RE: [External] : Re: History completion

[Drew Adams]

> >> Wouldn't it be nice to allow completion on previous input
> >> in the minibuffer.
> >
> > Yet another feature that Icicles introduced and has had since 2005...
> >
> > https://www.emacswiki.org/emacs/Icicles_-_History_Enhancements
> 
> What key does Icicles use to complete on the history?

The URL you quoted explains that there are 3 ways
complete against input history, and thus 3 keys.

`M-o', available any time the minibuffer is active
(so not just during input with completion), provides
a form of completion on demand.  It uses a recursive
minibuffer.  You can use it to insert any number of
previous inputs, using completion.  (And you can of
course combine completion with cycling among input
candidates.)  Insertion appends to your minibuffer
input, and you can edit the inserted text, of course.

A prefix arg with `M-o' determines whether to follow
an inserted previous with a space char, and whether
to enclose it with "...".

`M-h' and `M-<pause>' are used during completion.
They each provide completion against previous inputs
for the given (i.e., current) minibuffer history.
Neither uses a recursive minibuffer.  They just
co-opt the current completion to go against candidates
in the current history list.

`M-<pause>' restricts completion to previous inputs 
in the current set of matching candidates.  So you
can narrow the set in various ways before using it.

There are other differences between `M-h' and
`M-<pause>'.  Read the doc you cited for more info.