Both the manual [1] and man page [2] state:
The words between the [[ and ]] do not undergo word splitting
and filename expansion. The shell performs tilde expansion,
parameter and variable expansion, arithmetic expansion,
command substitution, process substitution, and quote removal
on those words (the expansions that would occur if the words
were enclosed in double quotes).
However, the parenthetical is misleading because tilde expansion
and process substitution don't occur within double quotes. (I just
helped an IRC user who'd been confused by this text.)
[1]
https://git.savannah.gnu.org/cgit/bash.git/tree/doc/bashref.texi?h=devel&id=9c430f6bf37984e01977cc17f7066a6498aa4f18#n1153
[2]
https://git.savannah.gnu.org/cgit/bash.git/tree/doc/bash.1?h=devel&id=9c430f6bf37984e01977cc17f7066a6498aa4f18#n762
--
vq
