Re: [Bug-readline] vi-{cmd, ins}-mode-string and show-mode-in-prompt

[Rob Foehl]

On Thu, 7 Dec 2017, Chet Ramey wrote:

> On 12/6/17 11:46 PM, Rob Foehl wrote:
> > Any chance these could be made to work as documented, removing the
> > dependency on show-mode-in-prompt?
>
> The `dependency' on show-mode-in-prompt is intentional: the strings aren't
> prefixed to the displayed prompt string unless that variable is enabled.
> That has been the case even when the strings weren't user-settable (e.g.,
> bash-4.3). If the documentation doesn't make that clear, then I need to
> clarify it.

Right, but that's the issue here: in bash-4.3, for example, trying to use 
an inputrc which sets the various mode strings and show-mode-in-prompt 
just results in the prompt being mangled by the fixed strings included in 
that release, and the custom strings ignored.  Since there's no way to 
test the application version in readline conditionals, this means the 
inputrc isn't portable to older releases -- a problem with shared home 
directories and the like.

If, on the other hand, the mode string variables were used unconditionally 
after being set, and without show-mode-in-prompt set, then there is no 
issue with older releases -- and this is how they're currently documented 
to work in readline-7.0 / bash-4.4, even if that wasn't intentional.

This turned out to be a fairly minor change; see attached patch against 
current devel branch from git.  I believe this covers all cases correctly, 
including emacs-mode-string, and without causing any backward 
compatibility issues since the show-mode-in-prompt behavior is unchanged 
if set.  Would you consider applying this?

-Rob

readline-mode-strings.patch
Description: Text document