On Wed, 21 Dec 2022, Patrick Palka wrote:
> Here during ahead of time checking of C{}, we indirectly call get_nsdmi
> for C::m from finish_compound_literal, which in turn calls
> break_out_target_exprs for C::m's (non-templated) initializer, during
> which we end up building a call to A::~A and checking expr_noexcept_p
> for it (from build_vec_delete_1). But this is all done with
> processing_template_decl set, so the built A::~A call is templated
> (whose form r12-6897-gdec8d0e5fa00ceb2 recently changed) which
> expr_noexcept_p doesn't expect and we crash.
>
> In r10-6183-g20afdcd3698275 we fixed a similar issue by guarding a
> expr_noexcept_p call with !processing_template_decl, which works here
> too. But it seems to me since the initializer we obtain in get_nsdmi is
> always non-templated, it should be calling break_out_target_exprs with
> processing_template_decl cleared since otherwise the function might end
> up mixing templated and non-templated trees.
>
> I'm not sure about this though, perhaps this is not the best fix here.
> Alternatively, when processing_template_decl we could make get_nsdmi
> avoid calling break_out_target_exprs at all or something. Additionally,
> perhaps break_out_target_exprs should be a no-op more generally when
> processing_template_decl since we shouldn't see any TARGET_EXPRs inside
> a template?
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu.
Note this is a 12 regression so I suppose there's also the question of
what's safest to backport vs what's the best fix..
>
> PR c++/108116
>
> gcc/cp/ChangeLog:
>
> * init.cc (get_nsdmi): Clear processing_template_decl before
> processing the non-templated initializer.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/cpp0x/nsdmi-template24.C: New test.
> ---
> gcc/cp/init.cc | 8 ++++++-
> gcc/testsuite/g++.dg/cpp0x/nsdmi-template24.C | 22 +++++++++++++++++++
> 2 files changed, 29 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/g++.dg/cpp0x/nsdmi-template24.C
>
> diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
> index 73e6547c076..c4345ebdaea 100644
> --- a/gcc/cp/init.cc
> +++ b/gcc/cp/init.cc
> @@ -561,7 +561,8 @@ perform_target_ctor (tree init)
> return init;
> }
>
> -/* Return the non-static data initializer for FIELD_DECL MEMBER. */
> +/* Return the non-static data initializer for FIELD_DECL MEMBER.
> + The initializer returned is always non-templated. */
>
> static GTY((cache)) decl_tree_cache_map *nsdmi_inst;
>
> @@ -670,6 +671,11 @@ get_nsdmi (tree member, bool in_ctor, tsubst_flags_t
> complain)
> current_class_ptr = build_address (current_class_ref);
> }
>
> + /* Since INIT is always non-templated clear processing_template_decl
> + before processing it so that we don't interleave templated and
> + non-templated trees. */
> + processing_template_decl_sentinel ptds;
> +
> /* Strip redundant TARGET_EXPR so we don't need to remap it, and
> so the aggregate init code below will see a CONSTRUCTOR. */
> bool simple_target = (init && SIMPLE_TARGET_EXPR_P (init));
> diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-template24.C
> b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template24.C
> new file mode 100644
> index 00000000000..202c67d7321
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template24.C
> @@ -0,0 +1,22 @@
> +// PR c++/108116
> +// { dg-do compile { target c++11 } }
> +
> +#include <initializer_list>
> +
> +struct A {
> + A(int);
> + ~A();
> +};
> +
> +struct B {
> + B(std::initializer_list<A>);
> +};
> +
> +struct C {
> + B m{0};
> +};
> +
> +template<class>
> +void f() {
> + C c = C{};
> +};
> --
> 2.39.0.95.g7c2ef319c5
>
>
