[minor] [[ "\\" =~ [^]"."] ]] returns false

[Stephane Chazelas]

That's a special case of the

[[ "\\" =~ ["."] ]]

returning true (because bash called regcomp("[\\.]") instead of
regcomp("[.]") I had reported some time ago and was then fixed.

Here. It's similar:

$ bash -c '[[ "\\" =~ [^]"."] ]]' || echo unexpected
unexpected

$ ltrace -e regcomp bash -c '[[ "\\" =~ [^]"."] ]]'
bash->regcomp(0x7ffc146e78c0, "[^]\\.]", 1)              = 0

I suspect bash thinks the first "]" closes the bracket
expression and thus assumes the "." is outside them so needs to
be escaped for the RE engine as it's quoted in the bash RE.

-- 
Stephane