Behavior of calling return from a trap

[dave reisner]

Hi all,

I'm noticing some odd behavior in an ERR trap with errtrace. It's
present in bash 3.2 and as well as 4.2. The simplest reproduction is
as follows:

--8<--
#!/bin/bash

somefunc() {
  false
  echo "shouldn't see this"
}

set -E
trap -- 'return 1' ERR

somefunc
echo "should see this"
--8<--

Both versions of bash throw an error, though fwiw the line number
differs: bash4 blames the line of where the trap is fired versus bash3
which blames the line where the trap is declared. The entire output of
the script is:

foo: line 4: return: can only `return' from a function or sourced
script
should see this

So, both versions give the intended behavior of returning from the
function despite the error. imo, there's a bug here somewhere, I'm
just not sure if it's the faulty error being thrown or if I shouldn't
be expecting the trap to work as it is when it's declared outside of a
function.

Regards,
Dave

Re: Behavior of calling return from a trap

[dave reisner]

On Tue, Apr 10, 2012 at 12:04:36PM -0400, Chet Ramey wrote:
> You're calling the error trap twice.  The first time you call it is after
> the `false' in the body of the function, and the `return' works as intended
> there.  Since you return 1, the call to `somefunc' fails, triggering the
> error trap again.  The second time you call it, you're not executing in a
> function context, and `return' throws an error.

Ah, of course. That makes a lot of sense. Thanks for clarifying.

dave