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Re: C++ PATCH for c++/87080, ICE with -Wpessimizing-move


OK.

On Sat, Aug 25, 2018 at 7:02 AM, Marek Polacek <polacek@redhat.com> wrote:
> The problem in this testcase was that we were calling is_std_move_p from
> template context, which breaks in cp_get_fndecl_from_callee.  This warning
> is not meant to warn while parsing a template, so I think we should apply this.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2018-08-24  Marek Polacek  <polacek@redhat.com>
>
>         PR c++/87080
>         * typeck.c (maybe_warn_pessimizing_move): Do nothing in a template.
>
>         * g++.dg/cpp0x/Wpessimizing-move5.C: New test.
>
> diff --git gcc/cp/typeck.c gcc/cp/typeck.c
> index 122d9dcd4b3..24647e29a55 100644
> --- gcc/cp/typeck.c
> +++ gcc/cp/typeck.c
> @@ -9192,6 +9192,11 @@ maybe_warn_pessimizing_move (tree retval, tree functype)
>    if (cxx_dialect < cxx11)
>      return;
>
> +  /* Wait until instantiation time, since we can't gauge if we should do
> +     the NRVO until then.  */
> +  if (processing_template_decl)
> +    return;
> +
>    /* This is only interesting for class types.  */
>    if (!CLASS_TYPE_P (functype))
>      return;
> diff --git gcc/testsuite/g++.dg/cpp0x/Wpessimizing-move5.C gcc/testsuite/g++.dg/cpp0x/Wpessimizing-move5.C
> index e69de29bb2d..02ad2113505 100644
> --- gcc/testsuite/g++.dg/cpp0x/Wpessimizing-move5.C
> +++ gcc/testsuite/g++.dg/cpp0x/Wpessimizing-move5.C
> @@ -0,0 +1,14 @@
> +// PR c++/87080
> +// { dg-do compile { target c++11 } }
> +// { dg-options "-Wpessimizing-move" }
> +
> +struct a {
> +  template<typename b> a &operator<<(b);
> +};
> +a c();
> +template<typename>
> +a fn2()
> +{
> +  int d = 42;
> +  return c() << d;
> +}


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