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[class.union]/3 note contradicts normative wording #1073

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zygoloid opened this issue Nov 19, 2016 · 2 comments
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[class.union]/3 note contradicts normative wording #1073

zygoloid opened this issue Nov 19, 2016 · 2 comments
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@jensmaurer

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@zygoloid
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See https://groups.google.com/a/isocpp.org/d/msg/std-discussion/4BWeZosWYiY/5LKz98-dBQAJ

We should weaken the note, for instance by changing "must" to "should typically" and "will" to "will usually".
jensmaurer added a commit to jensmaurer/draft that referenced this issue Nov 23, 2016
@jensmaurer
[class.union] Clarify in the note that a default member
b124e3d 
initializer may prevent a defaulted special member function
from being implicitly deleted.

Fixes cplusplus#1073.
@jensmaurer jensmaurer mentioned this issue Nov 23, 2016
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@jensmaurer jensmaurer self-assigned this Nov 23, 2016
@jabelloc
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@jensmaurer
In reference to your commit, I believe the added sentence "Absent default member initializers" is necessary only for the non-trivial default constructor. That is, the additional condition imposed by the alluded sentence should not affect the other two constructors, the assignment operators and the destructor, mentioned in [class.union]/3.

@jensmaurer
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@jabelloc: Right. However, I think the note is now correct post-my patch, although it's not completely describing the situation. But then, it's a note, not a normative statement. I don't think I should repeat all the complexity of the real rule in this note, which is just trying to say "you can have non-trivial data members in a union, but if you do, you need to do the legwork yourself".

zygoloid pushed a commit that referenced this issue Nov 28, 2016
@jensmaurer @zygoloid
[class.union] Clarify in the note that a default member (#1113)
26a2e15 
initializer may prevent a defaulted special member function
from being implicitly deleted.

Fixes #1073.
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@zygoloid @jabelloc @jensmaurer