Strange parameter visibility

Strange parameter visibility

[Kamil Jońca]

--8<---------------cut here---------------start------------->8---
%(x=1; x=2 echo | echo $x ; echo $x) 
1
1
--8<---------------cut here---------------end--------------->8---

but :
--8<---------------cut here---------------start------------->8---
%(x=1; x=2 | echo $x ; echo $x) 
2
2
--8<---------------cut here---------------end--------------->8---

What there are "2"-s in second example?
should'n "x=2" be treated as simple null command with its own
assignement?
KJ

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Re: Strange parameter visibility

[Eric Cook]

On 09/17/2016 02:11 PM, Kamil Jońca wrote:
> 
> --8<---------------cut here---------------start------------->8---
> %(x=1; x=2 echo | echo $x ; echo $x) 
> 1
> 1
> --8<---------------cut here---------------end--------------->8---
> 
> but :
> --8<---------------cut here---------------start------------->8---
> %(x=1; x=2 | echo $x ; echo $x) 
> 2
> 2
> --8<---------------cut here---------------end--------------->8---
> 
> What there are "2"-s in second example?
> should'n "x=2" be treated as simple null command with its own
> assignement?
> KJ
> 

It's a normal assignment just like the x=1. the weirdness is zsh
optimizing out a fork in the pipeline, so the scope of the
reassignment wasn't just a subshell.

Though, in the first example you put the variable into echo's
environment, the shell parameter x wasn't changed at all.

Re: Strange parameter visibility

[Bart Schaefer]

On Sat, Sep 17, 2016 at 6:42 PM, Eric Cook <llua@gmx.com> wrote:
>
> It's a normal assignment just like the x=1. the weirdness is zsh
> optimizing out a fork in the pipeline, so the scope of the
> reassignment wasn't just a subshell.

I have to conclude that's a bug -- it's OK to optimize out the fork,
but not to optimize out its side effects (or cause new ones).