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Date: Mon, 20 Feb 2023 12:18:36 +0100 (CET)
From: Marc Glisse <marc.glisse@inria.fr>
Reply-To: gcc-help@gcc.gnu.org
To: Gabriel Ravier <gabravier@gmail.com>
cc: Xi Ruoyao <xry111@xry111.site>, Jonathan Wakely <jwakely.gcc@gmail.com>, 
    Jonny Grant <jg@jguk.org>, gcc-help <gcc-help@gcc.gnu.org>
Subject: Re: std::string add nullptr attribute
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On Mon, 20 Feb 2023, Gabriel Ravier via Gcc-help wrote:

> This is the kind of thing that makes me wonder why there isn't some kind of 
> `__builtin_unreachable_do_not_optimize()` builtin that allows one to mark 
> places in code that should never be reached and should thus be warned about 
> if such a thing happens while at the same time never doing any optimization 
> on the basis of the presence of the call.

-fsanitize=unreachable -fsanitize=null and others prevent the kind of 
optimization you are worried about.

-- 
Marc Glisse