[PATCH] Set expr loc safely (PR c++/58516)

[Marek Polacek]

I admit I haven't spent much time on this, but it seems we should just
check whether we can set the expr location before actually setting it...

Regtested/bootstrapped on x86_64-linux, ok for trunk?

2013-09-24  Marek Polacek  <pola...@redhat.com>

        PR c++/58516
cp/
        * semantics.c (finish_transaction_stmt): Set location only when the
        expression can have location.

testsuite/
        * g++.dg/tm/pr58516.C: New test.

--- gcc/cp/semantics.c.mp       2013-09-24 17:24:59.907548551 +0200
+++ gcc/cp/semantics.c  2013-09-24 17:25:04.251564960 +0200
@@ -5199,7 +5199,9 @@ finish_transaction_stmt (tree stmt, tree
     {
       tree body = build_must_not_throw_expr (TRANSACTION_EXPR_BODY (stmt),
                                             noex);
-      SET_EXPR_LOCATION (body, EXPR_LOCATION (TRANSACTION_EXPR_BODY (stmt)));
+      /* This may occur when the STATEMENT_LIST is empty.  */
+      if (CAN_HAVE_LOCATION_P (body))
+        SET_EXPR_LOCATION (body, EXPR_LOCATION (TRANSACTION_EXPR_BODY (stmt)));
       TREE_SIDE_EFFECTS (body) = 1;
       TRANSACTION_EXPR_BODY (stmt) = body;
     }
--- gcc/testsuite/g++.dg/tm/pr58516.C.mp        2013-09-24 17:27:08.859055542 
+0200
+++ gcc/testsuite/g++.dg/tm/pr58516.C   2013-09-24 17:28:29.829354635 +0200
@@ -0,0 +1,7 @@
+// { dg-do compile }
+// { dg-options "-std=c++0x -fgnu-tm" }
+
+void foo()
+{
+  __transaction_atomic noexcept(false) {}
+}

        Marek