The regression this commit fixes was first introduced in ksh93t
2008-07-25. It was previously worked around in 6f0e008c by forking
subshells if any special environment variable is unset.
The reason why this problem doesn't occur in ksh93s+ is because in
that version of ksh sh_assignok never moves nodes, it only clones
them. The second argument doesn't set NV_MOVE, which makes
`sh_assignok(np,0)` is similar to `sh_assignok(np,1)`. In ksh93t and
higher, setting the second argument to zero causes the node to be moved
with NV_MOVE, which causes the discipline function associated with
the variable node to be removed when `np->nvfun` is set to zero (i.e.
NULL). This is why a command like `(unset LC_NUMERIC; LC_NUMERIC=invalid)`
doesn't print a diagnostic, as it looses its discipline function.
This patch fixes the problem by cloning the node with sh_assignok
if it is a special variable with a discipline function. This allows
special variables to work as expected in virtual subshells. The
original workaround has been kept for the $PATH variable only, as
hash tables are still broken in virtual subshells. It has been updated
accordingly to only fork subshells if it detects the variable node
for PATH. I have added two more regression tests for changing the
PATH in subshells to make sure hash tables continue working as
expected with this fix.
src/cmd/ksh93/bltins/typeset.c:
- Only fork virtual subshells if the PATH will be changed. If a
variable is a special variable with a discipline function, it
should be just be cloned, not moved.
src/cmd/ksh93/sh/nvdisc.c:
- Add a comment to clarify that NV_MOVE will delete the discipline
function associated with the node.
src/cmd/ksh93/tests/subshells.sh:
- Add two more regression tests for unsetting the PATH in subshells,
one for if PATH is being pointed to by a nameref. Condense the
hash table tests by moving the main test into a single function.
7b994b6a7e