re PR c++/20681 (wrong "control reaches" warning with switches)

	PR c++/20681
	* semantics.c (finish_break_stmt): Avoid adding an unreachable
	BREAK_STMT.

From-SVN: r183161

gcc/cp/ChangeLog

 2012-01-13  Jason Merrill  <jason@redhat.com>
 
+	PR c++/20681
+	* semantics.c (finish_break_stmt): Avoid adding an unreachable
+	BREAK_STMT.
+
 	PR c++/51813
 	* decl2.c (constrain_visibility): Clear DECL_VISIBILITY_SPECIFIED
 	when reducing the visibility.

gcc/cp/semantics.c

@@ -995,6 +995,15 @@ finish_range_for_decl (tree range_for_stmt, tree decl, tree expr)
 tree
 finish_break_stmt (void)
 {
+  /* In switch statements break is sometimes stylistically used after
+     a return statement.  This can lead to spurious warnings about
+     control reaching the end of a non-void function when it is
+     inlined.  Note that we are calling block_may_fallthru with
+     language specific tree nodes; this works because
+     block_may_fallthru returns true when given something it does not
+     understand.  */
+  if (!block_may_fallthru (cur_stmt_list))
+    return void_zero_node;
   return add_stmt (build_stmt (input_location, BREAK_STMT));
 }
 

gcc/testsuite/ChangeLog

+2012-01-13  Jason Merrill  <jason@redhat.com>
+
+	PR c++/20681
+	* g++.dg/warn/Wreturn-type-7.C: New.
+
 2012-01-13  Georg-Johann Lay  <avr@gjlay.de>
 
 	* gcc.c-torture/execute/20120111-1.c: Fix wrong int = int32_t

gcc/testsuite/g++.dg/warn/Wreturn-type-7.C

+// PR c++/20681
+// { dg-options -Wreturn-type }
+
+struct a{~a();a();};
+int GetMetaCombination (int a2)
+{
+  a bi;
+  switch (a2)
+  {
+    case 1:
+      return 18;
+      break;//removing this works around the warning
+    default:
+      return 0;
+  }
+}