When working on 94827 I noticed that process_template_parm was doing
more work than necessary -- using 'last_node' and later 'chainon'. This
fixes that up to just walk the list once.
Also, I didn't understand the reason why end_template_parms does a pop
of the dummy header, and then a push of the real one -- why not just
modify the dummy in place? Added a comment about that.
pushed to trunk.
nathan
--
Nathan Sidwell
2020-05-04 Nathan Sidwell <nat...@acm.org>
pt.c (process_template_parm): Don't walk the template list twice,
remember the final node instead.
(end_template_parm_list): Refactor. Comment on why we do a pop
and a push.
diff --git i/gcc/cp/pt.c w/gcc/cp/pt.c
index 8106c25a2d9..61cb75bf801 100644
--- i/gcc/cp/pt.c
+++ w/gcc/cp/pt.c
@@ -4496,29 +4496,27 @@ tree
process_template_parm (tree list, location_t parm_loc, tree parm,
bool is_non_type, bool is_parameter_pack)
{
- tree decl = 0;
- int idx = 0;
-
gcc_assert (TREE_CODE (parm) == TREE_LIST);
- tree defval = TREE_PURPOSE (parm);
- tree constr = TREE_TYPE (parm);
+ tree prev = NULL_TREE;
+ int idx = 0;
if (list)
{
- tree p = tree_last (list);
+ prev = tree_last (list);
- if (p && TREE_VALUE (p) != error_mark_node)
- {
- p = TREE_VALUE (p);
- if (TREE_CODE (p) == TYPE_DECL || TREE_CODE (p) == TEMPLATE_DECL)
- idx = TEMPLATE_TYPE_IDX (TREE_TYPE (p));
- else
- idx = TEMPLATE_PARM_IDX (DECL_INITIAL (p));
- }
+ tree p = TREE_VALUE (prev);
+ if (TREE_CODE (p) == TYPE_DECL || TREE_CODE (p) == TEMPLATE_DECL)
+ idx = TEMPLATE_TYPE_IDX (TREE_TYPE (p));
+ else if (TREE_CODE (p) == PARM_DECL)
+ idx = TEMPLATE_PARM_IDX (DECL_INITIAL (p));
++idx;
}
+ tree decl = NULL_TREE;
+ tree defval = TREE_PURPOSE (parm);
+ tree constr = TREE_TYPE (parm);
+
if (is_non_type)
{
parm = TREE_VALUE (parm);
@@ -4616,7 +4614,12 @@ process_template_parm (tree list, location_t parm_loc, tree parm,
parm = build_tree_list (defval, parm);
TEMPLATE_PARM_CONSTRAINTS (parm) = reqs;
- return chainon (list, parm);
+ if (prev)
+ TREE_CHAIN (prev) = parm;
+ else
+ list = parm;
+
+ return list;
}
/* The end of a template parameter list has been reached. Process the
@@ -4627,22 +4630,24 @@ process_template_parm (tree list, location_t parm_loc, tree parm,
tree
end_template_parm_list (tree parms)
{
- int nparms;
- tree parm, next;
tree saved_parmlist = make_tree_vec (list_length (parms));
- /* Pop the dummy parameter level and add the real one. */
+ /* Pop the dummy parameter level and add the real one. We do not
+ morph the dummy parameter in place, as it might have been
+ captured by a (nested) template-template-parm. */
current_template_parms = TREE_CHAIN (current_template_parms);
current_template_parms
= tree_cons (size_int (processing_template_decl),
saved_parmlist, current_template_parms);
- for (parm = parms, nparms = 0; parm; parm = next, nparms++)
+ for (unsigned ix = 0; parms; ix++)
{
- next = TREE_CHAIN (parm);
- TREE_VEC_ELT (saved_parmlist, nparms) = parm;
+ tree parm = parms;
+ parms = TREE_CHAIN (parms);
TREE_CHAIN (parm) = NULL_TREE;
+
+ TREE_VEC_ELT (saved_parmlist, ix) = parm;
}
--processing_template_parmlist;
