This patch fixes an ICE in a checking build where structural_comptypes
disagrees with TYPE_CANONICAL.
An (implicit) template alias has a different TYPE_TI_TEMPLATE to the
thing its aliasing. That make structural comparison think it's
different. In the testcase we end up thinking 'Loc' refers to a
different template than 'Traits<T>'
Solved by breaking TYPE_TEMPLATE_INFO into an underlying helper that
doesn't deal with type aliases. While there, I noticed
TYPE_TEMPLATE_INFO was doing more work than necessary because it checked
twice whether DECL_LANG_SPECIFIC (TYPE_NAME (NODE)) was non-null.
There's no need to check it again in the branch we can only get to when
it's non-null. I also removed some unnecessary parens.
ok?
nathan
--
Nathan Sidwell
2016-12-12 Nathan Sidwell <nat...@acm.org>
PR c++/78776
* cp-tree.h (TYPE_TEMPLATE_INFO_RAW): New, broken out of ...
(TYPE_TEMPLATE_INFO): ... here. Use it.
* typeck.c (structural_comptypes): Adjust record/union check to
avoid alias template confusion.
PR c++/78776
* g++.dg/cpp0x/pr78776.C: New.
Index: cp/cp-tree.h
===================================================================
--- cp/cp-tree.h (revision 243554)
+++ cp/cp-tree.h (working copy)
@@ -3038,22 +3038,25 @@ extern void decl_shadowed_for_var_insert
->template_info)
/* Template information for an ENUMERAL_, RECORD_, UNION_TYPE, or
- BOUND_TEMPLATE_TEMPLATE_PARM type. Note that if NODE is a
- specialization of an alias template, this accessor returns the
- template info for the alias template, not the one (if any) for the
- template of the underlying type. */
+ BOUND_TEMPLATE_TEMPLATE_PARM type. This ignores any alias
+ templateness of NODE. */
+
+#define TYPE_TEMPLATE_INFO_RAW(NODE) \
+ (TREE_CODE (NODE) == ENUMERAL_TYPE \
+ ? ENUM_TEMPLATE_INFO (NODE) \
+ : (TREE_CODE (NODE) == BOUND_TEMPLATE_TEMPLATE_PARM \
+ ? TEMPLATE_TEMPLATE_PARM_TEMPLATE_INFO (NODE) \
+ : (CLASS_TYPE_P (NODE) \
+ ? CLASSTYPE_TEMPLATE_INFO (NODE) \
+ : NULL_TREE)))
+
+/* If NODE is a specialization of an alias template, this accessor
+ returns the template info for the alias template. Otherwise behave
+ as TYPE_TEMPLATE_INFO_RAW. */
#define TYPE_TEMPLATE_INFO(NODE) \
- ((TYPE_ALIAS_P (NODE) && DECL_LANG_SPECIFIC (TYPE_NAME (NODE))) \
- ? (DECL_LANG_SPECIFIC (TYPE_NAME (NODE)) \
- ? DECL_TEMPLATE_INFO (TYPE_NAME (NODE)) \
- : NULL_TREE) \
- : ((TREE_CODE (NODE) == ENUMERAL_TYPE) \
- ? ENUM_TEMPLATE_INFO (NODE) \
- : ((TREE_CODE (NODE) == BOUND_TEMPLATE_TEMPLATE_PARM) \
- ? TEMPLATE_TEMPLATE_PARM_TEMPLATE_INFO (NODE) \
- : (CLASS_TYPE_P (NODE) \
- ? CLASSTYPE_TEMPLATE_INFO (NODE) \
- : NULL_TREE))))
+ (TYPE_ALIAS_P (NODE) && DECL_LANG_SPECIFIC (TYPE_NAME (NODE)) \
+ ? DECL_TEMPLATE_INFO (TYPE_NAME (NODE)) \
+ : TYPE_TEMPLATE_INFO_RAW (NODE))
/* Set the template information for an ENUMERAL_, RECORD_, or
Index: cp/typeck.c
===================================================================
--- cp/typeck.c (revision 243554)
+++ cp/typeck.c (working copy)
@@ -1284,18 +1284,23 @@ structural_comptypes (tree t1, tree t2,
case RECORD_TYPE:
case UNION_TYPE:
- if (TYPE_TEMPLATE_INFO (t1) && TYPE_TEMPLATE_INFO (t2)
- && (TYPE_TI_TEMPLATE (t1) == TYPE_TI_TEMPLATE (t2)
- || TREE_CODE (t1) == BOUND_TEMPLATE_TEMPLATE_PARM)
- && comp_template_args (TYPE_TI_ARGS (t1), TYPE_TI_ARGS (t2)))
- break;
+ {
+ /* Ignore any alias templateness. */
+ tree ti1 = TYPE_TEMPLATE_INFO_RAW (t1);
+ tree ti2 = TYPE_TEMPLATE_INFO_RAW (t2);
- if ((strict & COMPARE_BASE) && DERIVED_FROM_P (t1, t2))
- break;
- else if ((strict & COMPARE_DERIVED) && DERIVED_FROM_P (t2, t1))
- break;
+ if (ti1 && ti2
+ && (TI_TEMPLATE (ti1) == TI_TEMPLATE (ti2)
+ || TREE_CODE (t1) == BOUND_TEMPLATE_TEMPLATE_PARM)
+ && comp_template_args (TI_ARGS (ti1), TI_ARGS (ti2)))
+ break;
+ if ((strict & COMPARE_BASE) && DERIVED_FROM_P (t1, t2))
+ break;
+ else if ((strict & COMPARE_DERIVED) && DERIVED_FROM_P (t2, t1))
+ break;
- return false;
+ return false;
+ }
case OFFSET_TYPE:
if (!comptypes (TYPE_OFFSET_BASETYPE (t1), TYPE_OFFSET_BASETYPE (t2),
Index: testsuite/g++.dg/cpp0x/pr78776.C
===================================================================
--- testsuite/g++.dg/cpp0x/pr78776.C (revision 0)
+++ testsuite/g++.dg/cpp0x/pr78776.C (working copy)
@@ -0,0 +1,15 @@
+// PR c++/78776
+// { dg-do compile { target c++11 } }
+
+// ICE with canonical type verification
+
+template <typename> struct Traits;
+
+template <typename T>
+struct Bob {
+ using Loc = Traits<T>;
+ using typename Loc::Thing;
+
+ Thing Foo ();
+};
+
