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Remove a buggy optimization for variables in subshells
This bug was originally reported by @lijog in att#7 and has been reported again in ksh93#15. KSH does not save the state of a variable if it is in a newer scope. This is because of an optimization in sh_assignok first introduced in ksh93t+ 2010-05-24. Here is the code change in that version: return(np); /* don't bother to save if in newer scope */ - if(!(rp=shp->st.real_fun) || !(dp=rp->sdict)) - dp = sp->var; - if(np->nvenv && !nv_isattr(np,NV_MINIMAL|NV_EXPORT) && shp->last_root) - dp = shp->last_root; - if((mp=nv_search((char*)np,dp,HASH_BUCKET))!=np) - { - if(mp || !np->nvfun || np->nvfun->subshell>=sh.subshell) - return(np); - } + if(sp->var!=shp->var_tree && shp->last_root==shp->var_tree) + return(np); if((ap=nv_arrayptr(np)) && (mp=nv_opensub(np))) { This change was originally made to replace a buggier optimization. However, the current optimization causes variables set in subshells to wrongly affect the environment outside of the subshell, as the variable does not get set back to its original value. This patch simply removes the buggy optimization to fix this problem. src/cmd/ksh93/sh/subshell.c: - Remove a buggy optimization that caused variables set in subshells to affect the environment outside of the subshell. src/cmd/ksh93/tests/subshell.sh: - Add a regression test for setting variables in subshells. This test has to be run in a here document because it always returns the expected result when run directly in the regression test script.
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