[BUG] one-shot variables aren't propagated past functions

[Denton Liu <liu.denton@xxxxxxxxx>]

Hi all,

I believe that I've encountered a bug in dash 0.5.10.2. With the
following input
	
	f () {
		echo $var
	}

	var=test f
	echo $var

I would expect the output to be
	
	test
	test

but the output is actually

	test
	<blank>

It seems like this violates the POSIX spec. Quoting Junio C Hamano[1]:
> Johannes Sixt <j.sixt@xxxxxxxxxxxxx> writes:
> 
> > Tarmigan Casebolt schrieb:
> >>         REQUEST_METHOD="GET" some_shell_function
> >
> >> I can't tell from my reading of the POSIX spec whether my usage was
> >> wrong or if dash is wrong,
> >
> > According to POSIX, variables set as shown above for shell functions are
> > not exported and retain their value after the function returns.
> 
> I actually looked for this yesterday, but didn't find a relevant
> definition.  But "2.9.5 Function Definition Command" [*1*] seems to
> address the issue: "When a function is executed, it shall have the
> syntax-error and variable-assignment properties described for special
> built-in utilities...".
> 
> And "2.14 Special Built-in Utilities" section [*2*] says "2. Variable
> assignments specified with special built-in utilities remain in effect
> after the built-in completes...".  Taking both together, it seems that
> the assignment should be in effect after the function returns.
> 
[...]
> 
> [References]
> 
> *1* http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_09_05
> *2* http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_14

It also seems like on bash 5.0.16, running with --posix produces the
expected output, although without --posix it produces the blank line.

Originally discussed here[2].

Thanks,

Denton

[1]: https://lore.kernel.org/git/7vljfzz0yd.fsf@xxxxxxxxxxxxxxxxxxxxxxxx/
[2]: https://lore.kernel.org/git/20200430092220.GA25331@generichostname/