History expansion surprisingly sets event designator

History expansion surprisingly sets event designator

[Leah Neukirchen]

Hi,

on #zsh we discovered:

zsh 5.3.1 (x86_64-unknown-linux-gnu)
zsh-5.3.1-0-g06b1b7a    (and zsh-5.3.1-204-g62c4169, via danielsh)
% zsh -f
juno% printf a b c
a%
juno% echo x y z
x y z
juno% echo !printf:2<TAB><DEL>!:3<RET>
c

The first tab expansion will correctly expand to "b", but it changes
the event designator to the printf-line, resulting in !:3 expanding to "c",
while the typed in line "echo !:3" itself would refer to the previous
line, the echo-line, and should result in "z".
(Same for tab-expanding the second history reference.)

Pressing ^U will not reset this, but pressing ^C will.

thx,
-- 
Leah Neukirchen  <leah@vuxu.org>  http://leah.zone

Re: History expansion surprisingly sets event designator

[Peter Stephenson]

On Tue, 6 Jun 2017 17:50:03 +0200
Leah Neukirchen <leah@vuxu.org> wrote:
> Hi,
> 
> on #zsh we discovered:
> 
> zsh 5.3.1 (x86_64-unknown-linux-gnu)
> zsh-5.3.1-0-g06b1b7a    (and zsh-5.3.1-204-g62c4169, via danielsh)
> % zsh -f
> juno% printf a b c
> a%
> juno% echo x y z
> x y z
> juno% echo !printf:2<TAB><DEL>!:3<RET>
> c
>
> The first tab expansion will correctly expand to "b", but it changes
> the event designator to the printf-line, resulting in !:3 expanding to "c",
> while the typed in line "echo !:3" itself would refer to the previous
> line, the echo-line, and should result in "z".
> (Same for tab-expanding the second history reference.)
> 
> Pressing ^U will not reset this, but pressing ^C will.

Yes, that's how it works.  I haven't understood why you think it's a
problem but I presume you're used to some other shell.

If you want to turn this feature off, use CSH_JUNKIE_HISTORY; see the
HISTORY EXPANSION section in the zshexpn manual.  Or use two !!s to
refer to the immediately preceding event.

       By  default, a history reference with no event designator refers to the
       same event as any preceding history reference on that command line;  if
       it  is the only history reference in a command, it refers to the previ‐
       ous command.  However, if the option CSH_JUNKIE_HISTORY  is  set,  then
       every  history  reference  with no event specification always refers to
       the previous command.

pws

Re: History expansion surprisingly sets event designator

[Leah Neukirchen]

Peter Stephenson <p.stephenson@samsung.com> writes:

> On Tue, 6 Jun 2017 17:50:03 +0200
> Leah Neukirchen <leah@vuxu.org> wrote:
>
>> Hi,
>> 
>> on #zsh we discovered:
>> 
>> zsh 5.3.1 (x86_64-unknown-linux-gnu)
>> zsh-5.3.1-0-g06b1b7a    (and zsh-5.3.1-204-g62c4169, via danielsh)
>> % zsh -f
>> juno% printf a b c
>> a%
>> juno% echo x y z
>> x y z
>> juno% echo !printf:2<TAB><DEL>!:3<RET>
>> c
>>
>> The first tab expansion will correctly expand to "b", but it changes
>> the event designator to the printf-line, resulting in !:3 expanding to "c",
>> while the typed in line "echo !:3" itself would refer to the previous
>> line, the echo-line, and should result in "z".
>> (Same for tab-expanding the second history reference.)
>> 
>> Pressing ^U will not reset this, but pressing ^C will.
>
> Yes, that's how it works.  I haven't understood why you think it's a
> problem but I presume you're used to some other shell.

If my command line is "echo !:3" before pressing RET, it should always
print z, even if I fiddled around with tab expansion during editing.
I think this is quite confusing as-is.

-- 
Leah Neukirchen  <leah@vuxu.org>  http://leah.zone

Re: History expansion surprisingly sets event designator

[Peter Stephenson]

On Tue, 6 Jun 2017 18:54:57 +0200
Leah Neukirchen <leah@vuxu.org> wrote:
> If my command line is "echo !:3" before pressing RET, it should always
> print z, even if I fiddled around with tab expansion during editing.

I see what you mean.  It's not obvious the default event propagates
from the line editor to the history line substitution performed
on input.

We can restrict the scope easily enough.

pws

diff --git a/Src/hist.c b/Src/hist.c
index 350688d..da5a8b2 100644
--- a/Src/hist.c
+++ b/Src/hist.c
@@ -253,6 +253,7 @@ hist_context_save(struct hist_stack *hs, int toplevel)
     hs->hwend = hwend;
     hs->addtoline = addtoline;
     hs->hlinesz = hlinesz;
+    hs->defev = defev;
     /*
      * We save and restore the command stack with history
      * as it's visible to the user interactively, so if
@@ -296,6 +297,7 @@ hist_context_restore(const struct hist_stack *hs, int toplevel)
     hwend = hs->hwend;
     addtoline = hs->addtoline;
     hlinesz = hs->hlinesz;
+    defev = hs->defev;
     if (cmdstack)
 	zfree(cmdstack, CMDSTACKSZ);
     cmdstack = hs->cstack;
diff --git a/Src/zsh.h b/Src/zsh.h
index 22f73f8..137b2a5 100644
--- a/Src/zsh.h
+++ b/Src/zsh.h
@@ -2918,6 +2918,7 @@ struct hist_stack {
     int histdone;
     int stophist;
     int hlinesz;
+    zlong defev;
     char *hline;
     char *hptr;
     short *chwords;

Re: History expansion surprisingly sets event designator

[Leah Neukirchen]

Peter Stephenson <p.stephenson@samsung.com> writes:

> On Tue, 6 Jun 2017 18:54:57 +0200
> Leah Neukirchen <leah@vuxu.org> wrote:
>> If my command line is "echo !:3" before pressing RET, it should always
>> print z, even if I fiddled around with tab expansion during editing.
>
> I see what you mean.  It's not obvious the default event propagates
> from the line editor to the history line substitution performed
> on input.
>
> We can restrict the scope easily enough.

This seems to work as I expected it, thank you!

-- 
Leah Neukirchen  <leah@vuxu.org>  http://leah.zone