bug#38835: 27; Recreated *scratch* buffer has lexical-binding = nil

bug#38835: 27; Recreated *scratch* buffer has lexical-binding = nil

[Mattias Engdegård]

The standard *scratch* buffer is blessed with lexical-binding = t, but if killed and recreated via C-x b *scratch* RET, the new buffer isn't.

Not sure where this logic belongs; the *scratch* handling seems a bit spread out. In Fset_buffer_major_mode?

bug#38835: 27; Recreated *scratch* buffer has lexical-binding = nil

[Eli Zaretskii]

> From: Mattias Engdegård <mattiase@acm.org>
> Date: Tue, 31 Dec 2019 16:52:18 +0100
> 
> The standard *scratch* buffer is blessed with lexical-binding = t, but if killed and recreated via C-x b *scratch* RET, the new buffer isn't.
> 
> Not sure where this logic belongs; the *scratch* handling seems a bit spread out. In Fset_buffer_major_mode?

Maybe we should have a command to recreate *scratch*, and call it from
startup.el?  Then that command could do this.

Or maybe we should decide that lisp-interaction-mode should do this
for any buffer?

bug#38835: 27; Recreated *scratch* buffer has lexical-binding = nil

[martin rudalics]

 > Maybe we should have a command to recreate *scratch*, and call it from
 > startup.el?  Then that command could do this.

'other_buffer_safely' would need it too.

martin

bug#38835: 27; Recreated *scratch* buffer has lexical-binding = nil

[Mattias Engdegård]

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1 jan. 2020 kl. 17.14 skrev Eli Zaretskii <eliz@gnu.org>:

> Or maybe we should decide that lisp-interaction-mode should do this
> for any buffer?

Yes, that seems to be the best and simplest choice.  Patch OK for emacs-27?


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From e258f78fd1869d301d94ff555358591e49541d94 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mattias=20Engdeg=C3=A5rd?= <mattiase@acm.org>
Date: Mon, 13 Jan 2020 14:53:11 +0100
Subject: [PATCH] Always use lexical-binding in lisp-interaction-mode
 (bug#38835)

* lisp/progmodes/elisp-mode.el (lisp-interaction-mode):
Set lexical-binding.
* lisp/startup.el (command-line, startup--get-buffer-create-scratch):
Don't set lexical-binding here.
---
 lisp/progmodes/elisp-mode.el | 3 ++-
 lisp/startup.el              | 4 +---
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/lisp/progmodes/elisp-mode.el b/lisp/progmodes/elisp-mode.el
index 774e3324c2..2617a6e4cc 100644
--- a/lisp/progmodes/elisp-mode.el
+++ b/lisp/progmodes/elisp-mode.el
@@ -933,7 +933,8 @@ lisp-interaction-mode
 Semicolons start comments.
 
 \\{lisp-interaction-mode-map}"
-  :abbrev-table nil)
+  :abbrev-table nil
+  (setq-local lexical-binding t))
 
 ;;; Emacs Lisp Byte-Code mode
 
diff --git a/lisp/startup.el b/lisp/startup.el
index c27af726f9..2a85c004da 100644
--- a/lisp/startup.el
+++ b/lisp/startup.el
@@ -1435,8 +1435,7 @@ command-line
   (if (get-buffer "*scratch*")
       (with-current-buffer "*scratch*"
 	(if (eq major-mode 'fundamental-mode)
-	    (funcall initial-major-mode))
-        (setq-local lexical-binding t)))
+	    (funcall initial-major-mode))))
 
   ;; Load library for our terminal type.
   ;; User init file can set term-file-prefix to nil to prevent this.
@@ -2317,7 +2316,6 @@ startup--get-buffer-create-scratch
   (or (get-buffer "*scratch*")
       (with-current-buffer (get-buffer-create "*scratch*")
         (set-buffer-major-mode (current-buffer))
-        (setq-local lexical-binding t)
         (current-buffer))))
 
 (defun command-line-1 (args-left)
-- 
2.21.0 (Apple Git-122.2)

bug#38835: 27; Recreated *scratch* buffer has lexical-binding = nil

[Eli Zaretskii]

> From: Mattias Engdegård <mattiase@acm.org>
> Date: Mon, 13 Jan 2020 14:57:29 +0100
> Cc: 38835@debbugs.gnu.org
> 
> > Or maybe we should decide that lisp-interaction-mode should do this
> > for any buffer?
> 
> Yes, that seems to be the best and simplest choice.  Patch OK for emacs-27?

Yes, but this needs a NEWS entry, and please see if we say enough
about lisp-interaction-mode and/or lexical-binding to mention this in
the manual as well.

Thanks.

bug#38835: 27; Recreated *scratch* buffer has lexical-binding = nil

[Mattias Engdegård]

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13 jan. 2020 kl. 17.30 skrev Eli Zaretskii <eliz@gnu.org>:

> Yes, but this needs a NEWS entry, and please see if we say enough
> about lisp-interaction-mode and/or lexical-binding to mention this in
> the manual as well.

New patch. The existing NEWS entry was rephrased slightly, and a sentence added to the elisp manual.


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From d645628e3cf6ebe5eaea3b40100bd77b9c823f8b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mattias=20Engdeg=C3=A5rd?= <mattiase@acm.org>
Date: Mon, 13 Jan 2020 14:53:11 +0100
Subject: [PATCH] Always use lexical-binding in lisp-interaction-mode
 (bug#38835)

* lisp/progmodes/elisp-mode.el (lisp-interaction-mode):
Set lexical-binding.
* lisp/startup.el (command-line, startup--get-buffer-create-scratch):
Don't set lexical-binding here.
* doc/lispref/variables.texi:
* etc/NEWS:
Make it clear that lisp-interaction-mode uses lexical-binding.
---
 doc/lispref/variables.texi   | 3 +++
 etc/NEWS                     | 3 ++-
 lisp/progmodes/elisp-mode.el | 3 ++-
 lisp/startup.el              | 4 +---
 4 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/doc/lispref/variables.texi b/doc/lispref/variables.texi
index 1ec97e2f3d..1e357754ab 100644
--- a/doc/lispref/variables.texi
+++ b/doc/lispref/variables.texi
@@ -1187,6 +1187,9 @@ Using Lexical Binding
 lexical binding is enabled if the @var{lexical} argument to
 @code{eval} is non-@code{nil}.  @xref{Eval}.
 
+Lexical binding is also enabled in Lisp Interaction and IELM
+mode, used in the @file{*scratch*} and @file{*ielm*} buffers.
+
 @cindex special variables
   Even when lexical binding is enabled, certain variables will
 continue to be dynamically bound.  These are called @dfn{special
diff --git a/etc/NEWS b/etc/NEWS
index 61b9e4a723..031ddf5800 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -338,7 +338,8 @@ answers, but also function keys like 'F1', character events such as
 
 ** Lexical binding is now used when evaluating interactive Elisp forms.
 More specifically, lexical-binding is now used for 'M-:', '--eval', as
-well as in the "*scratch*" and "*ielm*" buffers.
+well as in lisp-interaction-mode and ielm-mode, used in the "*scratch*"
+and "*ielm*" buffers.
 
 ---
 ** The new user option 'tooltip-resize-echo-area' avoids truncating
diff --git a/lisp/progmodes/elisp-mode.el b/lisp/progmodes/elisp-mode.el
index 774e3324c2..2617a6e4cc 100644
--- a/lisp/progmodes/elisp-mode.el
+++ b/lisp/progmodes/elisp-mode.el
@@ -933,7 +933,8 @@ lisp-interaction-mode
 Semicolons start comments.
 
 \\{lisp-interaction-mode-map}"
-  :abbrev-table nil)
+  :abbrev-table nil
+  (setq-local lexical-binding t))
 
 ;;; Emacs Lisp Byte-Code mode
 
diff --git a/lisp/startup.el b/lisp/startup.el
index c27af726f9..2a85c004da 100644
--- a/lisp/startup.el
+++ b/lisp/startup.el
@@ -1435,8 +1435,7 @@ command-line
   (if (get-buffer "*scratch*")
       (with-current-buffer "*scratch*"
 	(if (eq major-mode 'fundamental-mode)
-	    (funcall initial-major-mode))
-        (setq-local lexical-binding t)))
+	    (funcall initial-major-mode))))
 
   ;; Load library for our terminal type.
   ;; User init file can set term-file-prefix to nil to prevent this.
@@ -2317,7 +2316,6 @@ startup--get-buffer-create-scratch
   (or (get-buffer "*scratch*")
       (with-current-buffer (get-buffer-create "*scratch*")
         (set-buffer-major-mode (current-buffer))
-        (setq-local lexical-binding t)
         (current-buffer))))
 
 (defun command-line-1 (args-left)
-- 
2.21.0 (Apple Git-122.2)

bug#38835: 27; Recreated *scratch* buffer has lexical-binding = nil

[Eli Zaretskii]

> From: Mattias Engdegård <mattiase@acm.org>
> Date: Mon, 13 Jan 2020 18:04:22 +0100
> Cc: rudalics@gmx.at, 38835@debbugs.gnu.org
> 
> > Yes, but this needs a NEWS entry, and please see if we say enough
> > about lisp-interaction-mode and/or lexical-binding to mention this in
> > the manual as well.
> 
> New patch. The existing NEWS entry was rephrased slightly, and a sentence added to the elisp manual.

Thanks, LGTM.

bug#38835: 27; Recreated *scratch* buffer has lexical-binding = nil

[Mattias Engdegård]

Thank you, pushed to emacs-27.