Backport CL148346 from upstream: --no-canonical-prefixes

gcc/gcc/gcc.c

Index: gcc/gcc/gcc.c
diff --git a/gcc/gcc/gcc.c b/gcc/gcc/gcc.c
index 103a8a1fc2a8fe549a62c156d0b15b07b4583fe5..5ef245e4e891fe69ffd54f32970ee62750cf5f39 100644
--- a/gcc/gcc/gcc.c
+++ b/gcc/gcc/gcc.c
@@ -1136,6 +1136,7 @@ static const struct option_map option_map[] =
    {"--library-directory", "-L", "a"},
    {"--machine", "-m", "aj"},
    {"--machine-", "-m", "*j"},
+   {"--no-canonical-prefixes", "-no-canonical-prefixes", 0},
    {"--no-integrated-cpp", "-no-integrated-cpp", 0},
    {"--no-line-commands", "-P", 0},
    {"--no-precompiled-includes", "-noprecomp", 0},
@@ -3255,6 +3256,9 @@ display_help (void)
   fputs (_("  -Xlinker <arg>           Pass <arg> on to the linker\n"), stdout);
   fputs (_("  -combine                 Pass multiple source files to compiler at once\n"), stdout);
   fputs (_("  -save-temps              Do not delete intermediate files\n"), stdout);
+  fputs (_("\
+  -no-canonical-prefixes   Do not canonicalize paths when building relative\n\
+                           prefixes to other gcc components\n"), stdout);
   fputs (_("  -pipe                    Use pipes rather than intermediate files\n"), stdout);
   fputs (_("  -time                    Time the execution of each subprocess\n"), stdout);
   fputs (_("  -specs=<file>            Override built-in specs with the contents of <file>\n"), stdout);
@@ -3347,6 +3351,8 @@ process_command (int argc, const char **argv)
   unsigned int j;
 #endif
   const char *tooldir_prefix;
+  char *(*get_relative_prefix) (const char *, const char *,
+				const char *) = NULL;
 
   GET_ENVIRONMENT (gcc_exec_prefix, "GCC_EXEC_PREFIX");
 
@@ -3442,6 +3448,27 @@ process_command (int argc, const char **argv)
       exit (status);
     }
 
+  /* Convert new-style -- options to old-style.  */
+  translate_options (&argc, (const char *const **) &argv);
+
+  /* Do language-specific adjustment/addition of flags.  */
+  lang_specific_driver (&argc, (const char *const **) &argv, &added_libraries);
+
+  /* Handle any -no-canonical-prefixes flag early, to assign the function
+     that builds relative prefixes.  This function creates default search
+     paths that are needed later in normal option handling.  */
+
+  for (i = 1; i < argc; i++)
+    {
+      if (! strcmp (argv[i], "-no-canonical-prefixes"))
+	{
+	  get_relative_prefix = make_relative_prefix_ignore_links;
+	  break;
+	}
+    }
+  if (! get_relative_prefix)
+    get_relative_prefix = make_relative_prefix;
+
   /* Set up the default search paths.  If there is no GCC_EXEC_PREFIX,
      see if we can create it from the pathname specified in argv[0].  */
 
@@ -3450,11 +3477,12 @@ process_command (int argc, const char **argv)
   /* FIXME: make_relative_prefix doesn't yet work for VMS.  */
   if (!gcc_exec_prefix)
     {
-      gcc_exec_prefix = make_relative_prefix (argv[0], standard_bindir_prefix,
-					      standard_exec_prefix);
-      gcc_libexec_prefix = make_relative_prefix (argv[0],
-						 standard_bindir_prefix,
-						 standard_libexec_prefix);
+      gcc_exec_prefix = get_relative_prefix (argv[0],
+					     standard_bindir_prefix,
+					     standard_exec_prefix);
+      gcc_libexec_prefix = get_relative_prefix (argv[0],
+					     standard_bindir_prefix,
+					     standard_libexec_prefix);
       if (gcc_exec_prefix)
 	xputenv (concat ("GCC_EXEC_PREFIX=", gcc_exec_prefix, NULL));
     }
@@ -3465,9 +3493,9 @@ process_command (int argc, const char **argv)
 	 / (which is ignored by make_relative_prefix), so append a
 	 program name.  */
       char *tmp_prefix = concat (gcc_exec_prefix, "gcc", NULL);
-      gcc_libexec_prefix = make_relative_prefix (tmp_prefix,
-						 standard_exec_prefix,
-						 standard_libexec_prefix);
+      gcc_libexec_prefix = get_relative_prefix (tmp_prefix,
+						standard_exec_prefix,
+						standard_libexec_prefix);
 
       /* The path is unrelocated, so fallback to the original setting.  */
       if (!gcc_libexec_prefix)
@@ -3605,12 +3633,6 @@ process_command (int argc, const char **argv)
 	}
     }
 
-  /* Convert new-style -- options to old-style.  */
-  translate_options (&argc, (const char *const **) &argv);
-
-  /* Do language-specific adjustment/addition of flags.  */
-  lang_specific_driver (&argc, (const char *const **) &argv, &added_libraries);
-
   /* Scan argv twice.  Here, the first time, just count how many switches
      there will be in their vector, and how many input files in theirs.
      Here we also parse the switches that cc itself uses (e.g. -v).  */
@@ -3794,6 +3816,9 @@ warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\n"
 	  save_temps_flag = 1;
 	  n_switches++;
 	}
+      else if (strcmp (argv[i], "-no-canonical-prefixes") == 0)
+	/* Already handled as a special case, so ignored here.  */
+	;
       else if (strcmp (argv[i], "-combine") == 0)
 	{
 	  combine_flag = 1;
@@ -4091,9 +4116,9 @@ warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\n"
      ``make_relative_prefix'' is not compiled for VMS, so don't call it.  */
   if (target_system_root && gcc_exec_prefix)
     {
-      char *tmp_prefix = make_relative_prefix (argv[0],
-					       standard_bindir_prefix,
-					       target_system_root);
+      char *tmp_prefix = get_relative_prefix (argv[0],
+					      standard_bindir_prefix,
+					      target_system_root);
       if (tmp_prefix && access_check (tmp_prefix, F_OK) == 0)
 	{
 	  target_system_root = tmp_prefix;
@@ -4135,6 +4160,8 @@ warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\n"
 	;
       else if (! strncmp (argv[i], "-Wp,", 4))
 	;
+      else if (! strcmp (argv[i], "-no-canonical-prefixes"))
+	;
       else if (! strcmp (argv[i], "-pass-exit-codes"))
 	;
       else if (! strcmp (argv[i], "-print-search-dirs"))