Re: r150960 changed ltmain.sh and broke the build

[Paolo Bonzini <bonzini at gnu dot org>]

> >       Patterns should not include the separator (unless escaped), even
> >       as part of a character class.  In conformance with Posix, the Cray
> >       `sed' rejects `s/[^/]*$//': use `s,[^/]*$,,'.
> > [...]
> >       Portable `sed' regular expressions should use `\' only to escape
> >       characters in the string `$()*.0123456789[\^n{}'.
>
>
>    Ah, I didn't read those two conditions as applying simultaneously.  Since
> the second condition essentially says that you must only ever escape a special
> character to make it non-meaningful or a normal character to make it special,
> maybe the first condition say something a bit more like ...
>
> >    Patterns should not include the separator (not even escaped, unless
> >    you fancy having to use a semantically significant metacharacter for
> >    your separator), even as part of a ...

No.  The problem is exactly when you use a semantically significant 
metacharacter for your separator.

\*   => unportable, a\* may become either a* or a\*
\>   => unportable, a\> may become either a> or a\>
\$   => unportable, a\$ may become either a$ or a\$
\,   => unportable, part of \{a,b\}
\|   => unportable, a\|b may become either a|b or a\|b and the latter
        may be parsed as alternation
\/   => in theory unportable in practice it would be insane to introduce
        a special sequence \/
\@ \: etc. => in theory unportable, in practice they should be fine.

All of these are forbidden by the wording in Autoconf manual.

One could add / to the list in the second paragraph, and saying 
something like "only / should be used as a separator if you wish to 
escape it, to avoid inadvertent introduction or escaping of regular 
expression operators".

Or even better, it should be left as is.

Paolo