Unconditionally reset load-path after dumping

* src/lread.c: (dump_path): Remove.
(load-path-default): Remove `changed' argument.
Do not set dump_path permanently.  Simplify.
(init_lread): Simplify.
(syms_of_lread): Remove dump_path.

* lisp/loadup.el (load-path): Warn if site-load or site-init changes it.
No more need to reset it when bootstrapping.

* doc/lispref/internals.texi (Building Emacs):
* doc/lispref/loading.texi (Library Search): Mention that site-load,
site-init cannot change load-path.

* INSTALL: No longer mention load-path and site-init/site-load.

* etc/NEWS: Mention this.

Fixes: debbugs:16107

2 files changed, 94 insertions, 131 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 4e8285e9530..0b0ed9452ee 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,12 @@
+2013-12-13  Glenn Morris  <rgm@gnu.org>
+
+        * lread.c: Unconditionally reset load-path after dumping.  (Bug#16107)
+        (dump_path): Remove.
+        (load-path-default): Remove `changed' argument.
+        Do not set dump_path permanently.  Simplify.
+        (init_lread): Simplify.
+        (syms_of_lread): Remove dump_path.
+
 2013-12-13  Dmitry Antipov  <dmantipov@yandex.ru>
 
         * alloc.c, font.c, font.h, ftfont.c, ftxfont.c, macfont.m,
diff --git a/src/lread.c b/src/lread.c
index a64f083a5ac..5d02b2bd20b 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -4128,10 +4128,6 @@ load_path_check (Lisp_Object lpath)
     }
 }
 
-/* Record the value of load-path used at the start of dumping
-   so we can see if the site changed it later during dumping.  */
-static Lisp_Object dump_path;
-
 /* Return the default load-path, to be used if EMACSLOADPATH is unset.
    This does not include the standard site-lisp directories
    under the installation prefix (i.e., PATH_SITELOADSEARCH),
@@ -4145,18 +4141,16 @@ static Lisp_Object dump_path;
    If purify-flag (ie dumping) just use PATH_DUMPLOADSEARCH.
    Otherwise use PATH_LOADSEARCH.
 
-   If !initialized, then just set dump_path and return PATH_DUMPLOADSEARCH.
-   If initialized, then if Vload_path != dump_path, return just Vload_path.
-   (Presumably the load-path has already been changed by something.
-   This can only be from a site-load file during dumping.)
+   If !initialized, then just return PATH_DUMPLOADSEARCH.
+   If initialized:
    If Vinstallation_directory is not nil (ie, running uninstalled):
    If installation-dir/lisp exists and not already a member,
    we must be running uninstalled.  Reset the load-path
    to just installation-dir/lisp.  (The default PATH_LOADSEARCH
    refers to the eventual installation directories.  Since we
    are not yet installed, we should not use them, even if they exist.)
-   If installation-dir/lisp does not exist, just add dump_path at the
-   end instead.
+   If installation-dir/lisp does not exist, just add
+   PATH_DUMPLOADSEARCH at the end instead.
    Add installation-dir/site-lisp (if !no_site_lisp, and exists
    and not already a member) at the front.
    If installation-dir != source-dir (ie running an uninstalled,
@@ -4165,7 +4159,7 @@ static Lisp_Object dump_path;
    check), then repeat the above steps for source-dir/lisp, site-lisp.  */
 
 static Lisp_Object
-load_path_default (bool changed)
+load_path_default ()
 {
   Lisp_Object lpath = Qnil;
   const char *normal;
@@ -4186,131 +4180,108 @@ load_path_default (bool changed)
 
   normal = NILP (Vpurify_flag) ? PATH_LOADSEARCH : PATH_DUMPLOADSEARCH;
 
-  /* In a dumped Emacs, we normally reset the value of Vload_path using
-     PATH_LOADSEARCH, since the value that was dumped uses lisp/ in
-     the source directory, instead of the path of the installed elisp
-     libraries.  However, if it appears that Vload_path has already been
-     changed from the default that was saved before dumping, don't
-     change it further.  Changes can only be due to site-lisp
-     files that were processed during dumping.  */
-  /* FIXME?  AFAICS, it does not make sense to change load-path in a
-     dumped site-lisp file, so maybe we should just drop this check.
-     E.g., if you add an element to load-path, you are going to be
-     adding it to PATH_DUMPLOADSEARCH, which refers to the source directory.
-     This will make no sense (and may not still exist) in an installed Emacs.
-     And the only change it is sensible to make to load-path is to add
-     something to the front, which you should do with configure's
-     --enable-locallisppath option if you really want to have it dumped.  */
   if (initialized)
     {
-      if (changed || NILP (Fequal (dump_path, Vload_path)))
-        {
-          /* Do not make any changes.  */
-          return Vload_path;
-        }
-      else
-        {
 #ifdef HAVE_NS
-          const char *loadpath = ns_load_path ();
-          lpath = decode_env_path (0, loadpath ? loadpath : normal, 0);
+      const char *loadpath = ns_load_path ();
+      lpath = decode_env_path (0, loadpath ? loadpath : normal, 0);
 #else
-          lpath = decode_env_path (0, normal, 0);
+      lpath = decode_env_path (0, normal, 0);
 #endif
-          if (!NILP (Vinstallation_directory))
+      if (!NILP (Vinstallation_directory))
+        {
+          Lisp_Object tem, tem1;
+
+          /* Add to the path the lisp subdir of the installation
+             dir, if it is accessible.  Note: in out-of-tree builds,
+             this directory is empty save for Makefile.  */
+          tem = Fexpand_file_name (build_string ("lisp"),
+                                   Vinstallation_directory);
+          tem1 = Ffile_accessible_directory_p (tem);
+          if (!NILP (tem1))
+            {
+              if (NILP (Fmember (tem, lpath)))
+                {
+                  /* We are running uninstalled.  The default load-path
+                     points to the eventual installed lisp directories.
+                     We should not use those now, even if they exist,
+                     so start over from a clean slate.  */
+                  lpath = list1 (tem);
+                }
+            }
+          else
+            /* That dir doesn't exist, so add the build-time
+               Lisp dirs instead.  */
             {
-              Lisp_Object tem, tem1;
+              Lisp_Object dump_path =
+                decode_env_path (0, PATH_DUMPLOADSEARCH, 0);
+              lpath = nconc2 (lpath, dump_path);
+            }
 
-              /* Add to the path the lisp subdir of the installation
-                 dir, if it is accessible.  Note: in out-of-tree builds,
-                 this directory is empty save for Makefile.  */
-              tem = Fexpand_file_name (build_string ("lisp"),
+          /* Add site-lisp under the installation dir, if it exists.  */
+          if (!no_site_lisp)
+            {
+              tem = Fexpand_file_name (build_string ("site-lisp"),
                                        Vinstallation_directory);
               tem1 = Ffile_accessible_directory_p (tem);
               if (!NILP (tem1))
                 {
                   if (NILP (Fmember (tem, lpath)))
-                    {
-                      /* We are running uninstalled.  The default load-path
-                         points to the eventual installed lisp directories.
-                         We should not use those now, even if they exist,
-                         so start over from a clean slate.  */
-                      lpath = list1 (tem);
-                    }
+                    lpath = Fcons (tem, lpath);
                 }
-              else
-                /* That dir doesn't exist, so add the build-time
-                   Lisp dirs instead.  */
-                lpath = nconc2 (lpath, dump_path);
+            }
 
-              /* Add site-lisp under the installation dir, if it exists.  */
-              if (!no_site_lisp)
-                {
-                  tem = Fexpand_file_name (build_string ("site-lisp"),
-                                           Vinstallation_directory);
-                  tem1 = Ffile_accessible_directory_p (tem);
-                  if (!NILP (tem1))
-                    {
-                      if (NILP (Fmember (tem, lpath)))
-                        lpath = Fcons (tem, lpath);
-                    }
-                }
+          /* If Emacs was not built in the source directory,
+             and it is run from where it was built, add to load-path
+             the lisp and site-lisp dirs under that directory.  */
 
-              /* If Emacs was not built in the source directory,
-                 and it is run from where it was built, add to load-path
-                 the lisp and site-lisp dirs under that directory.  */
+          if (NILP (Fequal (Vinstallation_directory, Vsource_directory)))
+            {
+              Lisp_Object tem2;
+
+              tem = Fexpand_file_name (build_string ("src/Makefile"),
+                                       Vinstallation_directory);
+              tem1 = Ffile_exists_p (tem);
 
-              if (NILP (Fequal (Vinstallation_directory, Vsource_directory)))
+              /* Don't be fooled if they moved the entire source tree
+                 AFTER dumping Emacs.  If the build directory is indeed
+                 different from the source dir, src/Makefile.in and
+                 src/Makefile will not be found together.  */
+              tem = Fexpand_file_name (build_string ("src/Makefile.in"),
+                                       Vinstallation_directory);
+              tem2 = Ffile_exists_p (tem);
+              if (!NILP (tem1) && NILP (tem2))
                 {
-                  Lisp_Object tem2;
-
-                  tem = Fexpand_file_name (build_string ("src/Makefile"),
-                                           Vinstallation_directory);
-                  tem1 = Ffile_exists_p (tem);
-
-                  /* Don't be fooled if they moved the entire source tree
-                     AFTER dumping Emacs.  If the build directory is indeed
-                     different from the source dir, src/Makefile.in and
-                     src/Makefile will not be found together.  */
-                  tem = Fexpand_file_name (build_string ("src/Makefile.in"),
-                                           Vinstallation_directory);
-                  tem2 = Ffile_exists_p (tem);
-                  if (!NILP (tem1) && NILP (tem2))
-                    {
-                      tem = Fexpand_file_name (build_string ("lisp"),
-                                               Vsource_directory);
+                  tem = Fexpand_file_name (build_string ("lisp"),
+                                           Vsource_directory);
 
-                      if (NILP (Fmember (tem, lpath)))
-                        lpath = Fcons (tem, lpath);
+                  if (NILP (Fmember (tem, lpath)))
+                    lpath = Fcons (tem, lpath);
 
-                      if (!no_site_lisp)
+                  if (!no_site_lisp)
+                    {
+                      tem = Fexpand_file_name (build_string ("site-lisp"),
+                                               Vsource_directory);
+                      tem1 = Ffile_accessible_directory_p (tem);
+                      if (!NILP (tem1))
                         {
-                          tem = Fexpand_file_name (build_string ("site-lisp"),
-                                                   Vsource_directory);
-                          tem1 = Ffile_accessible_directory_p (tem);
-                          if (!NILP (tem1))
-                            {
-                              if (NILP (Fmember (tem, lpath)))
-                                lpath = Fcons (tem, lpath);
-                            }
+                          if (NILP (Fmember (tem, lpath)))
+                            lpath = Fcons (tem, lpath);
                         }
                     }
-                } /* Vinstallation_directory != Vsource_directory */
-
-            } /* if Vinstallation_directory */
+                }
+            } /* Vinstallation_directory != Vsource_directory */
 
-        } /* if dump_path == Vload_path */
+        } /* if Vinstallation_directory */
     }
   else                          /* !initialized */
     {
       /* NORMAL refers to PATH_DUMPLOADSEARCH, ie the lisp dir in the
          source directory.  We used to add ../lisp (ie the lisp dir in
-         the build directory) at the front here, but that caused trouble
-         because it was copied from dump_path into Vload_path, above,
-         when Vinstallation_directory was non-nil.  It should not be
-         necessary, since in out of tree builds lisp/ is empty, save
+         the build directory) at the front here, but that should not
+         be necessary, since in out of tree builds lisp/ is empty, save
          for Makefile.  */
       lpath = decode_env_path (0, normal, 0);
-      dump_path = lpath;
     }
 #endif /* !CANNOT_DUMP */
 
@@ -4322,27 +4293,20 @@ init_lread (void)
 {
   /* First, set Vload_path.  */
 
-  /* NB: Do not change Vload_path before calling load_path_default,
-     since it may check it against dump_path.
-     (This behavior could be changed.)  */
-
   /* We explicitly ignore EMACSLOADPATH when dumping.  */
   if (NILP (Vpurify_flag) && egetenv ("EMACSLOADPATH"))
     {
-      Lisp_Object elpath = decode_env_path ("EMACSLOADPATH", 0, 1);
+      Vload_path = decode_env_path ("EMACSLOADPATH", 0, 1);
 
       /* Check (non-nil) user-supplied elements.  */
-      load_path_check (elpath);
+      load_path_check (Vload_path);
 
       /* If no nils in the environment variable, use as-is.
          Otherwise, replace any nils with the default.  */
-      if (NILP (Fmemq (Qnil, elpath)))
-        {
-          Vload_path = elpath;
-        }
-      else
+      if (! NILP (Fmemq (Qnil, Vload_path)))
         {
-          Lisp_Object elem, default_lpath = load_path_default (0);
+          Lisp_Object elem, elpath = Vload_path;
+          Lisp_Object default_lpath = load_path_default ();
 
           /* Check defaults, before adding site-lisp.  */
           load_path_check (default_lpath);
@@ -4372,13 +4336,7 @@ init_lread (void)
     }
   else                          /* Vpurify_flag || !EMACSLOADPATH */
     {
-#ifdef CANNOT_DUMP
-      bool changed = 0;
-#else
-      bool changed = initialized && NILP (Fequal (dump_path, Vload_path));
-#endif
-
-      Vload_path = load_path_default (changed);
+      Vload_path = load_path_default ();
 
       /* Check before adding site-lisp directories.
          The install should have created them, but they are not
@@ -4386,10 +4344,8 @@ init_lread (void)
          Or we might be running before installation.  */
       load_path_check (Vload_path);
 
-      /* Add the site-lisp directories at the front, unless the
-         load-path has already been changed.
-         FIXME?  Should we ignore changed here?  */
-      if (initialized && !no_site_lisp && !changed)
+      /* Add the site-lisp directories at the front.  */
+      if (initialized && !no_site_lisp)
         {
           Lisp_Object sitelisp;
           sitelisp = decode_env_path (0, PATH_SITELOADSEARCH, 0);
@@ -4694,8 +4650,6 @@ variables, this must be set in the first line of a file.  */);
   DEFSYM (Qdir_ok, "dir-ok");
   DEFSYM (Qdo_after_load_evaluation, "do-after-load-evaluation");
 
-  staticpro (&dump_path);
-
   staticpro (&read_objects);
   read_objects = Qnil;
   staticpro (&seen_list);