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https://bugs.gentoo.org/906310
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109850
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109241
https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=396a4e76afec30d2461638f569cae18955eb4ad2
From 396a4e76afec30d2461638f569cae18955eb4ad2 Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Wed, 22 Mar 2023 16:11:47 -0400
Subject: [PATCH] c++: local class in nested generic lambda [PR109241]
In this testcase, the tree walk to look for bare parameter packs was
confused by finding a type with no TREE_BINFO. But it should be fine that
it's unset; we already checked for unexpanded packs at parse time.
I also tried doing the partial instantiation of the local class, which is
probably the long-term direction we want to go, but for stage 4 let's go
with this safer change.
PR c++/109241
gcc/cp/ChangeLog:
* pt.cc (find_parameter_packs_r): Handle null TREE_BINFO.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/lambda-generic-local-class2.C: New test.
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -4106,10 +4106,14 @@ find_parameter_packs_r (tree *tp, int *walk_subtrees, void* data)
case TAG_DEFN:
t = TREE_TYPE (t);
if (CLASS_TYPE_P (t))
- /* Local class, need to look through the whole definition. */
- for (tree bb : BINFO_BASE_BINFOS (TYPE_BINFO (t)))
- cp_walk_tree (&BINFO_TYPE (bb), &find_parameter_packs_r,
- ppd, ppd->visited);
+ {
+ /* Local class, need to look through the whole definition.
+ TYPE_BINFO might be unset for a partial instantiation. */
+ if (TYPE_BINFO (t))
+ for (tree bb : BINFO_BASE_BINFOS (TYPE_BINFO (t)))
+ cp_walk_tree (&BINFO_TYPE (bb), &find_parameter_packs_r,
+ ppd, ppd->visited);
+ }
else
/* Enum, look at the values. */
for (tree l = TYPE_VALUES (t); l; l = TREE_CHAIN (l))
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-local-class2.C
@@ -0,0 +1,13 @@
+// PR c++/109241
+// { dg-do compile { target c++14 } }
+// { dg-options "" } no pedantic
+
+void g() {
+ [](auto) {
+ [](auto) {
+ ({
+ struct A {};
+ });
+ };
+ }(1);
+}
--
2.31.1
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