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Missing template declaration in [array.tuple] #2553

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mclow opened this issue Dec 3, 2018 · 7 comments
Closed

Missing template declaration in [array.tuple] #2553

mclow opened this issue Dec 3, 2018 · 7 comments

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@mclow
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mclow commented Dec 3, 2018

In [array.tuple] (in N4778 and 4788), we see:

template<class T, size_t N>
     struct tuple_size<array<T, N>> : integral_constant<size_t, N> { };

tuple_element<I, array<T, N>>::type

I'm thinking that the tuple_element bit should look more like this:

template<class T, size_t N>
     tuple_element<I, array<T, N>>::type
@jwakely
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jwakely commented Dec 3, 2018

It needs size_t I as well.

I think this style of presentation is intentional, not a mistake. That doesn't make it good though.

@jwakely
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jwakely commented Dec 3, 2018

See [pair.astuple] and [variant.helper] as well.

@tkoeppe
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tkoeppe commented Dec 3, 2018

Looks like this has been broken size the first commit.

@tkoeppe
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tkoeppe commented Dec 3, 2018

I think we should add the missing template head to all those cases (the variant-values variant_alternative and pair's and array's tuple_element.

@jensmaurer
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But what does it mean? tuple_element<I, array<T, N>>::type is not valid C++ either way, if type is in fact a typedef: You can't have out-of-line definitions of member typedefs.

@jensmaurer jensmaurer added the decision-required A decision of the editorial group (or the Project Editor) is required. label Dec 20, 2018
@JohelEGP
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#2476 and https://wg21.link/LWG3166 are related.

@JohelEGP JohelEGP mentioned this issue Mar 15, 2019
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@jensmaurer
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Duplicate of #2786.

@jensmaurer jensmaurer removed the decision-required A decision of the editorial group (or the Project Editor) is required. label Sep 10, 2019
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5 participants
@mclow @jwakely @tkoeppe @JohelEGP @jensmaurer