https://gcc.gnu.org/g:ed6ffc4e62f716d1b31d599d22594dd969da137f
commit r15-1621-ged6ffc4e62f716d1b31d599d22594dd969da137f Author: Marek Polacek <pola...@redhat.com> Date: Fri Jun 14 17:50:29 2024 -0400 c++: ICE with generic lambda and pack expansion [PR115425] In r13-272 we hardened the *_PACK_EXPANSION and *_ARGUMENT_PACK macros. That trips up here because make_pack_expansion returns error_mark_node and we access that with PACK_EXPANSION_LOCAL_P. PR c++/115425 gcc/cp/ChangeLog: * pt.cc (tsubst_pack_expansion): Return error_mark_node if make_pack_expansion doesn't work out. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/lambda-generic12.C: New test. Diff: --- gcc/cp/pt.cc | 2 ++ gcc/testsuite/g++.dg/cpp2a/lambda-generic12.C | 25 +++++++++++++++++++++++++ 2 files changed, 27 insertions(+) diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index daa8ac386dc..017cc7fd0ab 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -13775,6 +13775,8 @@ tsubst_pack_expansion (tree t, tree args, tsubst_flags_t complain, else result = tsubst (pattern, args, complain, in_decl); result = make_pack_expansion (result, complain); + if (result == error_mark_node) + return error_mark_node; PACK_EXPANSION_LOCAL_P (result) = PACK_EXPANSION_LOCAL_P (t); PACK_EXPANSION_SIZEOF_P (result) = PACK_EXPANSION_SIZEOF_P (t); if (PACK_EXPANSION_AUTO_P (t)) diff --git a/gcc/testsuite/g++.dg/cpp2a/lambda-generic12.C b/gcc/testsuite/g++.dg/cpp2a/lambda-generic12.C new file mode 100644 index 00000000000..219529c7c32 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/lambda-generic12.C @@ -0,0 +1,25 @@ +// PR c++/115425 +// { dg-do compile { target c++20 } } + +using size_t = decltype(sizeof(0)); + +template <int... I> +struct X {}; + +template<int... Is> +void foo(X<Is...>); + +template<auto> +struct S; + +template<class T> +auto test() { + constexpr static auto x = foo<X<__integer_pack (0)...>>(); // { dg-error "no matching function" } + return []<size_t... Is>(X<Is...>) { + (typename S<x[Is]>::type{}, ...); + }(X<__integer_pack (0)...>{}); +} + +int main() { + test<int>(); +}