The concepts work ran into a bug whereby the TEMPLATE_PARM_DECL of a
TEMPLATE_TEMPLATE_PARM was missing its DECL_TEMPLATE_RESULT. Looking
into this more, I see that when instantiating a template template
parameter we end up with two TEMPLATE_DECLs: the main one and another in
the TEMPLATE_PARM_DECL. That's silly, they should be the same.
So this patch fixes reduce_template_parm_level to build up a proper
TEMPLATE_DECL, and changes tsubst_decl to use it.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit 4c2688271426e4f6e5cc0d93962efa3b1095b96b
Author: Jason Merrill <ja...@redhat.com>
Date: Sun Jul 5 23:21:34 2015 -0400
* pt.c (reduce_template_parm_level): Also build the TYPE_DECL
for a template template parameter.
(tsubst_decl) [TEMPLATE_DECL]: Use the TEMPLATE_DECL built
by reduce_template_parm_level.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 0302de1..3cd7bac 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -3740,9 +3740,14 @@ reduce_template_parm_level (tree index, tree type, int levels, tree args,
/* Template template parameters need this. */
if (TREE_CODE (decl) == TEMPLATE_DECL)
- DECL_TEMPLATE_PARMS (decl) = tsubst_template_parms
- (DECL_TEMPLATE_PARMS (TEMPLATE_PARM_DECL (index)),
- args, complain);
+ {
+ DECL_TEMPLATE_RESULT (decl)
+ = build_decl (DECL_SOURCE_LOCATION (decl),
+ TYPE_DECL, DECL_NAME (decl), type);
+ DECL_ARTIFICIAL (DECL_TEMPLATE_RESULT (decl)) = true;
+ DECL_TEMPLATE_PARMS (decl) = tsubst_template_parms
+ (DECL_TEMPLATE_PARMS (orig_decl), args, complain);
+ }
}
return TEMPLATE_PARM_DESCENDANTS (index);
@@ -10687,22 +10692,15 @@ tsubst_decl (tree t, tree args, tsubst_flags_t complain)
/* Template template parameter is treated here. */
tree new_type = tsubst (TREE_TYPE (t), args, complain, in_decl);
if (new_type == error_mark_node)
- RETURN (error_mark_node);
+ r = error_mark_node;
/* If we get a real template back, return it. This can happen in
the context of most_specialized_partial_spec. */
- if (TREE_CODE (new_type) == TEMPLATE_DECL)
- return new_type;
-
- r = copy_decl (t);
- DECL_CHAIN (r) = NULL_TREE;
- TREE_TYPE (r) = new_type;
- DECL_TEMPLATE_RESULT (r)
- = build_decl (DECL_SOURCE_LOCATION (decl),
- TYPE_DECL, DECL_NAME (decl), new_type);
- DECL_TEMPLATE_PARMS (r)
- = tsubst_template_parms (DECL_TEMPLATE_PARMS (t), args,
- complain);
- TYPE_NAME (new_type) = r;
+ else if (TREE_CODE (new_type) == TEMPLATE_DECL)
+ r = new_type;
+ else
+ /* The new TEMPLATE_DECL was built in
+ reduce_template_parm_level. */
+ r = TEMPLATE_TEMPLATE_PARM_TEMPLATE_DECL (new_type);
break;
}
