Fix return value of `defun' and un-define it.

* src/data.c (Fdefalias): Return `symbol'.
* doc/lispref/functions.texi (Defining Functions):
* doc/lispref/macros.texi (Defining Macros): Un-define the return value of
`defun', `defmacro' and `defalias'.

Fixes: debbugs:11686

2 files changed, 26 insertions, 17 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 9a239de5b99..080748236b4 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,8 +1,12 @@
+2012-06-18  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * data.c (Fdefalias): Return `symbol' (bug#11686).
+
 2012-06-18  Martin Rudalics  <rudalics@gmx.at>
 
         * buffer.c (Fkill_buffer): Don't throw an error when the buffer
-        gets killed during executing of this function (Bug#11665).  Try
-        to always return Qt when the buffer has been actually killed.
+        gets killed during executing of this function (Bug#11665).
+        Try to always return Qt when the buffer has been actually killed.
         (Vkill_buffer_query_functions): In doc-string say that functions
         run by this hook should not change the current buffer.
 
@@ -56,8 +60,8 @@
         (x_draw_glyph_string): Use them.
         * xfaces.c (Qline, Qwave): New Lisp objects.
         (check_lface_attrs, merge_face_ref)
-        (Finternal_set_lisp_face_attribute, realize_x_face): Handle
-        wave-style underline face attributes.
+        (Finternal_set_lisp_face_attribute, realize_x_face):
+        Handle wave-style underline face attributes.
         * xterm.c (x_draw_underwave): New function.
         (x_draw_glyph_string): Use it.
 
@@ -130,8 +134,8 @@
 
 2012-06-16  Eli Zaretskii  <eliz@gnu.org>
 
-        * xdisp.c (set_cursor_from_row): Don't dereference glyphs_end.  If
-        all the glyphs of the glyph row came from strings, and we have no
+        * xdisp.c (set_cursor_from_row): Don't dereference glyphs_end.
+        If all the glyphs of the glyph row came from strings, and we have no
         cursor positioning clues, put the cursor on the first glyph of the
         row.
         (handle_face_prop): Use chunk-relative overlay string index when
@@ -164,8 +168,8 @@
         Simplify under the assumption that USE_2_TAGS_FOR_INTS is defined.
         (INTTYPEBITS): New macro, for clarity.
         (INTMASK, MOST_POSITIVE_FIXNUM): Use it.
-        (LISP_INT1_TAG, LISP_STRING_TAG, LISP_INT_TAG_P): Simplify
-        now that USE_LSB_TAG is always defined.
+        (LISP_INT1_TAG, LISP_STRING_TAG, LISP_INT_TAG_P):
+        Simplify now that USE_LSB_TAG is always defined.
         (TYPEMASK, XINT) [USE_LSB_TAG]: Remove unnecessary cast.
         (make_number) [!USE_LSB_TAG]: Use INTMASK; that's simpler.
 
@@ -183,11 +187,11 @@
         * lisp.h (Lisp_Object) [CHECK_LISP_OBJECT_TYPE]: Define as struct
         instead of union.
         (XLI, XIL): Define.
-        (XHASH, XTYPE, XINT, XUINT, make_number, XSET, XPNTR, XUNTAG): Use
-        them.
-        * emacs.c (gdb_use_struct): Renamed from gdb_use_union.
+        (XHASH, XTYPE, XINT, XUINT, make_number, XSET, XPNTR, XUNTAG):
+        Use them.
+        * emacs.c (gdb_use_struct): Rename from gdb_use_union.
         * .gdbinit: Check gdb_use_struct instead of gdb_use_union.
-        * alloc.c (widen_to_Lisp_Object): Removed.
+        * alloc.c (widen_to_Lisp_Object): Remove.
         (mark_memory): Use XIL instead of widen_to_Lisp_Object.
         * frame.c (delete_frame): Remove outdated comment.
         * w32fns.c (Fw32_register_hot_key): Use XLI instead of checking
diff --git a/src/data.c b/src/data.c
index 4449977dbe0..2aa27e65d77 100644
--- a/src/data.c
+++ b/src/data.c
@@ -637,8 +637,9 @@ DEFUN ("fset", Ffset, Sfset, 2, 2, 0,
     Fput (symbol, Qautoload, XCDR (function));
 
   XSYMBOL (symbol)->function = definition;
-  /* Handle automatic advice activation */
-  if (CONSP (XSYMBOL (symbol)->plist) && !NILP (Fget (symbol, Qad_advice_info)))
+  /* Handle automatic advice activation.  */
+  if (CONSP (XSYMBOL (symbol)->plist)
+      && !NILP (Fget (symbol, Qad_advice_info)))
     {
       call2 (Qad_activate_internal, symbol, Qnil);
       definition = XSYMBOL (symbol)->function;
@@ -647,11 +648,12 @@ DEFUN ("fset", Ffset, Sfset, 2, 2, 0,
 }
 
 DEFUN ("defalias", Fdefalias, Sdefalias, 2, 3, 0,
-       doc: /* Set SYMBOL's function definition to DEFINITION, and return DEFINITION.
+       doc: /* Set SYMBOL's function definition to DEFINITION.
 Associates the function with the current load file, if any.
 The optional third argument DOCSTRING specifies the documentation string
 for SYMBOL; if it is omitted or nil, SYMBOL uses the documentation string
-determined by DEFINITION.  */)
+determined by DEFINITION.
+The return value is undefined.  */)
   (register Lisp_Object symbol, Lisp_Object definition, Lisp_Object docstring)
 {
   CHECK_SYMBOL (symbol);
@@ -666,7 +668,10 @@ determined by DEFINITION.  */)
   LOADHIST_ATTACH (Fcons (Qdefun, symbol));
   if (!NILP (docstring))
     Fput (symbol, Qfunction_documentation, docstring);
-  return definition;
+  /* We used to return `definition', but now that `defun' and `defmacro' expand
+     to a call to `defalias', we return `symbol' for backward compatibility
+     (bug#11686).  */
+  return symbol;
 }
 
 DEFUN ("setplist", Fsetplist, Ssetplist, 2, 2, 0,