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From: "waffl3x at protonmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/110566] New: [13/14 Regression] ICE when instantiating
 function template with template template parameter with 2 or more auto
 parameters with a dependent member template, ICE in tsubst, at cp/pt.cc:16135
Date: Wed, 05 Jul 2023 21:52:07 +0000
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X-Bugzilla-Version: 13.1.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110566

            Bug ID: 110566
           Summary: [13/14 Regression] ICE when instantiating function
                    template with template template parameter with 2 or
                    more auto parameters with a dependent member template,
                    ICE in tsubst, at cp/pt.cc:16135
           Product: gcc
           Version: 13.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: waffl3x at protonmail dot com
  Target Milestone: ---

https://godbolt.org/z/6d4ec5va3

template<template<auto, auto> typename> void takes_templ();

template<typename>
struct v_v_member_templ_fn {
    template<auto, auto>
    using fn =3D void;
};

using ice =3D decltype(takes_templ<v_v_member_templ_fn<void>::template fn>(=
));

This one seems kind of boring to me, only interesting things to note are the
ICE only manifests with 2 or more (I assume) auto template parameters, it w=
orks
as expected with only a single auto template parameter.
The version of GCC on my local machine that exhibits this behavior is: 13.1=
.1
20230429

Not as convoluted as I'm used to, but at least that means it should be easy=
 to
fix! One can hope anyway.=