Re: Loops and pipes

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>
> Making it an error is quite simple:
>
> diff --git a/Src/exec.c b/Src/exec.c
> index 5f849db63..2e6684c96 100644
> --- a/Src/exec.c
> +++ b/Src/exec.c
> @@ -1258,6 +1258,7 @@ entersubsh(int flags, struct entersubsh_ret *retp)
>         clearjobtab(monitor);
>      get_usage();
>      forklevel = locallevel;
> +    loops = 0;
>  }
>
>  /* execute a string */
>

That works but for break/continue statements that are in a subshell of
their first enclosing loop it produces rather confusing error messages
stating that there are no loops. Here is a patch that avoids that:

- Forbid break/continue in subshells
<https://github.com/zsh-users/zsh/compare/master...paltherr:zsh:no-loop-control-from-subshell>

And here is a further patch that also checks that the break/continue
statements don't escape past the available loops:

- Forbid escaping past all enclosing loops in the same subshell
<https://github.com/paltherr/zsh/compare/forbid-escaping-past-all-loops-start...paltherr:zsh:forbid-escaping-past-all-loops>

The description of "continue n" states that it breaks out of n-1 loops and
resumes the nth loop but if there are m<n loops then it behaves as
"continue m", which is rather unexpected. The second patch avoids that by
making "continue n" (as well as "break n") illegal if n is greater than the
number of enclosing loops (started in the same subshell as the break/continue
statement).

Philippe

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<div dir=3D"ltr"><div class=3D"gmail_quote gmail_quote_container"><blockquo=
te class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px =
solid rgb(204,204,204);padding-left:1ex">Making it an error is quite simple=
:<br>
<br>
diff --git a/Src/exec.c b/Src/exec.c<br>
index 5f849db63..2e6684c96 100644<br>
--- a/Src/exec.c<br>
+++ b/Src/exec.c<br>
@@ -1258,6 +1258,7 @@ entersubsh(int flags, struct entersubsh_ret *retp)<br=
>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 clearjobtab(monitor);<br>
=C2=A0 =C2=A0 =C2=A0get_usage();<br>
=C2=A0 =C2=A0 =C2=A0forklevel =3D locallevel;<br>
+=C2=A0 =C2=A0 loops =3D 0;<br>
=C2=A0}<br>
<br>
=C2=A0/* execute a string */<br></blockquote><div><br></div><div>That works=
 but=C2=A0<span style=3D"background-color:transparent">for break/continue s=
tatements that are in a subshell of their first enclosing loop it produces=
=C2=A0</span><span style=3D"background-color:transparent">rather confusing =
error messages stating that there are no loops. Here is a patch that avoids=
 that:</span></div><div><span style=3D"background-color:transparent"><br></=
span></div><div>- <a href=3D"https://github.com/zsh-users/zsh/compare/maste=
r...paltherr:zsh:no-loop-control-from-subshell">Forbid break/continue in su=
bshells</a><span style=3D"background-color:transparent"></span></div><div><=
br></div><div>And here is a further patch that also checks that the=C2=A0<s=
pan style=3D"background-color:transparent">break/continue statements don&#3=
9;t escape past the available loops:</span></div><div><span style=3D"backgr=
ound-color:transparent"><br></span></div><div>- <a href=3D"https://github.c=
om/paltherr/zsh/compare/forbid-escaping-past-all-loops-start...paltherr:zsh=
:forbid-escaping-past-all-loops">Forbid escaping past all enclosing loops i=
n the same subshell</a><span style=3D"background-color:transparent"></span>=
</div><div><br></div><div>The description of &quot;continue n&quot; states =
that it breaks out of n-1 loops and resumes the nth loop but if there are m=
&lt;n loops then it behaves as &quot;continue m&quot;, which is rather unex=
pected. The second patch avoids that by making=C2=A0<span style=3D"backgrou=
nd-color:transparent">&quot;continue n&quot; (as well as &quot;break n&quot=
;) illegal if n is greater than the number of enclosing loops (started in t=
he same subshell as the=C2=A0</span>break/continue statement<span style=3D"=
background-color:transparent">).</span></div><div><br></div><div>Philippe</=
div><div><br></div></div></div>

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