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* [gcc r13-4799] c++: ICE with concepts TS multiple auto deduction [PR101886]
@ 2022-12-19 20:39 Patrick Palka
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From: Patrick Palka @ 2022-12-19 20:39 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:a7c8036b26082d8da001e05596777c5f911590e1
commit r13-4799-ga7c8036b26082d8da001e05596777c5f911590e1
Author: Patrick Palka <ppalka@redhat.com>
Date: Mon Dec 19 14:59:43 2022 -0500
c++: ICE with concepts TS multiple auto deduction [PR101886]
In extract_autos_r, we need to recompute TYPE_CANONICAL for the template
type parameter after adjusting its index, otherwise we end up with a
comptypes ICE for the below testcase. Note that such in-place type
adjustment isn't generally safe to do since the type could be the
TYPE_CANONICAL of another (unadjusted) type, but in this case the
canonical auto (of some level and 0 index) is the first auto (of that
level) that's created, and so any auto that we do end up adjusting can't
be the canonical one.
PR c++/101886
gcc/cp/ChangeLog:
* pt.cc (extract_autos_r): Recompute TYPE_CANONICAL after
adjusting the template type parameter's index. Simplify
by using TEMPLATE_TYPE_IDX. Add some sanity checks.
gcc/testsuite/ChangeLog:
* g++.dg/concepts/auto5.C: New test.
Diff:
---
gcc/cp/pt.cc | 12 +++++++++---
gcc/testsuite/g++.dg/concepts/auto5.C | 9 +++++++++
2 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 2516cca590e..2b7b3756b68 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -29243,18 +29243,24 @@ extract_autos_r (tree t, void *data)
{
/* All the autos were built with index 0; fix that up now. */
tree *p = hash.find_slot (t, INSERT);
- unsigned idx;
+ int idx;
if (*p)
/* If this is a repeated constrained-type-specifier, use the index we
chose before. */
- idx = TEMPLATE_PARM_IDX (TEMPLATE_TYPE_PARM_INDEX (*p));
+ idx = TEMPLATE_TYPE_IDX (*p);
else
{
/* Otherwise this is new, so use the current count. */
*p = t;
idx = hash.elements () - 1;
}
- TEMPLATE_PARM_IDX (TEMPLATE_TYPE_PARM_INDEX (t)) = idx;
+ if (idx != TEMPLATE_TYPE_IDX (t))
+ {
+ gcc_checking_assert (TEMPLATE_TYPE_IDX (t) == 0);
+ gcc_checking_assert (TYPE_CANONICAL (t) != t);
+ TEMPLATE_TYPE_IDX (t) = idx;
+ TYPE_CANONICAL (t) = canonical_type_parameter (t);
+ }
}
/* Always keep walking. */
diff --git a/gcc/testsuite/g++.dg/concepts/auto5.C b/gcc/testsuite/g++.dg/concepts/auto5.C
new file mode 100644
index 00000000000..f1d653efd87
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/auto5.C
@@ -0,0 +1,9 @@
+// PR c++/101886
+// { dg-do compile { target c++17_only } }
+// { dg-options "-fconcepts-ts" }
+
+template<typename...> struct A { };
+
+A<int, int> a;
+A<auto, auto> b1 = a;
+A<auto, auto> b2 = a;
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