bug#33255: 27.0.50; expand-file-name: default directory expanded twice if relative

[Glenn Morris]

Paul Eggert wrote:

> It needs to be read in context. Section 2.6.1 is about tilde expansion
> in the shell, e.g., how to treat commands like this:
>
> cd ~eggert/xxx
> cd ~/yyy
>
> 2.6.1 says "If the login name is null (that is, the tilde-prefix
> contains only the tilde), the tilde-prefix is replaced by the value of
> the variable /HOME."/ This is talking about the second "echo" example
> which uses a null login name, and it means that the second example is
> treated like this:
>
> cd "$HOME"/yyy/

This seems to be telling me what tilde expansion is.

I am at this point looking for any documentation (not even from POSIX,
any shell or frankly any Unix utility will do) that says "HOME need not
be absolute, if not, here's how that is handled". So far all I see from
POSIX is that it doesn't say anything about whether HOME is absolute or
not.