[PATCH] c++: Handle structured bindings like anon unions in initializers [PR108474]

[Jakub Jelinek]

On Sun, Jan 22, 2023 at 07:19:07PM -0500, Jason Merrill wrote:
> > I was just trying to be careful, because unfortunately this spot
> > doesn't mean it really is only expanded in static var DECL_INITIAL,
> > it can make it into dynamic initializers, and most of DECL_VALUE_EXPRs
> > appear only in runtime code, otherwise we'd have much more of these issues.
> 
> But it shouldn't be harmful anywhere, right?
> 
> > But if you think it is ok, I'll test tonight a version just with
> > if (!data->genericize && DECL_HAS_VALUE_EXPR_P (stmt)
> 
> OK with that change.
> 
> Though, actually, why not instead fix expand_expr_real_1 (and staticp) to
> look through DECL_VALUE_EXPR?

I'm afraid that is way too late.  GIMPLE optimizations don't try to
regimplify expressions they take from DECL_INITIAL of static vars, they
just unshare them and use them.  So, if this is to be done in the generic
code, it would need to be done by cgraph around the time when it gimplifies
function if there is any such point for variables.

	Jakub