On Tue, 25 Jan 2022, Patrick Palka wrote:
> Here when attempting to use B's implicitly deleted default constructor,
> mark_used rightfully returns false, but for the wrong reason: it
> tries to instantiate the implicit noexcept specifier, which only
> silently fails because get_defaulted_eh_spec suppresses diagnostics
> for deleted functions. This causes us to ICE on the first testcase
> (thanks to the sanity check in finish_expr_stmt) and accept the second
> invalid testcase without complaint.
>
> To fix this, this patch makes mark_used avoid attempting to instantiate
> the noexcept specifier on a deleted function, so that mark_used will
> instead directly reject (and diagnose) such a function due to its
> deletedness.
>
> Bootstrap and regtested on x86_64-pc-linux-gnu, does this look OK for
> trunk?
... and perhaps release branches given that the second PR is a
regression relative to GCC 8?
>
> PR c++/101532
> PR c++/104225
>
> gcc/cp/ChangeLog:
>
> * decl2.cc (mark_used): Don't call with
> maybe_instantiate_noexcept on a deleted function.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/cpp0x/nsdmi-template21.C: New test.
> * g++.dg/cpp0x/nsdmi-template22.C: New test.
> ---
> gcc/cp/decl2.cc | 1 +
> gcc/testsuite/g++.dg/cpp0x/nsdmi-template21.C | 10 ++++++++++
> gcc/testsuite/g++.dg/cpp0x/nsdmi-template22.C | 12 ++++++++++++
> 3 files changed, 23 insertions(+)
> create mode 100644 gcc/testsuite/g++.dg/cpp0x/nsdmi-template21.C
> create mode 100644 gcc/testsuite/g++.dg/cpp0x/nsdmi-template22.C
>
> diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
> index 69b97449eac..b68cf96fa81 100644
> --- a/gcc/cp/decl2.cc
> +++ b/gcc/cp/decl2.cc
> @@ -5774,6 +5774,7 @@ mark_used (tree decl, tsubst_flags_t complain)
> used_types_insert (DECL_CONTEXT (decl));
>
> if (TREE_CODE (decl) == FUNCTION_DECL
> + && !DECL_DELETED_FN (decl)
> && !maybe_instantiate_noexcept (decl, complain))
> return false;
>
> diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-template21.C
> b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template21.C
> new file mode 100644
> index 00000000000..b9d4f4a4b9a
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template21.C
> @@ -0,0 +1,10 @@
> +// PR c++/101532
> +// { dg-do compile { target c++11 } }
> +
> +class A { ~A(); };
> +
> +template<class> class B { // { dg-error "private" }
> + A f = A();
> +};
> +
> +B<int> b; // { dg-error "deleted" }
> diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-template22.C
> b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template22.C
> new file mode 100644
> index 00000000000..bbcc7d9732e
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template22.C
> @@ -0,0 +1,12 @@
> +// PR c++/104225
> +// { dg-do compile { target c++11 } }
> +
> +class A { ~A(); };
> +
> +template<class> class B { // { dg-error "private" }
> + A f = A();
> +};
> +
> +int main() {
> + new B<int>; // { dg-error "deleted" }
> +}
> --
> 2.35.0
>
>
