Re: Incorrect alias expansion within command substitution

[Chet Ramey]

On 2/3/22 4:20 PM, Robert Elz wrote:

>    | and it's just
>    | as clear that, let's say, implementations differ in this area.
>
> Aside from bash 5.2, not really.   There are lots of implementation bugs
> are limitations, but not really any expectation that the here doc end
> word text can be modified (beyond quote removal).

Wait, what are we talking about here? If we're talking about alias 
expansion inside here-document delimiters containing command substitutions,
the only thing common is the error. If we're talking about whether or not
the spaces are preserved in $( a b ), there are again several different
outputs.

>    | I'm comfortable with not supporting this use case.
>
> Fine, I doubt you'll ever encounter anything like that in the wild, but you
> are breaking backwards compat with bash up to 5.1 when you do that.

The first half of your sentence mitigates the issue in the second half. I
think it's more important to get the other posix conformance issue right.

>    | > cat <<$(cat</dev/null)
>    | > hello
>    | > $(cat</dev/null)
>    |
>    | It's not because the reconstituted text doesn't include redirections; the
>    | error message tells you that.
>
> No err message, bash (5.2-xxx) just sat there (at PS2) waiting for more
> input, until I SIGINT'd it.   I do most of these tests interactively, not
> in scripts, unless there is a real need (or they are very long).

Ah. I use the opposite approach. It usually produces more effective
results, especially if I need to start a debugger.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/