tree-iterator: C++11 range-for and tree_stmt_iterator

Like my recent patch to add ovl_range and lkp_range in the C++ front end,
this patch adds the tsi_range adaptor for using C++11 range-based 'for' with
a STATEMENT_LIST, e.g.

  for (tree stmt : tsi_range (stmt_list)) { ... }

This also involves adding some operators to tree_stmt_iterator that are
needed for range-for iterators, and should also be useful in code that uses
the iterators directly.

The patch updates the suitable loops in the C++ front end, but does not
touch any loops elsewhere in the compiler.

gcc/ChangeLog:

	* tree-iterator.h (struct tree_stmt_iterator): Add operator++,
	operator--, operator*, operator==, and operator!=.
	(class tsi_range): New.

gcc/cp/ChangeLog:

	* constexpr.c (build_data_member_initialization): Use tsi_range.
	(build_constexpr_constructor_member_initializers): Likewise.
	(constexpr_fn_retval, cxx_eval_statement_list): Likewise.
	(potential_constant_expression_1): Likewise.
	* coroutines.cc (await_statement_expander): Likewise.
	(await_statement_walker): Likewise.
	* module.cc (trees_out::core_vals): Likewise.
	* pt.c (tsubst_expr): Likewise.
	* semantics.c (set_cleanup_locs): Likewise.

1 files changed, 2 insertions, 3 deletions

diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index fe370a2..e40462d 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -613,9 +613,8 @@ set_cleanup_locs (tree stmts, location_t loc)
       set_cleanup_locs (CLEANUP_BODY (stmts), loc);
     }
   else if (TREE_CODE (stmts) == STATEMENT_LIST)
-    for (tree_stmt_iterator i = tsi_start (stmts);
-	 !tsi_end_p (i); tsi_next (&i))
-      set_cleanup_locs (tsi_stmt (i), loc);
+    for (tree stmt : tsi_range (stmts))
+      set_cleanup_locs (stmt, loc);
 }
 
 /* Finish a scope.  */