diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1e11fb278db..4946e3b05c8 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2006-02-07  Dirk Mueller  <dmueller@suse.com>
+
+	* c.opt: C++ frontend supports -Wdiv-by-zero.
+	* c-opts.c (c_common_handle_option): Remove dead case.
+
 2006-02-07  Eric Botcazou  <ebotcazou@libertysurf.fr>
 
 	* configure.ac (TLS assembler check): Do not enable TLS by
diff --git a/gcc/c-opts.c b/gcc/c-opts.c
index 8c5827a3959..34fc6b9b0ad 100644
--- a/gcc/c-opts.c
+++ b/gcc/c-opts.c
@@ -431,10 +431,6 @@ c_common_handle_option (size_t scode, const char *arg, int value)
       cpp_opts->warn_deprecated = value;
       break;
 
-    case OPT_Wdiv_by_zero:
-      warn_div_by_zero = value;
-      break;
-
     case OPT_Wendif_labels:
       cpp_opts->warn_endif_labels = value;
       break;
diff --git a/gcc/c.opt b/gcc/c.opt
index 4ce9b9fed89..a841d528132 100644
--- a/gcc/c.opt
+++ b/gcc/c.opt
@@ -166,7 +166,7 @@ C++ ObjC++ Var(warn_deprecated) Init(1)
 Warn about deprecated compiler features
 
 Wdiv-by-zero
-C ObjC Var(warn_div_by_zero) Init(1)
+C ObjC C++ Var(warn_div_by_zero) Init(1)
 Warn about compile-time integer division by zero
 
 Weffc++
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index cdfeaf33d1e..8b0e9fc444b 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2006-02-07  Dirk Mueller  <dmueller@suse.com>
+
+	* typeck.c (build_binary_op): Annotate div-by-zero
+	warnings to make -Wno-div-by-zero have an effect.
+
 2006-02-07  Mark Mitchell  <mark@codesourcery.com>
 
 	PR c++/9737
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 1fb3cbf7915..adac22716fb 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -2954,9 +2954,9 @@ build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
 	      || code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE))
 	{
 	  if (TREE_CODE (op1) == INTEGER_CST && integer_zerop (op1))
-	    warning (0, "division by zero in %<%E / 0%>", op0);
+	    warning (OPT_Wdiv_by_zero, "division by zero in %<%E / 0%>", op0);
 	  else if (TREE_CODE (op1) == REAL_CST && real_zerop (op1))
-	    warning (0, "division by zero in %<%E / 0.%>", op0);
+	    warning (OPT_Wdiv_by_zero, "division by zero in %<%E / 0.%>", op0);
 
 	  if (code0 == COMPLEX_TYPE || code0 == VECTOR_TYPE)
 	    code0 = TREE_CODE (TREE_TYPE (TREE_TYPE (op0)));
@@ -2991,9 +2991,9 @@ build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
     case TRUNC_MOD_EXPR:
     case FLOOR_MOD_EXPR:
       if (code1 == INTEGER_TYPE && integer_zerop (op1))
-	warning (0, "division by zero in %<%E %% 0%>", op0);
+	warning (OPT_Wdiv_by_zero, "division by zero in %<%E %% 0%>", op0);
       else if (code1 == REAL_TYPE && real_zerop (op1))
-	warning (0, "division by zero in %<%E %% 0.%>", op0);
+	warning (OPT_Wdiv_by_zero, "division by zero in %<%E %% 0.%>", op0);
 
       if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
 	{
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c9e44af3d86..e9fb7d1b616 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2006-02-07  Dirk Mueller  <dmueller@suse.com>
+
+	g++.dg/warn/Wdiv-by-zero.C: New test.
+	g++.dg/warn/Wno-div-by-zero.C: New.
+
 2006-02-07  Jeff Law  <law@redhat.com>
 
 	* gcc.dg/tree-ssa/vrp01.c: Update dumpfile names now that we have
diff --git a/gcc/testsuite/g++.dg/warn/Wdiv-by-zero.C b/gcc/testsuite/g++.dg/warn/Wdiv-by-zero.C
new file mode 100644
index 00000000000..7dc77667c22
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wdiv-by-zero.C
@@ -0,0 +1,7 @@
+// test that division by zero warnings are enabled by default
+int breakme()
+{
+  int x = 0;
+  x /= 0;          // { dg-warning "division by" }
+  return x;
+}
diff --git a/gcc/testsuite/g++.dg/warn/Wno-div-by-zero.C b/gcc/testsuite/g++.dg/warn/Wno-div-by-zero.C
new file mode 100644
index 00000000000..937628ee924
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wno-div-by-zero.C
@@ -0,0 +1,8 @@
+// { dg-options "-Wno-div-by-zero" }
+
+int breakme()
+{
+  int x = 0;
+  x /= 0;
+  return x;
+}