* lisp/emacs-lisp/lisp-mode.el: Add new indentation convention

(calculate-lisp-indent): To distinguish code and data when indenting,
introduce the convention that a space between an open paren and
a symbol indicate that this should be indented as a simple data list.

4 files changed, 20 insertions, 2 deletions

diff --git a/etc/NEWS b/etc/NEWS
index cb17a93f069..64cf0abbdb4 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -128,6 +128,10 @@ displayed and which are kept hidden.
 ** Emacs Lisp mode
 
 *** The mode-line now indicates whether we're using lexical or dynamic scoping.
+*** A space between an open paren and a symbol changes the indentation rule.
+The presence of a space between an open paren and a symbol now is
+taken as a statement by the programmer that this should be indented
+as a data list rather than as a piece of code.
 
 ** Dired
 
diff --git a/lisp/emacs-lisp/lisp-mode.el b/lisp/emacs-lisp/lisp-mode.el
index 7098a41f274..1311d94cb01 100644
--- a/lisp/emacs-lisp/lisp-mode.el
+++ b/lisp/emacs-lisp/lisp-mode.el
@@ -956,6 +956,7 @@ is the buffer position of the start of the containing expression."
           ;; setting this to a number inhibits calling hook
           (desired-indent nil)
           (retry t)
+          whitespace-after-open-paren
           calculate-lisp-indent-last-sexp containing-sexp)
       (cond ((or (markerp parse-start) (integerp parse-start))
              (goto-char parse-start))
@@ -985,6 +986,7 @@ is the buffer position of the start of the containing expression."
           nil
         ;; Innermost containing sexp found
         (goto-char (1+ containing-sexp))
+        (setq whitespace-after-open-paren (looking-at (rx whitespace)))
         (if (not calculate-lisp-indent-last-sexp)
             ;; indent-point immediately follows open paren.
             ;; Don't call hook.
@@ -999,9 +1001,11 @@ is the buffer position of the start of the containing expression."
                     calculate-lisp-indent-last-sexp)
                  ;; This is the first line to start within the containing sexp.
                  ;; It's almost certainly a function call.
-                 (if (= (point) calculate-lisp-indent-last-sexp)
+                 (if (or (= (point) calculate-lisp-indent-last-sexp)
+                         whitespace-after-open-paren)
                      ;; Containing sexp has nothing before this line
-                     ;; except the first element.  Indent under that element.
+                     ;; except the first element, or the first element is
+                     ;; preceded by whitespace.  Indent under that element.
                      nil
                    ;; Skip the first element, find start of second (the first
                    ;; argument of the function call) and indent under.
diff --git a/test/manual/indent/elisp.el b/test/manual/indent/elisp.el
new file mode 100644
index 00000000000..f3874b5c3e0
--- /dev/null
+++ b/test/manual/indent/elisp.el
@@ -0,0 +1,5 @@
+(defun x ()
+  (print (quote ( thingy great
+                  stuff)))
+  (print (quote (thingy great
+                        stuff))))
diff --git a/test/manual/indent/lisp.lisp b/test/manual/indent/lisp.lisp
new file mode 100644
index 00000000000..f3874b5c3e0
--- /dev/null
+++ b/test/manual/indent/lisp.lisp
@@ -0,0 +1,5 @@
+(defun x ()
+  (print (quote ( thingy great
+                  stuff)))
+  (print (quote (thingy great
+                        stuff))))