Re: [BUG] ignored trap and subshell

[Peter Stephenson <p.w.stephenson@ntlworld.com>]

> On 25 August 2021 at 11:10 Peter Stephenson <p.w.stephenson@ntlworld.com> wrote:
> > On 24 August 2021 at 17:23 Vincent Lefevre <vincent@vinc17.net> wrote:
> > The zshmisc(1) man page says:
> > 
> >     ( list )
> >         Execute list in a subshell.  Traps set by the trap builtin are
> >         reset to their default values while executing list.
> > 
> > However, with "emulate sh", ignored traps should still be ignored
> > in the subshell according to POSIX, and zsh 5.8 fails do conform:
> 
> I think this is straightforward.  POSIXTRAPS is clearly the option for the job.

And some documentation; the place Vincent mentioned looks like the obvious one
(we have at least one piece of evidence it gets read...)

diff --git a/Doc/Zsh/grammar.yo b/Doc/Zsh/grammar.yo
index 2eb2018d2..f8f4ada86 100644
--- a/Doc/Zsh/grammar.yo
+++ b/Doc/Zsh/grammar.yo
@@ -288,7 +288,9 @@ for each selection until a break or end-of-file is encountered.
 cindex(subshell)
 item(tt(LPAR()) var(list) tt(RPAR()))(
 Execute var(list) in a subshell.  Traps set by the tt(trap) builtin
-are reset to their default values while executing var(list).
+are reset to their default values while executing var(list); an
+exception is that ignored signals will continue to be ignored
+if the option tt(POSIXTRAPS) is set.
 )
 item(tt({) var(list) tt(}))(
 Execute var(list).
diff --git a/Src/exec.c b/Src/exec.c
index 49ff88b80..79d8064b6 100644
--- a/Src/exec.c
+++ b/Src/exec.c
@@ -1033,7 +1033,8 @@ entersubsh(int flags, struct entersubsh_ret *retp)
 
     if (!(flags & ESUB_KEEPTRAP))
 	for (sig = 0; sig < SIGCOUNT; sig++)
-	    if (!(sigtrapped[sig] & ZSIG_FUNC))
+	    if (!(sigtrapped[sig] & ZSIG_FUNC) &&
+		!(isset(POSIXTRAPS) && (sigtrapped[sig] & ZSIG_IGNORED)))
 		unsettrap(sig);
     monitor = isset(MONITOR);
     job_control_ok = monitor && (flags & ESUB_JOB_CONTROL) && isset(POSIXJOBS);