From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id 388E73858CDB; Wed, 24 May 2023 20:28:08 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 388E73858CDB
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1684960088;
	bh=rT46kSHp7YD0PFywQYoLCNsVvKrGm9HkX92xlekN0+4=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=wWUoEbICiEwc7Y8CWxOn8pgLhUtRO0RTZzOOxmBccYhVOwizmVFOp1lJrPzVAj8/t
	 6M+YX2bZ5wrpp0OLx4AaO/bnvCSnLweTU8NGndbRhc8v2e+ueP4wTYHxF+GVIOvQ8t
	 Dw8KbDftys/e6AMrspvpUFrK2nUSXGaW9LTminqM=
From: "jason at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/109876] [10/11/12/13/14 Regression] initializer_list not
 usable in constant expressions in a template
Date: Wed, 24 May 2023 20:28:07 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 12.0
X-Bugzilla-Keywords: rejects-valid
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jason at gcc dot gnu.org
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P2
X-Bugzilla-Assigned-To: mpolacek at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 10.5
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-109876-4-Z36thFpScU@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-109876-4@http.gcc.gnu.org/bugzilla/>
References: <bug-109876-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109876

--- Comment #9 from Jason Merrill <jason at gcc dot gnu.org> ---
(In reply to Marek Polacek from comment #8)
> > Instead, we should probably treat num as value-dependent even though it=
 actually isn't.
>=20
> An attempt to implement that:
>=20
> --- a/gcc/cp/pt.cc
> +++ b/gcc/cp/pt.cc
> @@ -27969,6 +27969,12 @@ value_dependent_expression_p (tree expression)
>        else if (TYPE_REF_P (TREE_TYPE (expression)))
>     /* FIXME cp_finish_decl doesn't fold reference initializers.  */
>     return true;
> +      else if (DECL_DECLARED_CONSTEXPR_P (expression)
> +          && TREE_STATIC (expression)

I'd expect we could get a similar issue with non-static constexprs.

> +          && !DECL_NAMESPACE_SCOPE_P (expression)

This seems an unnecessary optimization?

> +          && DECL_INITIAL (expression)

Perhaps we also want to return true if DECL_INITIAL is null?

> +          && TREE_CODE (DECL_INITIAL (expression)) =3D=3D IMPLICIT_CONV_=
EXPR)

Maybe !TREE_CONSTANT?=