Re: unreliable value of LINENO variable

[Giacomo Comes]

On Mon, Dec 04, 2023 at 12:21:11PM -0500, Chet Ramey wrote:
> On 12/4/23 8:46 AM, Giacomo Comes wrote:
> > I use often the value of LINEO in order
> > to know where to look for issues in a script.
> > Recently I discovered a bug.
> >
> > Please consider the following 6 line script:
> > ------------------------------------------------
> > #!/bin/bash
> >
> > if ((1)); then
> >         ( : ) ; echo 1 $LINENO
> > fi
> > echo 2 $LINENO
> > ------------------------------------------------
> > if executed it should print:
> > 1 4
> > 2 6
> > And indeed that's the output if I run it on openSUSE Leap 15.5
> > (bash 4.4). However if I execute it on openSUSE tumbleweed
> > (bash 5.2) the  output is:
> > 1 4
> > 2 5
>
> I can't reproduce this. I get the correct (bash-4.4) results on bash-5.1
> and bash-5.2. There does seem to be a problem with bash-5.0, but it was
> corrected in bash-5.1, according to my results.
>
> This is the case for both of your example scripts.
>
The script I was using was more complicated.
I did simplify it and I tested the simpler version only with bash 5.0, assuming
it would fail with 5.1 and 5.2 too.
The following one fails with every 5.x version:
------------------------------------------------
#!/bin/bash

if ((1)); then
        ( : ) | : ; echo 1 $LINENO
fi
echo 2 $LINENO
------------------------------------------------
Need to add a pipe after the subshell command.