Re: C++ PATCH to fix ICE in generic lambda with user-defined conversion (PR c++/84125)

[Jason Merrill <jason at redhat dot com>]

OK.

On Thu, Feb 1, 2018 at 3:23 PM, Marek Polacek <polacek@redhat.com> wrote:
> On Thu, Feb 01, 2018 at 02:35:08PM -0500, Jason Merrill wrote:
>> On Tue, Jan 30, 2018 at 3:18 PM, Marek Polacek <polacek@redhat.com> wrote:
>> > This testcase breaks since r256550 because we end up trying to build_address of
>> > a CONSTRUCTOR, but that doesn't work because we hit
>> >   gcc_checking_assert (TREE_CODE (t) != CONSTRUCTOR);
>> >
>> > finish_static_assert gets {} as 'condition'.
>>
>> Well, it gets X{}.
>>
>> > In the testcase we have a
>> > user-defined conversion, so {} should be turned to false, via
>> > perform_implicit_conversion_flags -> ... -> build_user_type_conversion_1, but
>> > that crashes as explained above.
>> >
>> > This only happens while processing generic lambda because processing_template_decl is 1,
>> > so finish_compound_literal returns {} instead of a TARGET_EXPR.
>>
>> So I think we should disable the above assert if
>> processing_template_decl; the CONSTRUCTOR is actually fine here.
>
> Thanks.  So like this?
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2018-02-01  Marek Polacek  <polacek@redhat.com>
>
>         PR c++/84125
>         * typeck.c (build_address): Relax the assert when
>         processing_template_decl.
>
>         * g++.dg/cpp1y/lambda-generic-84125.C:New test.
>
> diff --git gcc/cp/typeck.c gcc/cp/typeck.c
> index 1102f677f15..83e76782998 100644
> --- gcc/cp/typeck.c
> +++ gcc/cp/typeck.c
> @@ -5735,7 +5735,8 @@ build_address (tree t)
>  {
>    if (error_operand_p (t) || !cxx_mark_addressable (t))
>      return error_mark_node;
> -  gcc_checking_assert (TREE_CODE (t) != CONSTRUCTOR);
> +  gcc_checking_assert (TREE_CODE (t) != CONSTRUCTOR
> +                      || processing_template_decl);
>    t = build_fold_addr_expr_loc (EXPR_LOCATION (t), t);
>    if (TREE_CODE (t) != ADDR_EXPR)
>      t = rvalue (t);
> diff --git gcc/testsuite/g++.dg/cpp1y/lambda-generic-84125.C gcc/testsuite/g++.dg/cpp1y/lambda-generic-84125.C
> index e69de29bb2d..8bf6a09652e 100644
> --- gcc/testsuite/g++.dg/cpp1y/lambda-generic-84125.C
> +++ gcc/testsuite/g++.dg/cpp1y/lambda-generic-84125.C
> @@ -0,0 +1,10 @@
> +// PR c++/84125
> +// { dg-do compile { target c++14 } }
> +
> +struct X { constexpr operator bool() const { return true; } };
> +
> +int main(){
> +    [](auto) {
> +        static_assert(X{}, "");
> +    };
> +}
>
>         Marek