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, 18 insertions, 2 deletions

diff --git a/src/minibuf.c b/src/minibuf.c
index 1e87c5044af..bdae01dbc58 100644
--- a/src/minibuf.c
+++ b/src/minibuf.c
@@ -353,7 +353,7 @@ read_minibuf (Lisp_Object map, Lisp_Object initial, Lisp_Object prompt,
               Lisp_Object histvar, Lisp_Object histpos, Lisp_Object defalt,
               bool allow_props, bool inherit_input_method)
 {
-  Lisp_Object val;
+  Lisp_Object val, previous_buffer = Fcurrent_buffer ();
   ptrdiff_t count = SPECPDL_INDEX ();
   Lisp_Object mini_frame, ambient_dir, minibuffer, input_method;
   Lisp_Object enable_multibyte;
@@ -698,7 +698,20 @@ read_minibuf (Lisp_Object map, Lisp_Object initial, Lisp_Object prompt,
 
   /* Add the value to the appropriate history list, if any.  */
   if (! (NILP (Vhistory_add_new_input) || NILP (histstring)))
-    call2 (intern ("add-to-history"), Vminibuffer_history_variable, histstring);
+    {
+      ptrdiff_t count2 = SPECPDL_INDEX ();
+
+      /* If possible, switch back to the previous buffer first, in
+         case the history variable is buffer-local.  */
+      if (BUFFER_LIVE_P (XBUFFER (previous_buffer)))
+        {
+          record_unwind_current_buffer ();
+          Fset_buffer (previous_buffer);
+        }
+
+      call2 (intern ("add-to-history"), Vminibuffer_history_variable, histstring);
+      unbind_to (count2, Qnil);
+    }
 
   /* If Lisp form desired instead of string, parse it.  */
   if (expflag)
@@ -879,6 +892,9 @@ Fifth arg HIST, if non-nil, specifies a history list and optionally
   starting from 1 at the beginning of the list.  If HIST is the symbol
   `t', history is not recorded.
 
+  If `history-add-new-input' is non-nil (the default), the result will
+  be added to the history list using `add-to-history'.
+
 Sixth arg DEFAULT-VALUE, if non-nil, should be a string, which is used
   as the default to `read' if READ is non-nil and the user enters
   empty input.  But if READ is nil, this function does _not_ return