Tested x86_64-pc-linux-gnu, applying to trunk.
-- 8< --
In trying to reduce the testcase for PR125408, I came across an older
regression, dating back to r14-9938, though the problem wasn't in that
commit.
cp_walk_subtrees avoids walking into uses of typedefs because it wants to
look at what's actually written. But here we were also skipping over the
definition of the typedef, so extract_locals_r never got to see the use of
't', so later substitution failed.
Fixed by specifically handling typedef DECL_EXPR.
PR c++/125408
gcc/cp/ChangeLog:
* tree.cc (cp_walk_subtrees): Walk into the DECL_ORIGINAL_TYPE of a
typedef DECL_EXPR.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/lambda-targ33.C: New test.
---
gcc/cp/tree.cc | 4 ++++
gcc/testsuite/g++.dg/cpp2a/lambda-targ33.C | 24 ++++++++++++++++++++++
2 files changed, 28 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/lambda-targ33.C
diff --git a/gcc/cp/tree.cc b/gcc/cp/tree.cc
index c9b29900746..a99f5e19c0d 100644
--- a/gcc/cp/tree.cc
+++ b/gcc/cp/tree.cc
@@ -6407,6 +6407,10 @@ cp_walk_subtrees (tree *tp, int *walk_subtrees_p,
walk_tree_fn func,
WALK_SUBTREE (DECL_SIZE (decl));
WALK_SUBTREE (DECL_SIZE_UNIT (decl));
}
+ if (is_typedef_decl (TREE_OPERAND (t, 0)))
+ /* We avoid walking into typedefs above, but we do want to walk
+ into them if we're looking at the actual declaration. */
+ WALK_SUBTREE (DECL_ORIGINAL_TYPE (TREE_OPERAND (t, 0)));
break;
case LAMBDA_EXPR:
diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-targ33.C
b/gcc/testsuite/g++.dg/cpp2a/lambda-targ33.C
new file mode 100644
index 00000000000..3b42f322c77
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/lambda-targ33.C
@@ -0,0 +1,24 @@
+// PR c++/125408
+// { dg-do compile { target c++20 } }
+
+struct Role {
+ long id;
+};
+
+template <typename T> T Obj;
+template<int... I> struct A { };
+void sink(...);
+
+template <auto Ptr, typename Table>
+constexpr int find_member_index() {
+ constexpr auto& t = Obj<Table>;
+ []<int... Idx>(A<Idx...>) {
+ sink([]() {
+ using T1 = decltype(&(t.*Ptr));
+ return Idx;
+ }() ...);
+ }(A<1,2>{});
+ return 42;
+}
+
+auto i = find_member_index<&Role::id, Role>();
base-commit: e259a182e1f100a7693657cea20a207fd1323b82
--
2.54.0
