bug#34621: Patch Update

[Christopher Thorne]

Thanks for the input, Drew.

> It's not obvious what a reasonable or smart default
> filename pattern is in most cases.  Just because
> your current buffer is visiting a file does not at
> all imply that you want to search files with the
> same extension.
>
> I think you need to (for yourself) specify just
> what relation (if any) you want between the current
> buffer and the default filename pattern.

Personally I think the current behaviour of searching files with the 
same extension works quite well in most cases. There is also some 
flexibility with aliases which means that if you're in a "*.c" file the 
default pattern becomes "*.[ch]".

However, I like the idea of providing more flexibility like 
`grepp-default-regexp-fn`. This would mean a buffer in c-mode could 
always suggest *.[ch] regardless of its buffer/file name. More 
importantly, dired could implement this so that no default patterns are 
suggested for dired buffers.

I will consider both (1) using only buffer-file-name instead of 
buffer-name (2) enabling rgrep to delegate extension suggestions to 
major modes. (1) would fix the case I'm personally encountering with 
dired, but (2) may be better in the long term and could cover more cases 
that I'm currently imagining.