Re: [C++ PATCH]: Fix 16174

[Mark Mitchell <mark at codesourcery dot com>]

Nathan Sidwell wrote:

> Mark,
> this patch fixes 16174, a recent regression.  I think it's a known SFINAE
> failure that's newly exposed.
>
> I've propagated the tf_error flag through complete_type and
> instantiate_template_class.  I've also added a 'already tried this one'
> flag to avoid repeated instantiation attempts.
>
> I think this patch will make us SFINAE compliant up to the DR about
> whether complicated things like call exprs can be used inside sizeof
> inside a non-type template parm inside a return type instantiation 
> (phew).
>
> built and tested on 3.4 branch on i686-pc-linux-gnu, ok for there & HEAD?
> I've built it on HEAD, but the current state is such that I don't know
> what to expect of the testsuite.

I think this patch is OK, but I want to think about it a little bit.

I think we should leave complete_type (with its current parameters) 
around as a macro or forwarder function; that way the vast majority of 
callers will not have to be changed, and new uses will not have to add 
the extra parameter.  That would also make it easier for me to see the 
meat of the patch here.

Thanks,

--
Mark Mitchell
CodeSourcery, LLC
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mark@codesourcery.com