Fix breaking of rfc2047 headers with long words

* lisp/mail/rfc2047.el (rfc2047-fold-region): Don't break lines
right after the Header: field, but wait until the next
whitespace.  (This only makes a difference for words that are very
long (i.e., longer than, say, 60 characters, depending on the
header name length.)

2 files changed, 30 insertions, 15 deletions

diff --git a/lisp/mail/rfc2047.el b/lisp/mail/rfc2047.el
index 9de6f02edfb..e3315120d82 100644
--- a/lisp/mail/rfc2047.el
+++ b/lisp/mail/rfc2047.el
@@ -765,7 +765,9 @@ Point moves to the end of the region."
          ;; Whitespace -- possible break point.
 	 ((memq (char-after) '(?  ?\t))
 	  (skip-chars-forward " \t")
-	  (unless first ;; Don't break just after the header name.
+          ;; Don't break just after the header name.
+	  (if first
+              (setq first nil)
 	    (setq break (point))))
          ;; If the header has been encoded (with RFC2047 encoding,
          ;; which looks like "=?utf-8?Q?F=C3=B3?=".
@@ -780,8 +782,7 @@ Point moves to the end of the region."
 	    (skip-chars-forward "^ \t\n\r")))
          ;; Look for the next LWSP (i.e., whitespace character).
 	 (t
-	  (skip-chars-forward "^ \t\n\r")))
-	(setq first nil))
+	  (skip-chars-forward "^ \t\n\r"))))
       (when (and (or break qword-break)
 		 (> (- (point) bol) 76))
         ;; Finally, after the loop, we have a line longer than 76
diff --git a/test/lisp/mail/rfc2047-tests.el b/test/lisp/mail/rfc2047-tests.el
index 8f7b345e71e..bfaf9958917 100644
--- a/test/lisp/mail/rfc2047-tests.el
+++ b/test/lisp/mail/rfc2047-tests.el
@@ -22,25 +22,39 @@
 (require 'ert)
 (require 'rfc2047)
 
-(ert-deftest test-rfc2047-fold-short ()
+(defun test-rfc2047 (before after)
   (with-temp-buffer
-    (insert "Organization: Lots Of Short Words Here Lots Of Short Words Here Lots Of Short Words Here\n")
+    (insert before)
     (goto-char (point-min))
     (rfc2047-fold-field)
-    (should (equal (buffer-string)
-                   "Organization: Lots Of Short Words Here Lots Of Short Words Here Lots Of
+    (should (equal (buffer-string) after))))
+
+(ert-deftest test-rfc2047-fold-short ()
+  (test-rfc2047
+   "Organization: Lots Of Short Words Here Lots Of Short Words Here Lots Of Short Words Here\n"
+
+   "Organization: Lots Of Short Words Here Lots Of Short Words Here Lots Of
  Short Words Here
-"))))
+"))
 
 (ert-deftest test-rfc2047-fold-encoded ()
-  (with-temp-buffer
-    (insert "Subject: This is =?utf-8?Q?=C3=A1?= long subject that's =?utf-8?Q?v=C3=A9ry?= long and =?utf-8?Q?ver=C3=BD?= encoded yes indeed it =?utf-8?Q?=C3=ADs?=\n")
-    (goto-char (point-min))
-    (rfc2047-fold-field)
-    (should (equal (buffer-string)
-                   "Subject: This is =?utf-8?Q?=C3=A1?= long subject that's
+  (test-rfc2047
+   "Subject: This is =?utf-8?Q?=C3=A1?= long subject that's =?utf-8?Q?v=C3=A9ry?= long and =?utf-8?Q?ver=C3=BD?= encoded yes indeed it =?utf-8?Q?=C3=ADs?=\n"
+   "Subject: This is =?utf-8?Q?=C3=A1?= long subject that's
  =?utf-8?Q?v=C3=A9ry?= long and =?utf-8?Q?ver=C3=BD?= encoded yes indeed it
  =?utf-8?Q?=C3=ADs?=
-"))))
+"))
+
+(ert-deftest test-rfc2047-fold-long ()
+  (test-rfc2047
+   "Organization: verylongverylongverylongverylongverylongverylongverylongverylongverylongword and then\n"
+   "Organization: verylongverylongverylongverylongverylongverylongverylongverylongverylongword
+ and then
+"))
+
+(ert-deftest test-rfc2047-fold-long-short ()
+  (test-rfc2047
+   "Organization: verylongverylongverylongverylongverylongverylongverylongverylongverylongword\n"
+   "Organization: verylongverylongverylongverylongverylongverylongverylongverylongverylongword\n"))
 
 ;;; rfc2047-tests.el ends here