Re: PATCH: test for trap EXIT fix.

[Peter Stephenson <pws@csr.com>]

Bart Schaefer wrote:
> On Oct 1,  1:01pm, Peter Stephenson wrote:
> }
> } The comment notes the following behaviour:
> } 
> } fn() { 
> }   ( trap 'print This is in the top-level function scope.' EXIT
> }     exit
> }   )
> } }
> 
> Wait ... why is that trap at the top-level function scope?  It's inside a
> subshell.  Shouldn't the subshell be its own scope?

That's never happened before.  We can introduce scopes for subshells, but
it's probably quite a lot of work.

> zsh% trap 'print PS1-level' EXIT; fn 			#1
> zsh% (trap 'print PS1-level' EXIT; fn)			#2
> zsh% trap 'print PS1-level' EXIT; (exit)		#3
> zsh% function TRAPEXIT { print PS1-level }; (exit)	#4
> PS1-level
> zsh% function TRAPEXIT { print PS1-level }; fn		#5
> zsh% 
> 
> What's the excuse for the PS1-level trap not running any case but #4?

The odd difference between #3 and #4 seems to be deliberate, weirdly
enough.  If you look at the top of entersubsh(), you will see traps are
usually cleared (cl == 2 implies this is not a `real' subshell, for some
definition of `not real' I haven't entirely worked out but which doesn't
apply in this case), but are left when the trap is a function:

    if (cl != 2)
	for (sig = 0; sig < VSIGCOUNT; sig++)
	    if (!(sigtrapped[sig] & ZSIG_FUNC))
		unsettrap(sig);

I can't imagine this is deliberately deliberate?  It must have been
deliberate in some accidental fashion.

I think the behaviour of clearing existing traps on entering subshells is
correct.  But we probably need to handle the case of traps inside the
subshell, when the subshell is in an arbitrary environment, better.
Maybe there's a simple tweak to the code I introduced so this can be done
without a full extra layer of scoping.

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 392070


**********************************************************************
The information transmitted is intended only for the person or
entity to which it is addressed and may contain confidential 
and/or privileged material. 
Any review, retransmission, dissemination or other use of, or
taking of any action in reliance upon, this information by 
persons or entities other than the intended recipient is 
prohibited.  
If you received this in error, please contact the sender and 
delete the material from any computer.
**********************************************************************