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Date: Thu, 9 Dec 2021 21:41:40 +0100
From: Jan Hubicka <hubicka@kam.mff.cuni.cz>
To: Jakub Jelinek <jakub@redhat.com>
Cc: Jason Merrill <jason@redhat.com>, Jonathan Wakely <jwakely@redhat.com>,
 gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] c++, symtab: Support &typeid(x) == &typeid(y) in
 constant evaluation [PR103600]
Message-ID: <20211209204140.GA67389@kam.mff.cuni.cz>
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> 
> Ah, indeed, good idea.  FYI, clang++ seems to constant fold
> &typeid(x) != &typeid(y) already, so Jonathan could use it even for
> clang++ in the constexpr operator==.  But it folds even
> extern int &a, &b;
> constexpr bool c = &a != &b;
> regardless of whether some other TU has
> int a;
> int b __attribute__((alias (a));
> or not.
> 
> Here is an updated patch, ok for trunk if it passes bootstrap/regtest?

Looks good to me.  We are somewhat inconsistent on when we support
overleap and when we don't.  Also we produce local symbols that can be
later globalized by partitioning.  So perhaps we want this to eventually
become flag in symtab node and unify the logic in aliasing code etc, but
that can wait for next stage1.

Honza