[Bug c++/19808] miss a warning about uninitialized members in constructor

["manu at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19808

--- Comment #23 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Jason Merrill from comment #22)
> It could be done specifically for uses in mem-initializers by walking the
> initializer in perform_mem_init to look for any references to members that
> haven't been marked yet.

Great! If I find some time in the following weeks, I will give it a try.

> A more general warning that would cover, say,
> 
> X x;
> x.x = x.y;
> 
> would need support in the existing back end -Wuninitialized code.

That is PR2972 and I think fixing this one is a prerequisite for fixing that
one. So let's go step by step.
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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/62056] Long compile times with large tuples
Date: Mon, 29 Sep 2014 14:43:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idb056

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
tr1::tuple doesn't support perfect-forwarding or move semantics

tr1::tuple doesn't support uses-allocator construction

tr1::tuple doesn't support 'final' classes

tr1::tuple doesn't have correct exception specifications

tr1::tuple doesn't prevent implicit conversions that would use explicit
constructors

tr1::tuple doesn't support tuple concatenation

If you can add all those features to the <tr1/tuple> implementation so that it
meets the C++11 requirements and it still compiles faster then I'd be
interested in your analysis of the remaining differences. Otherwise I'm going
to assume the difference is because the <tuple> header contains more than twice
as many lines of code and several additional features.