* emultempl/elf32.em (gld${EMULATION_NAME}_stat_needed): Warn if

it looks like we might be linking in two different versions of the
	same shared library.  Based on a patch from H J Lu <hjl@zoom.com>.

ld/ChangeLog

@@ -1,3 +1,9 @@
+Tue Feb 13 14:04:19 1996  Ian Lance Taylor  <ian@cygnus.com>
+
+	* emultempl/elf32.em (gld${EMULATION_NAME}_stat_needed): Warn if
+	it looks like we might be linking in two different versions of the
+	same shared library.  Based on a patch from H J Lu <hjl@zoom.com>.
+
 Thu Feb  8 19:25:54 1996  Ian Lance Taylor  <ian@cygnus.com>
 
 	* ldlang.c (lang_size_sections): Increment the section size when a

ld/emultempl/elf32.em

@@ -4,7 +4,7 @@ cat >e${EMULATION_NAME}.c <<EOF
 /* This file is is generated by a shell script.  DO NOT EDIT! */
 
 /* 32 bit ELF emulation code for ${EMULATION_NAME}
-   Copyright (C) 1991, 1993, 1994, 1995 Free Software Foundation, Inc.
+   Copyright (C) 1991, 93, 94, 95, 1996 Free Software Foundation, Inc.
    Written by Steve Chamberlain <sac@cygnus.com>
    ELF support by Ian Lance Taylor <ian@cygnus.com>
 
@@ -134,7 +134,7 @@ gld${EMULATION_NAME}_open_dynamic_archive (arch, search, entry)
 /* These variables are required to pass information back and forth
    between after_open and check_needed and stat_needed.  */
 
-static struct bfd_elf_link_needed_list *global_needed;
+static struct bfd_link_needed_list *global_needed;
 static struct stat global_stat;
 static boolean global_found;
 
@@ -143,7 +143,7 @@ static boolean global_found;
 static void
 gld${EMULATION_NAME}_after_open ()
 {
-  struct bfd_elf_link_needed_list *needed, *l;
+  struct bfd_link_needed_list *needed, *l;
 
   /* We only need to worry about this when doing a final link.  */
   if (link_info.relocateable || link_info.shared)
@@ -161,7 +161,7 @@ gld${EMULATION_NAME}_after_open ()
   needed = bfd_elf_get_needed_list (output_bfd, &link_info);
   for (l = needed; l != NULL; l = l->next)
     {
-      struct bfd_elf_link_needed_list *ll;
+      struct bfd_link_needed_list *ll;
       const char *lib_path;
       size_t len;
       search_dirs_type *search;
@@ -182,15 +182,31 @@ gld${EMULATION_NAME}_after_open ()
 
       /* We need to find this file and include the symbol table.  We
 	 want to search for the file in the same way that the dynamic
-	 linker will search.  That means that we want to use rpath,
+	 linker will search.  That means that we want to use
-	 then the environment variable LD_LIBRARY_PATH, then the
+	 rpath_link, rpath, then the environment variable
-	 linker script LIB_SEARCH_DIRS.  We do not search using the -L
+	 LD_LIBRARY_PATH (native only), then the linker script
-	 arguments.  */
+	 LIB_SEARCH_DIRS.  We do not search using the -L arguments.  */
+      if (gld${EMULATION_NAME}_search_needed (command_line.rpath_link,
+					      l->name))
+	continue;
       if (gld${EMULATION_NAME}_search_needed (command_line.rpath, l->name))
 	continue;
+      if (command_line.rpath_link == NULL
+	  && command_line.rpath == NULL)
+	{
+	  lib_path = (const char *) getenv ("LD_RUN_PATH");
+	  if (gld${EMULATION_NAME}_search_needed (lib_path, l->name))
+	    continue;
+	}
+EOF
+if [ "x${host}" = "x${target}" ] ; then
+cat >>e${EMULATION_NAME}.c <<EOF
       lib_path = (const char *) getenv ("LD_LIBRARY_PATH");
       if (gld${EMULATION_NAME}_search_needed (lib_path, l->name))
 	continue;
+EOF
+fi
+cat >>e${EMULATION_NAME}.c <<EOF
       len = strlen (l->name);
       for (search = search_head; search != NULL; search = search->next)
 	{
@@ -341,21 +357,55 @@ static void
 gld${EMULATION_NAME}_stat_needed (s)
      lang_input_statement_type *s;
 {
+  struct stat st;
+  const char *f, *g;
+
   if (global_found)
     return;
-  if (s->the_bfd != NULL)
+  if (s->the_bfd == NULL)
-    {
+    return;
-      struct stat st;
 
   if (bfd_stat (s->the_bfd, &st) != 0)
-	einfo ("%P:%B: bfd_stat failed: %E\n", s->the_bfd);
-      else
     {
+      einfo ("%P:%B: bfd_stat failed: %E\n", s->the_bfd);
+      return;
+    }
+
   if (st.st_dev == global_stat.st_dev
       && st.st_ino == global_stat.st_ino)
+    {
       global_found = true;
+      return;
     }
+
+  /* We issue a warning if it looks like we are including two
+     different versions of the same shared library.  For example,
+     there may be a problem if -lc picks up libc.so.6 but some other
+     shared library has a DT_NEEDED entry of libc.so.5.  */
+
+  if (strchr (global_needed->name, '/') != NULL)
+    return;
+
+  f = strrchr (s->filename, '/');
+  if (f != NULL)
+    ++f;
+  else
+    f = s->filename;
+  g = global_needed->name;
+
+  while (*f != '\0' && *f == *g)
+    {
+      ++f;
+      ++g;
     }
+
+  /* We have now skipped past the identical prefixes.  If the
+     remainder of both names is nothing but numbers and dots, we issue
+     a warning.  */
+  if (f[strspn (f, "0123456789.")] == '\0'
+      && g[strspn (g, "0123456789.")] == '\0')
+    einfo ("%P: warning: %s, needed by %B, may conflict with %s\n",
+	   global_needed->name, global_needed->by, s->filename);
 }
 
 /* This is called after the sections have been attached to output
@@ -364,6 +414,7 @@ gld${EMULATION_NAME}_stat_needed (s)
 static void
 gld${EMULATION_NAME}_before_allocation ()
 {
+  const char *rpath;
   asection *sinterp;
 
   /* If we are going to make any variable assignments, we need to let
@@ -373,9 +424,12 @@ gld${EMULATION_NAME}_before_allocation ()
 
   /* Let the ELF backend work out the sizes of any sections required
      by dynamic linking.  */
+  rpath = command_line.rpath;
+  if (rpath == NULL)
+    rpath = (const char *) getenv ("LD_RUN_PATH");
   if (! bfd_elf32_size_dynamic_sections (output_bfd,
 					 command_line.soname,
-					 command_line.rpath,
+					 rpath,
 					 command_line.export_dynamic,
 					 &link_info,
 					 &sinterp))