testBit should work with BackwardsIndex

[rotu]

Summary

testBit in std/bitops should be able to accept an index from the end of a type.

Description

To get the msb bit of an integer, you currently have to do something like:

testBit(x, BitsRange[typeof x].high) or testBit(x, sizeof(x)*8-1)

It would be nicer if this could be simply testBit(x, ^1)

Note that a naive implementation would be slightly less than ideal since, unlike range, BackwardsIndex is not bounds-checked at compile time. E.g. [0,1,2][5] fails at compile time but [0,1,2][^4] fails at runtime.

Alternatives

No response

Standard Output Examples

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Backwards Compatibility

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Links

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