Make HIST arg of read-from-minibuffer work with buffer-local vars

* lisp/simple.el (minibuffer-history-values): New function, should be
used to access the minibuffer input history variable when the
minibuffer might be active.  If the variable is buffer-local, the
previous buffer's value will be used.
(goto-history-element): Use the new function to access the minibuffer
history.
(minibuffer-history-isearch-wrap): Use the new function to access the
minibuffer history.
* src/minibuf.c (read_minibuf): Switch to previous buffer temporarily
before updating history list (Bug#38317).
(read-from-minibuffer): Extend documentation to mention that the
result of using the command will be added to the history list by
default.
* doc/lispref/minibuf.texi (Minibuffer History): Mention the
possibility of using a buffer-local variable as history.
* etc/NEWS: Announce changes.

1 files changed, 2 insertions, 1 deletions

diff --git a/doc/lispref/minibuf.texi b/doc/lispref/minibuf.texi
index 4a218fe7378..dde30ce67f7 100644
--- a/doc/lispref/minibuf.texi
+++ b/doc/lispref/minibuf.texi
@@ -547,7 +547,8 @@ to the minibuffer input function (@pxref{Initial Input}).
   If you don't specify @var{history}, then the default history list
 @code{minibuffer-history} is used.  For other standard history lists,
 see below.  You can also create your own history list variable; just
-initialize it to @code{nil} before the first use.
+initialize it to @code{nil} before the first use.  If the variable is
+buffer local, then each buffer will have its own input history list.
 
   Both @code{read-from-minibuffer} and @code{completing-read} add new
 elements to the history list automatically, and provide commands to