Re: C++ PATCH to fix ICE with NSDMI and this pointer (PR c++/79796)

[Jason Merrill <jason at redhat dot com>]

OK.

On Fri, Mar 3, 2017 at 6:34 AM, Marek Polacek <polacek@redhat.com> wrote:
> We weren't replacing  PLACEHOLDER_EXPR in the following testcase, leading to a
> crash in the gimplifier.  The fix seems to be to use replace_placeholders, the
> question is where.  These three functions have it:
> cp_gimplify_init_expr
> store_init_value
> build_new_1
> But we call neither so I tried adding the call to build_over_call, right
> after we create the MODIFY_EXPR with the NSDMI, and that seemed to work
> out.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2017-03-03  Marek Polacek  <polacek@redhat.com>
>
>         PR c++/79796 - ICE with NSDMI and this pointer
>         * call.c (build_over_call): Handle NSDMI with a 'this' by calling
>         replace_placeholders.
>
>         * g++.dg/cpp0x/nsdmi13.C: New test.
>
> diff --git gcc/cp/call.c gcc/cp/call.c
> index dc629b96..b821224 100644
> --- gcc/cp/call.c
> +++ gcc/cp/call.c
> @@ -8047,6 +8047,9 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
>         {
>           arg = cp_build_indirect_ref (arg, RO_NULL, complain);
>           val = build2 (MODIFY_EXPR, TREE_TYPE (to), to, arg);
> +         if (cxx_dialect >= cxx14)
> +           /* Handle NSDMI that refer to the object being initialized.  */
> +           replace_placeholders (arg, to);
>         }
>        else
>         {
> diff --git gcc/testsuite/g++.dg/cpp0x/nsdmi13.C gcc/testsuite/g++.dg/cpp0x/nsdmi13.C
> index e69de29..2751da3 100644
> --- gcc/testsuite/g++.dg/cpp0x/nsdmi13.C
> +++ gcc/testsuite/g++.dg/cpp0x/nsdmi13.C
> @@ -0,0 +1,13 @@
> +// PR c++/79796
> +// { dg-do compile { target c++11 } }
> +
> +struct A
> +{
> +  A* p = this;
> +};
> +
> +void foo()
> +{
> +  A a;
> +  a = A({});
> +}
>
>         Marek