Re: [LTO PATCH RFA] PR c++/88049 - ICE with undefined destructor and anon namespace.

[Christophe Lyon <christophe dot lyon at linaro dot org>]

On Wed, 20 Feb 2019 at 02:58, Jason Merrill <jason@redhat.com> wrote:
>
> A type in an anonymous namespace can never be merged with one from
> another translation unit, so a member of such a type is always its own
> prevailing decl.
>
> I don't really understand the LTO concept of prevailing decl, or why we don't
> get here if the destructor is defined, but this seems reasonable and fixes the
> bug.
>
> Tested x86_64-pc-linux-gnu.  OK for trunk?
>
>         * lto-symtab.c (lto_symtab_prevailing_virtual_decl): Return early
>         for a type in an anonymous namespace.
> ---
>  gcc/lto/lto-symtab.c                 |  8 ++++++--
>  gcc/testsuite/g++.dg/lto/pr88049_0.C | 16 ++++++++++++++++
>  gcc/lto/ChangeLog                    |  6 ++++++
>  3 files changed, 28 insertions(+), 2 deletions(-)
>  create mode 100644 gcc/testsuite/g++.dg/lto/pr88049_0.C
>
> diff --git a/gcc/lto/lto-symtab.c b/gcc/lto/lto-symtab.c
> index 22da4c78b8c..343915c3cec 100644
> --- a/gcc/lto/lto-symtab.c
> +++ b/gcc/lto/lto-symtab.c
> @@ -1085,8 +1085,12 @@ lto_symtab_prevailing_virtual_decl (tree decl)
>  {
>    if (DECL_ABSTRACT_P (decl))
>      return decl;
> -  gcc_checking_assert (!type_in_anonymous_namespace_p (DECL_CONTEXT (decl))
> -                      && DECL_ASSEMBLER_NAME_SET_P (decl));
> +
> +  if (type_in_anonymous_namespace_p (DECL_CONTEXT (decl)))
> +    /* There can't be any other declarations.  */
> +    return decl;
> +
> +  gcc_checking_assert (DECL_ASSEMBLER_NAME_SET_P (decl));
>
>    symtab_node *n = symtab_node::get_for_asmname
>                      (DECL_ASSEMBLER_NAME (decl));
> diff --git a/gcc/testsuite/g++.dg/lto/pr88049_0.C b/gcc/testsuite/g++.dg/lto/pr88049_0.C
> new file mode 100644
> index 00000000000..7ac3618c2c8
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/lto/pr88049_0.C
> @@ -0,0 +1,16 @@
> +// PR c++/88049
> +// { dg-lto-do link }
> +// { dg-lto-options {{ -flto -O2 -w }} }
> +// { dg-extra-ld-options -r }
> +
> +template <typename> class a;
> +class b {};
> +template <typename e> a<e> d(char);
> +template <typename> class a : public b {
> +public:
> +  virtual ~a();
> +};
> +namespace {
> +  class f;
> +  b c = d<f>(int());
> +} // namespace


Hi Jason,

On bare-metal targets (arm, aarch64 using newlib), I'm using dejagnu's
testglue, which makes this new test fail because it also uses
g++_tg.o, leading to:
/arm-none-eabi/bin/ld: warning: incremental linking of LTO and non-LTO
objects; using -flinker-output=nolto-rel which will bypass whole
program optimization

Is there a way to avoid that (besides not using testglue) ?

Thanks,

Christophe

> diff --git a/gcc/lto/ChangeLog b/gcc/lto/ChangeLog
> index 6b183df3b0f..71a2a109e64 100644
> --- a/gcc/lto/ChangeLog
> +++ b/gcc/lto/ChangeLog
> @@ -1,3 +1,9 @@
> +2019-02-18  Jason Merrill  <jason@redhat.com>
> +
> +       PR c++/88049 - ICE with undefined destructor and anon namespace.
> +       * lto-symtab.c (lto_symtab_prevailing_virtual_decl): Return early
> +       for a type in an anonymous namespace.
> +
>  2019-01-09  Sandra Loosemore  <sandra@codesourcery.com>
>
>         PR other/16615
>
> base-commit: 79ae32275d4a19a1fc6ffebec9ac15a8c94b0b8f
> --
> 2.20.1
>