Stop keeping multiple doc copies for items defined multiple times

It was always a nuisance to keep all the copies in sync.
* src/doc.c (Fsnarf_documentation): Don't skip entire files.
Instead, skip individual doc strings starting with "SKIP".
* doc/lispref/internals.texi (Writing Emacs Primitives):
Mention this skipping.
* lisp/term/ns-win.el, lisp/term/pc-win.el, src/dosfns.c:
* src/frame.c, src/nsfns.m, src/nsmenu.m, src/nsterm.m:
* src/w16select.c, src/w32fns.c, src/w32menu.c, src/w32select.c:
* src/w32term.c, src/xmenu.c: Remove duplicated doc strings.
* src/xfns.c: Merge in information from doc string duplicates.

1 files changed, 16 insertions, 26 deletions

diff --git a/src/doc.c b/src/doc.c
index 3424bffdf9a..4264ed50640 100644
--- a/src/doc.c
+++ b/src/doc.c
@@ -535,7 +535,6 @@ the same file name is found in the `doc-directory'.  */)
   EMACS_INT pos;
   Lisp_Object sym;
   char *p, *name;
-  bool skip_file = 0;
   ptrdiff_t count;
   char const *dirname;
   ptrdiff_t dirlen;
@@ -609,34 +608,24 @@ the same file name is found in the `doc-directory'.  */)
         {
           end = strchr (p, '\n');
 
-          /* See if this is a file name, and if it is a file in build-files.  */
-          if (p[1] == 'S')
-            {
-              skip_file = 0;
-              if (end - p > 4 && end[-2] == '.'
-                  && (end[-1] == 'o' || end[-1] == 'c'))
-                {
-                  ptrdiff_t len = end - p - 2;
-                  char *fromfile = SAFE_ALLOCA (len + 1);
-                  memcpy (fromfile, &p[2], len);
-                  fromfile[len] = 0;
-                  if (fromfile[len-1] == 'c')
-                    fromfile[len-1] = 'o';
-
-                  skip_file = NILP (Fmember (build_string (fromfile),
-                                             Vbuild_files));
-                }
-            }
+          /* We used to skip files not in build_files, so that when a
+             function was defined several times in different files
+             (typically, once in xterm, once in w32term, ...), we only
+             paid attention to the relevant one.
+
+             But this meant the doc had to be kept and updated in
+             multiple files.  Nowadays we keep the doc only in eg xterm.
+             The (f)boundp checks below ensure we don't report
+             docs for eg w32-specific items on X.
+          */
 
           sym = oblookup (Vobarray, p + 2,
                           multibyte_chars_in_text ((unsigned char *) p + 2,
                                                    end - p - 2),
                           end - p - 2);
-          /* Check skip_file so that when a function is defined several
-             times in different files (typically, once in xterm, once in
-             w32term, ...), we only pay attention to the one that
-             matters.  */
-          if (! skip_file && SYMBOLP (sym))
+          /* Ignore docs that start with SKIP.  These mark
+             placeholders where the real doc is elsewhere.  */
+          if (SYMBOLP (sym))
             {
               /* Attach a docstring to a variable?  */
               if (p[1] == 'V')
@@ -644,8 +633,9 @@ the same file name is found in the `doc-directory'.  */)
                   /* Install file-position as variable-documentation property
                      and make it negative for a user-variable
                      (doc starts with a `*').  */
-                  if (!NILP (Fboundp (sym))
+                  if ((!NILP (Fboundp (sym))
                       || !NILP (Fmemq (sym, delayed_init)))
+                      && strncmp (end, "\nSKIP", 5))
                     Fput (sym, Qvariable_documentation,
                           make_number ((pos + end + 1 - buf)
                                        * (end[1] == '*' ? -1 : 1)));
@@ -654,7 +644,7 @@ the same file name is found in the `doc-directory'.  */)
               /* Attach a docstring to a function?  */
               else if (p[1] == 'F')
                 {
-                  if (!NILP (Ffboundp (sym)))
+                  if (!NILP (Ffboundp (sym)) && strncmp (end, "\nSKIP", 5))
                     store_function_docstring (sym, pos + end + 1 - buf);
                 }
               else if (p[1] == 'S')