
+// { dg-prune-output "forbids flexible array member" }

gcc/testsuite/g++.dg/ext/flexary19.C

@@ -341,3 +341,4 @@ struct S35
   typedef D D2;
 };
 
+// { dg-prune-output "forbids flexible array member" }

gcc/testsuite/g++.dg/ext/flexary7.C

@@ -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 =

gcc/testsuite/g++.dg/ext/pr71290.C

+// 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." }
+};

gcc/testsuite/g++.dg/ubsan/object-size-1.C

 // { dg-do compile }
 // { dg-options "-Wpedantic -Wno-error=pedantic -fsanitize=undefined -fpermissive" }
 
-struct T { int c; char d[]; };
+struct T
+{
+  int c; char d[];   // { dg-warning "forbids flexible array member" }
+};
 
 struct T t = { 1, "a" }; // { dg-warning "initialization of a flexible array member " }
 

gcc/testsuite/obj-c++.dg/property/at-property-23.mm

@@ -14,4 +14,6 @@
 @property int a[8]; /* { dg-error "property can not be an array" } */
 @property int b:8;  /* { dg-error "expected" } */
 @property int c[];  /* { dg-error "property can not be an array" } */
+/* { dg-error "forbids flexible array member" "flexible array member" { target \
+*-*-* } .-1 } */
 @end