Merge from origin/emacs-27

1dfc497fac Minor wording change in Introduction to Programming in Ema...
ff09b4eeac Fix 'flymake-show-diagnostics-buffer' when line numbers ar...
63e8d0ea87 Fix last changes describing mail commands
01212a762f Do setup Flymake in file-less Elisp buffers
36873ef2b2 Fix error message for ‘cl-struct-unknown-slot’ (bug#39995)
3f9310b0fe Fix and improve documentation of mail-related features
1482a75efa Fix build failure with Fx_gtk_debug
cf57663f2a Mention jit-lock deferred as an alternative to fast-but-im...

# Conflicts:
#	etc/NEWS

5 files changed, 47 insertions, 36 deletions

diff --git a/lisp/emacs-lisp/cl-macs.el b/lisp/emacs-lisp/cl-macs.el
index 45a308ebcac..bb10194a946 100644
--- a/lisp/emacs-lisp/cl-macs.el
+++ b/lisp/emacs-lisp/cl-macs.el
@@ -3118,7 +3118,7 @@ slots skipped by :initial-offset may appear in the list."
               descs)))
     (nreverse descs)))
 
-(define-error 'cl-struct-unknown-slot "struct %S has no slot %S")
+(define-error 'cl-struct-unknown-slot "struct has no slot")
 
 (defun cl-struct-slot-offset (struct-type slot-name)
   "Return the offset of slot SLOT-NAME in STRUCT-TYPE.
diff --git a/lisp/mail/sendmail.el b/lisp/mail/sendmail.el
index 14adb5a195d..65d598c3bac 100644
--- a/lisp/mail/sendmail.el
+++ b/lisp/mail/sendmail.el
@@ -73,7 +73,7 @@ Otherwise, most addresses look like `angles', but they look like
   :version "27.1")
 (make-obsolete-variable
  'mail-from-style
- "only the `angles' value is valid according to RFC2822." "27.1" 'set)
+ "only the `angles' value is valid according to RFC5322." "27.1" 'set)
 
 ;;;###autoload
 (defcustom mail-specify-envelope-from nil
diff --git a/lisp/progmodes/elisp-mode.el b/lisp/progmodes/elisp-mode.el
index 20ec370dcb6..f85fd771ca8 100644
--- a/lisp/progmodes/elisp-mode.el
+++ b/lisp/progmodes/elisp-mode.el
@@ -291,9 +291,9 @@ Blank lines separate paragraphs.  Semicolons start comments.
   (unless
       (let* ((bfname (buffer-file-name))
              (fname (and (stringp bfname) (file-name-nondirectory bfname))))
-        (or (not (stringp fname))
-            (string-match "\\`\\.#" fname)
-            (string-equal dir-locals-file fname)))
+        (and (stringp fname)
+             (or (string-match "\\`\\.#" fname)
+                 (string-equal dir-locals-file fname))))
     (add-hook 'flymake-diagnostic-functions #'elisp-flymake-checkdoc nil t)
     (add-hook 'flymake-diagnostic-functions
               #'elisp-flymake-byte-compile nil t)))
diff --git a/lisp/progmodes/flymake.el b/lisp/progmodes/flymake.el
index 25a2152f005..7fca9dac1af 100644
--- a/lisp/progmodes/flymake.el
+++ b/lisp/progmodes/flymake.el
@@ -1321,35 +1321,42 @@ POS can be a buffer position or a button"
    (flymake-show-diagnostic (if (button-type pos) (button-start pos) pos))))
 
 (defun flymake--diagnostics-buffer-entries ()
-  (with-current-buffer flymake--diagnostics-buffer-source
-    (cl-loop for diag in
-             (cl-sort (flymake-diagnostics) #'< :key #'flymake-diagnostic-beg)
-             for (line . col) =
-             (save-excursion
-               (goto-char (flymake--diag-beg diag))
-               (cons (line-number-at-pos)
-                     (- (point)
-                        (line-beginning-position))))
-             for type = (flymake--diag-type diag)
-             collect
-             (list (list :diagnostic diag
-                         :line line
-                         :severity (flymake--lookup-type-property
-                                    type
-                                    'severity (warning-numeric-level :error)))
-                   `[,(format "%s" line)
-                     ,(format "%s" col)
-                     ,(propertize (format "%s"
-                                          (flymake--lookup-type-property
-                                           type 'flymake-type-name type))
-                                  'face (flymake--lookup-type-property
-                                         type 'mode-line-face 'flymake-error))
-                     (,(format "%s" (flymake--diag-text diag))
-                      mouse-face highlight
-                      help-echo "mouse-2: visit this diagnostic"
-                      face nil
-                      action flymake-goto-diagnostic
-                      mouse-action flymake-goto-diagnostic)]))))
+  ;; Do nothing if 'flymake--diagnostics-buffer-source' has not yet
+  ;; been set to a valid buffer.  This could happen when this function
+  ;; is called too early.  For example 'global-display-line-numbers-mode'
+  ;; calls us from its mode hook, when the diagnostic buffer has just
+  ;; been created by 'flymake-show-diagnostics-buffer', but is not yet
+  ;; set up properly.
+  (when (bufferp flymake--diagnostics-buffer-source)
+    (with-current-buffer flymake--diagnostics-buffer-source
+      (cl-loop for diag in
+               (cl-sort (flymake-diagnostics) #'< :key #'flymake-diagnostic-beg)
+               for (line . col) =
+               (save-excursion
+                 (goto-char (flymake--diag-beg diag))
+                 (cons (line-number-at-pos)
+                       (- (point)
+                          (line-beginning-position))))
+               for type = (flymake--diag-type diag)
+               collect
+               (list (list :diagnostic diag
+                           :line line
+                           :severity (flymake--lookup-type-property
+                                      type
+                                      'severity (warning-numeric-level :error)))
+                     `[,(format "%s" line)
+                       ,(format "%s" col)
+                       ,(propertize (format "%s"
+                                            (flymake--lookup-type-property
+                                             type 'flymake-type-name type))
+                                    'face (flymake--lookup-type-property
+                                           type 'mode-line-face 'flymake-error))
+                       (,(format "%s" (flymake--diag-text diag))
+                        mouse-face highlight
+                        help-echo "mouse-2: visit this diagnostic"
+                        face nil
+                        action flymake-goto-diagnostic
+                        mouse-action flymake-goto-diagnostic)])))))
 
 (define-derived-mode flymake-diagnostics-buffer-mode tabulated-list-mode
   "Flymake diagnostics"
diff --git a/lisp/simple.el b/lisp/simple.el
index 91736a60730..7c8ac413d35 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -8057,8 +8057,12 @@ OTHER-HEADERS is an alist specifying additional
 header fields.  Elements look like (HEADER . VALUE) where both
 HEADER and VALUE are strings.
 
-CONTINUE, if non-nil, says to continue editing a message already
-being composed.  Interactively, CONTINUE is the prefix argument.
+By default, if an unsent message is already being composed, this
+command will ask whether to erase the unsent message, and will not
+start a new message if the user doesn't allow erasing.  However, if
+CONTINUE is non-nil, it means to continue editing a message already
+being composed without asking.  Interactively, CONTINUE is the prefix
+argument.
 
 SWITCH-FUNCTION, if non-nil, is a function to use to
 switch to and display the buffer used for mail composition.