Parameter + prompt expansion %D{%T.%.} parser issue

Parameter + prompt expansion %D{%T.%.} parser issue

[Roland Eggner]

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emulate -R zsh -c 'print -l ${(%):-%D{%T.%.} %~} "${(%):-%D{%T.%.} %~}" ${(%):-"%D{%T.%.} %~"}'

Expected:
22:03:02.324 ~
22:03:02.324 ~
22:03:02.324 ~

Observed:
22:03:02.324 ~
22:03:02.324 %~}
22:03:02.324 ~


Note the trailing “%~}” in the 2nd line.

ZSH_PATCHLEVEL=zsh-5.2-282-ga22f4ea
uname -m -o
x86_64 GNU/Linux

Usage error?  Bug?  Feature?



-- 
Best regards
Roland Eggner

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Re: Parameter + prompt expansion %D{%T.%.} parser issue

[Mikael Magnusson]

On Mon, Jul 18, 2016 at 10:31 PM, Roland Eggner
<edvz2@systemanalysen.net> wrote:
> emulate -R zsh -c 'print -l ${(%):-%D{%T.%.} %~} "${(%):-%D{%T.%.} %~}" ${(%):-"%D{%T.%.} %~"}'
>
> Expected:
> 22:03:02.324 ~
> 22:03:02.324 ~
> 22:03:02.324 ~
>
> Observed:
> 22:03:02.324 ~
> 22:03:02.324 %~}
> 22:03:02.324 ~
>
>
> Note the trailing “%~}” in the 2nd line.
>
> ZSH_PATCHLEVEL=zsh-5.2-282-ga22f4ea
> uname -m -o
> x86_64 GNU/Linux
>
> Usage error?  Bug?  Feature?

Usage error, but it's kind of hard to understand what's going on there
admittedly. When ${} is unquoted, then the parser "knows" which {}
belong together, but when you have them under double quotes the {} for
the %D are not special in any way, so the terminating } for %D matches
the ${ as well. You need "${(%):-%D{%T.%.\} %~}" (It would also be a
good idea to use -r for print when testing quoting things although in
this case it makes no difference.)

The same thing happens when you use %F{} etc.

-- 
Mikael Magnusson

Re: Parameter + prompt expansion %D{%T.%.} parser issue

[Bart Schaefer]

On Jul 19,  2:21am, Mikael Magnusson wrote:
} Subject: Re: Parameter + prompt expansion %D{%T.%.} parser issue
}
} On Mon, Jul 18, 2016 at 10:31 PM, Roland Eggner
} <edvz2@systemanalysen.net> wrote:
} > emulate -R zsh -c 'print -l ${(%):-%D{%T.%.} %~} "${(%):-%D{%T.%.} %~}" ${(%):-"%D{%T.%.} %~"}'
} >
} > Observed:
} > 22:03:02.324 ~
} > 22:03:02.324 %~}
} > 22:03:02.324 ~
} >
} > Usage error?  Bug?  Feature?
} 
} Usage error, but it's kind of hard to understand what's going on there
} admittedly. When ${} is unquoted, then the parser "knows" which {}
} belong together

That's not quite right either.

You can get a better idea what's happening this way:

torch% setopt ignorebraces
torch% print -l ${(%):-%D{%T.%.} %~} "${(%):-%D{%T.%.} %~}" ${(%):-"%D{%T.%.} %~"}
20:33:34.148
%~}
20:33:34.148 %~}
20:33:34.148 ~

In the first (unquoted) case, with the default setopts (no_ignorebraces),
the substring {%T.%.} is parsed like a brace expansion, but then does not
expand because there are no commas.  So it's accidental that it works the
way expected.  With ignorebraces you see parameter expansion end at the
first close brace, leaving %~} to split into another argument to print.

The third form with the part after :- in quotes is really the only right
way, particularly given the space before %~.  Note that with parameter
expansions in all but the most antiquated versions of the shell you can
actually nest double quotes:

    print "${(%):-"%D{%T.%.} %~"}"