master ca55e4d: Make backslash characters no longer escape in `f90-mode'

[Lars Ingebrigtsen]

branch: master
commit ca55e4d89831cf25137e7d9df4110df16aab1800
Author: Lars Ingebrigtsen <larsi@gnus.org>
Commit: Lars Ingebrigtsen <larsi@gnus.org>

    Make backslash characters no longer escape in `f90-mode'
    
    * lisp/progmodes/f90.el (f90-backslash-not-special): Make obsolete
    (bug#32766).
    (f90-mode-syntax-table): Make the backslash be a normal
    (non-escape) character, which is the default since about 2007 (and
    F2K): https://gcc.gnu.org/bugzilla/show_bug.cgi?id=34203
---
 etc/NEWS              |  7 +++++++
 lisp/progmodes/f90.el | 11 +++++------
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index a376df6..7cdb9d9 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2010,6 +2010,13 @@ first).
 
 * Incompatible Editing Changes in Emacs 28.1
 
+** In 'f90-mode', the backslash character ('\') no longer escapes.
+For about a decade, the backslash character has no longer had a
+special escape syntax in Fortran F90.  To get the old behaviour back,
+say something like:
+
+    (modify-syntax-entry ?\\ "\\" f90-mode-syntax-table)
+
 ** In 'nroff-mode', 'center-line' is now bound to 'M-o M-s'.
 The original key binding was 'M-s', which interfered with I-search,
 since the latter uses 'M-s' as a prefix key of the search prefix map.
diff --git a/lisp/progmodes/f90.el b/lisp/progmodes/f90.el
index 92b165b..90678c8 100644
--- a/lisp/progmodes/f90.el
+++ b/lisp/progmodes/f90.el
@@ -718,10 +718,7 @@ Can be overridden by the value of 
`font-lock-maximum-decoration'.")
     (modify-syntax-entry ?*  "."  table)
     (modify-syntax-entry ?/  "."  table)
     (modify-syntax-entry ?%  "."  table) ; bug#8820
-    ;; I think that the f95 standard leaves the behavior of \
-    ;; unspecified, but that f2k will require it to be non-special.
-    ;; Use `f90-backslash-not-special' to change.
-    (modify-syntax-entry ?\\ "\\" table) ; escape chars
+    (modify-syntax-entry ?\\ "."  table)
     table)
   "Syntax table used in F90 mode.")
 
@@ -2395,9 +2392,11 @@ CHANGE-WORD should be one of `upcase-word', 
`downcase-word', `capitalize-word'."
 
 (defun f90-backslash-not-special (&optional all)
   "Make the backslash character (\\) be non-special in the current buffer.
+This is the default in `f90-mode'.
+
 With optional argument ALL, change the default for all present
-and future F90 buffers.  F90 mode normally treats backslash as an
-escape character."
+and future F90 buffers."
+  (declare (obsolete nil "28.1"))
   (or (derived-mode-p 'f90-mode)
       (user-error "This function should only be used in F90 buffers"))
   (when (equal (char-syntax ?\\ ) ?\\ )