invoke.texi: Document -Wdelete-non-virtual-dtor.

	* doc/invoke.texi: Document -Wdelete-non-virtual-dtor.

c-family:
	* c.opt: Add -Wdelete-non-virtual-dtor.
	* c-opts.c (c_common_handle_option): Include it in -Wall.

cp:
	* init.c (build_delete): Warn when deleting type with non-virtual
	destructor.

testsuite:
	* testsuite/g++.dg/warn/delete-non-virtual-dtor.C: New.

From-SVN: r174643

gcc/ChangeLog

+2011-06-04  Jonathan Wakely  <jwakely.gcc@gmail.com>
+
+	* doc/invoke.texi: Document -Wdelete-non-virtual-dtor.
+
 2011-06-04  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/49281

gcc/c-family/ChangeLog

+2011-06-02  Jonathan Wakely  <jwakely.gcc@gmail.com>
+
+	* c.opt: Add -Wdelete-non-virtual-dtor.
+	* c-opts.c (c_common_handle_option): Include it in -Wall.
+
 2011-05-30  Nathan Froyd  <froydnj@gcc.gnu.org>
 
 	PR bootstrap/49190

gcc/c-family/c-opts.c

@@ -405,6 +405,7 @@ c_common_handle_option (size_t scode, const char *arg, int value,
           warn_sign_compare = value;
 	  warn_reorder = value;
           warn_cxx0x_compat = value;
+          warn_delnonvdtor = value;
 	}
 
       cpp_opts->warn_trigraphs = value;

gcc/c-family/c.opt

@@ -331,6 +331,10 @@ Wdeclaration-after-statement
 C ObjC Var(warn_declaration_after_statement) Warning
 Warn when a declaration is found after a statement
 
+Wdelete-non-virtual-dtor
+C++ ObjC++ Var(warn_delnonvdtor) Warning
+Warn about deleting polymorphic objects with non-virtual destructors
+
 Wdeprecated
 C C++ ObjC ObjC++ Var(warn_deprecated) Init(1) Warning
 Warn if a deprecated compiler feature, class, method, or field is used

gcc/cp/ChangeLog

+2011-06-04  Jonathan Wakely  <jwakely.gcc@gmail.com>
+
+	* init.c (build_delete): Warn when deleting type with non-virtual
+	destructor.
+
 2011-06-03  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/49276

gcc/cp/init.c

@@ -3421,6 +3421,25 @@ build_delete (tree type, tree addr, special_function_kind auto_delete,
 		}
 	      complete_p = false;
 	    }
+	  else if (warn_delnonvdtor && MAYBE_CLASS_TYPE_P (type)
+		   && !CLASSTYPE_FINAL (type) && TYPE_POLYMORPHIC_P (type))
+	    {
+	      tree dtor;
+	      dtor = CLASSTYPE_DESTRUCTORS (type);
+	      if (!dtor || !DECL_VINDEX (dtor))
+		{
+		  if (CLASSTYPE_PURE_VIRTUALS (type))
+		    warning (OPT_Wdelete_non_virtual_dtor,
+			     "deleting object of abstract class type %qT"
+			     " which has non-virtual destructor"
+			     " will cause undefined behaviour", type);
+		  else
+		    warning (OPT_Wdelete_non_virtual_dtor,
+			     "deleting object of polymorphic class type %qT"
+			     " which has non-virtual destructor"
+			     " might cause undefined behaviour", type);
+		}
+	    }
 	}
       if (VOID_TYPE_P (type) || !complete_p || !MAYBE_CLASS_TYPE_P (type))
 	/* Call the builtin operator delete.  */

gcc/doc/invoke.texi

@@ -2331,6 +2331,15 @@ Warn when a class seems unusable because all the constructors or
 destructors in that class are private, and it has neither friends nor
 public static member functions.
 
+@item -Wdelete-non-virtual-dtor @r{(C++ and Objective-C++ only)}
+@opindex Wdelete-non-virtual-dtor
+@opindex Wno-delete-non-virtual-dtor
+Warn when @samp{delete} is used to destroy an instance of a class which
+has virtual functions and non-virtual destructor. It is unsafe to delete
+an instance of a derived class through a pointer to a base class if the
+base class does not have a virtual destructor.  This warning is enabled
+by @option{-Wall}.
+
 @item -Wnoexcept @r{(C++ and Objective-C++ only)}
 @opindex Wnoexcept
 @opindex Wno-noexcept

gcc/testsuite/ChangeLog

 2011-06-04  Jonathan Wakely  <jwakely.gcc@gmail.com>
 
+	* testsuite/g++.dg/warn/delete-non-virtual-dtor.C: New.
+
+2011-06-04  Jonathan Wakely  <jwakely.gcc@gmail.com>
+
 	PR c++/33840
 	* g++.dg/diagnostic/bitfld2.C: New.
 

gcc/testsuite/g++.dg/warn/delete-non-virtual-dtor.C

+// { dg-options "-std=gnu++0x -Wdelete-non-virtual-dtor" }
+// { dg-do compile }
+
+struct polyBase { virtual void f(); };
+
+void f(polyBase* p, polyBase* arr)
+{
+  delete p;      // { dg-warning "non-virtual destructor might" }
+  delete [] arr;
+}
+
+struct polyDerived : polyBase { };
+
+void f(polyDerived* p, polyDerived* arr)
+{
+  delete p;      // { dg-warning "non-virtual destructor might" }
+  delete [] arr;
+}
+
+struct absDerived : polyBase { virtual void g() = 0; };
+
+void f(absDerived* p, absDerived* arr)
+{
+  delete p;      // { dg-warning "non-virtual destructor will" }
+  delete [] arr;
+}
+
+struct finalDerived final : polyBase { };
+
+void f(finalDerived* p, finalDerived* arr)
+{
+  delete p;      // no error for final classes
+  delete [] arr;
+}
+
+struct safeBase { virtual ~safeBase(); };
+struct safeDerived : safeBase { virtual void f(); };
+
+void f(safeDerived* p, safeDerived* arr)
+{
+  delete p;      // no error because base has virtual dtor
+  delete [] arr;
+}
+