Variable assignment in subshell affects parent. about ksh HOT 4 CLOSED

This bug was originally reported in att#7. It is caused by the following section of code, which does not save the state of variables in a newer scope:

I have made a pull request (#16) to fix this bug.

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For the acronym-deficient: SSCCE. Take your pick, all of them might apply... ;)

Meanwhile, I've found that if we change the second function's form to that of a POSIX subshell function definition:

unset a b
c=0

function set_ac { a=1; c=1; }
set_abc() ( set_ac ; b=1 )

set_abc
echo "a=$a b=$b c=$c"

…the bug vanishes. Which suggests to me that it is probably a bug in the parser, and not so much in the subshell mechanism itself. It appears that the subshell in your original SSCCE is wrongly optimised out.

from ksh.

My suspicion that it was a parser issue looks to be wrong. If you change set_abc() back into a ksh-style function and defeat any possible optimisation by adding an extra command:

function set_abc { ( set_ac ; b=1 ); echo end; }

…then the bug still occurs.

from ksh.

Fixed by #16. Many thanks @JohnoKing!

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