[libc++] Why doesn't libc++ define std::vector<bool>::const_reference as bool?

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1

Hi. According to the C++ Standard (section [vector.bool]), std::vector::const_reference should be defined as bool. libc++ defines it as std::__1::__bit_const_reference<std::__1::vector<bool, std::__1::allocator>>]. Is this divergence from the standard intentional? If it is, what is the purpose?

2

Unless I’m mis-reading the spec, vector<bool>::const_reference is implementation defined. Not bool. See [vector.bool].

/Eric

3

Unless I'm mis-reading the spec, `vector<bool>::const_reference` is
implementation defined. Not bool. See [vector.bool]
<http://eel.is/c++draft/vector.bool&gt;\.

It says:

using const_reference = bool;

4

Looking again, it seems like a libc++ bug. Not sure if Howard intended to be non-conforming here, but it’s likely a mistake.

Feel free to file a bug.

/Eric

5

Actually Howard explains this non-conformance in a self answer Stackoverflow question "Why is libc++'s vector::const_reference not bool?”:

https://stackoverflow.com/q/31974237/1708801

Regards
Shafik