arithmetic + > + subshell might not be documented

[jidanni]

Might not be documented:

$ cat q
for i in : :; do :|: > x$((++a)); echo =$a=; done; ls x?; rm x?
for i in : :; do :   > x$((++b)); echo =$b=; done; ls x?; rm x?
$ bash q
==
==
x1
=1=
=2=
x1  x2