[C++ PATCH] Fix FIX_TRUNC_EXPR instantiation (PR c++/84942)

[Jason Merrill]

OK.

On Fri, Mar 23, 2018 at 10:18 AM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Thu, Mar 22, 2018 at 02:02:01PM -0400, Jason Merrill wrote:
>> He hadn't yet checked in the relevant change, "Disable
>> auto_is_implicit_function_template_parm_p while parsing attributes".
>> That should happen soon.
>>
>> > but with
>> > the following patch we don't ICE, because args is NULL and
>> > tsubst_copy starts with:
>> > 14945     if (t == NULL_TREE || t == error_mark_node || args == NULL_TREE)
>> > 14946       return t;
>> > So, do you still want the FIX_TRUNC_EXPR handling removed or fixed (as done
>> > in the first patch)?
>>
>> Hmm, let's make it gcc_unreachable then.
>
> So like this?  Passes make check-c++-all on current trunk, where the above
> patch from Alex is already in.
>
> 2018-03-23  Jakub Jelinek  <jakub@redhat.com>
>
>         PR c++/84942
>         * pt.c (tsubst_copy_and_build) <case FIX_TRUNC_EXPR>: Replace
>         cp_build_unary_op call with gcc_unreachable ().
>
>         * g++.dg/cpp1y/pr84942.C: New test.
>
> --- gcc/cp/pt.c.jj      2018-03-23 09:49:38.063519286 +0100
> +++ gcc/cp/pt.c 2018-03-23 09:51:24.232501064 +0100
> @@ -17514,8 +17514,7 @@ tsubst_copy_and_build (tree t,
>                                 complain|decltype_flag));
>
>      case FIX_TRUNC_EXPR:
> -      RETURN (cp_build_unary_op (FIX_TRUNC_EXPR, RECUR (TREE_OPERAND (t, 0)),
> -                                false, complain));
> +      gcc_unreachable ();
>
>      case ADDR_EXPR:
>        op1 = TREE_OPERAND (t, 0);
> --- gcc/testsuite/g++.dg/cpp1y/pr84942.C.jj     2018-03-23 09:50:16.320512716 +0100
> +++ gcc/testsuite/g++.dg/cpp1y/pr84942.C        2018-03-23 09:52:33.408489183 +0100
> @@ -0,0 +1,6 @@
> +// PR c++/84942
> +// { dg-do compile { target c++14 } }
> +// { dg-options "-w" }
> +
> +int a(__attribute__((b((int)__builtin_inf() * 1ULL / auto))));
> +// { dg-error "expected primary-expression before" "" { target *-*-* } .-1 }
>
>
>         Jakub