http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55541
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jason at gcc dot gnu.org
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-11-30
13:03:40 UTC ---
I've tried to do:
--- gcc/cp/decl.c.jj 2012-11-19 14:41:16.000000000 +0100
+++ gcc/cp/decl.c 2012-11-30 12:24:42.255349700 +0100
@@ -13700,7 +13700,27 @@ finish_function (int flags)
{
/* Make it so that `main' always returns 0 by default. */
if (DECL_MAIN_P (current_function_decl))
- finish_return_stmt (integer_zero_node);
+ {
+ /* If there is so far just a single statement, BIND_EXPR
+ with the whole main function body in it, push
+ return 0 stmt at the end of its body instead of after
+ the BIND_EXPR, so that variables declared in the function
+ scope are still in scope on the return stmt. */
+ tree bind = NULL_TREE;
+ if (TREE_CODE (cur_stmt_list) == STATEMENT_LIST)
+ {
+ tree_stmt_iterator i = tsi_start (cur_stmt_list);
+ if (tsi_one_before_end_p (i)
+ && TREE_CODE (tsi_stmt (i)) == BIND_EXPR)
+ {
+ bind = tsi_stmt (i);
+ vec_safe_push (stmt_list_stack, BIND_EXPR_BODY (bind));
+ }
+ }
+ finish_return_stmt (integer_zero_node);
+ if (bind)
+ BIND_EXPR_BODY (bind) = stmt_list_stack->pop ();
+ }
if (use_eh_spec_block (current_function_decl))
finish_eh_spec_block (TYPE_RAISES_EXCEPTIONS
which makes sure that the return 0; has the right locus (for C99 similar change
would be needed), unfortunately it doesn't fix this.
Unlike C, the C++ FE creates an extra BLOCK around the BLOCK with BLOCK_VARS i
in this case, supposedly for the argument scope, so DECL_INITIAL
(current_function_decl) is in C the block with i var, but in C++ a block whose
BLOCK_SUBBLOCK is block with i var. While the return stmt with the above patch
still has correct block, it seems to be actually completely ignored in the end,
because what matters actually is epilogue_location (in 4.7 and earlier
epilogue_locator). cfgexpand.c and expand_function_end now set
epilogue_location to the input_location, when outside of particular stmt
expansion, which doesn't have a block, and I assume that DECL_INITIAL is then
used. So the question is, can the C++ FE (when?) get rid of the outermost
BLOCK and change DECL_INITIAL (perhaps during genericization or so) to the real
function body scope instead.
