emacs-27 e0de9f3: Don't skip empty lines when fitting mini frame to buffer (Bug#44080)

[Martin Rudalics]

branch: emacs-27
commit e0de9f3295b4c46cb7198ec0b9634809d7b7a36d
Author: Clemens Radermacher <clemens.radermacher@posteo.de>
Commit: Martin Rudalics <rudalics@gmx.at>

    Don't skip empty lines when fitting mini frame to buffer (Bug#44080)
    
    * lisp/window.el (fit-mini-frame-to-buffer,
    window--resize-mini-frame, fit-frame-to-buffer,
    fit-frame-to-buffer-1): By default, fit a mini frame without skipping its
    buffer's leading or trailing empty lines.
    * src/frame.c (resize-mini-frames): Update doc-string.
    * lisp/cus-start.el (resize-mini-frames): Update for customize.
    * doc/lispref/minibuf.texi (resize-mini-frames): Update description.
---
 doc/lispref/minibuf.texi |  6 ++++--
 etc/NEWS                 |  8 ++++++++
 lisp/cus-start.el        |  4 ++--
 lisp/window.el           | 24 +++++++++++++++++++++---
 src/frame.c              |  2 +-
 5 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/doc/lispref/minibuf.texi b/doc/lispref/minibuf.texi
index ecab882..b955355 100644
--- a/doc/lispref/minibuf.texi
+++ b/doc/lispref/minibuf.texi
@@ -2445,8 +2445,10 @@ frame is the buffer whose contents will be shown the 
next time that
 window is redisplayed.  The function is expected to fit the frame to
 the buffer in some appropriate way.
 
-Any other non-@code{nil} value means to resize minibuffer-only frames
-by calling @code{fit-frame-to-buffer} (@pxref{Resizing Windows}).
+Any other non-@code{nil} value means to resize minibuffer-only frames by
+calling @code{fit-mini-frame-to-buffer}, a function that behaves like
+@code{fit-frame-to-buffer} (@pxref{Resizing Windows}) but does not strip
+leading or trailing empty lines from the buffer text.
 @end defopt
 
 
diff --git a/etc/NEWS b/etc/NEWS
index c3ee1cd..f0b5dd0 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -33,6 +33,14 @@ applies, and please also update docstrings as needed.
 This is a bug-fix release with no new features.
 
 
+* Lisp Changes in Emacs 27.2
+
+*** The behavior of the user option 'resize-mini-frames' has changed.
+If set to non-nil, resize the mini frame using the new function
+'fit-mini-frame-to-buffer' which won't skip leading or trailing empty
+lines of the buffer.
+
+
 * Editing Changes in Emacs 27.2
 
 
diff --git a/lisp/cus-start.el b/lisp/cus-start.el
index 6632687..1d34489 100644
--- a/lisp/cus-start.el
+++ b/lisp/cus-start.el
@@ -317,9 +317,9 @@ Leaving \"Default\" unchecked is equivalent with specifying 
a default of
              (resize-mini-frames
               frames (choice
                       (const :tag "Never" nil)
-                      (const :tag "Fit frame to buffer" t)
+                      (const :tag "Fit mini frame to buffer" t)
                       (function :tag "User-defined function"))
-               "27.1")
+               "27.2")
              (menu-bar-mode frames boolean nil
                            ;; FIXME?
                             ;; :initialize custom-initialize-default
diff --git a/lisp/window.el b/lisp/window.el
index 7b75495..48005fc 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -3406,7 +3406,7 @@ routines."
   "Resize minibuffer-only frame FRAME."
   (if (functionp resize-mini-frames)
       (funcall resize-mini-frames frame)
-    (fit-frame-to-buffer frame)))
+    (fit-mini-frame-to-buffer frame)))
 
 (defun window--sanitize-window-sizes (horizontal)
   "Assert that all windows on selected frame are large enough.
@@ -8762,6 +8762,14 @@ Return 0 otherwise."
 
 (declare-function tool-bar-height "xdisp.c" (&optional frame pixelwise))
 
+(defun fit-mini-frame-to-buffer (&optional frame)
+  "Adjust size of minibuffer FRAME to display its contents.
+FRAME should be a minibuffer-only frame and defaults to the
+selected one.  Unlike `fit-frame-to-buffer' FRAME will fit to the
+contents of its buffer with any leading or trailing empty lines
+included."
+  (fit-frame-to-buffer-1 frame))
+
 (defun fit-frame-to-buffer (&optional frame max-height min-height max-width 
min-width only)
   "Adjust size of FRAME to display the contents of its buffer exactly.
 FRAME can be any live frame and defaults to the selected one.
@@ -8780,8 +8788,18 @@ horizontally only.
 The new position and size of FRAME can be additionally determined
 by customizing the options `fit-frame-to-buffer-sizes' and
 `fit-frame-to-buffer-margins' or setting the corresponding
-parameters of FRAME."
+parameters of FRAME.
+
+Any leading or trailing empty lines of the buffer content are not
+considered."
   (interactive)
+  (fit-frame-to-buffer-1 frame max-height min-height max-width min-width only 
t t))
+
+(defun fit-frame-to-buffer-1 (&optional frame max-height min-height max-width 
min-width only from to)
+  "Helper function for `fit-frame-to-buffer'.
+FROM and TO are the buffer positions to determine the size to fit
+to, see `window-text-pixel-size'.  The remaining arguments are as
+for `fit-frame-to-buffer'."
   (unless (fboundp 'display-monitor-attributes-list)
     (user-error "Cannot resize frame in non-graphic Emacs"))
   (setq frame (window-normalize-frame frame))
@@ -8916,7 +8934,7 @@ parameters of FRAME."
            ;; Note: Currently, for a new frame the sizes of the header
            ;; and mode line may be estimated incorrectly
            (size
-            (window-text-pixel-size window t t max-width max-height))
+            (window-text-pixel-size window from to max-width max-height))
            (width (max (car size) min-width))
            (height (max (cdr size) min-height)))
       ;; Don't change height or width when the window's size is fixed
diff --git a/src/frame.c b/src/frame.c
index 2556069..adcc489 100644
--- a/src/frame.c
+++ b/src/frame.c
@@ -6204,7 +6204,7 @@ window of that frame is the buffer whose text will be 
eventually shown
 in the minibuffer window.
 
 Any other non-nil value means to resize minibuffer-only frames by
-calling `fit-frame-to-buffer'.  */);
+calling `fit-mini-frame-to-buffer'.  */);
   resize_mini_frames = Qnil;
 
   DEFVAR_LISP ("focus-follows-mouse", focus_follows_mouse,