[Bug preprocessor/104471] ICE with -nostdinc: NULL directory in find_file

["pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104471

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This patch should fix the issue (I might get to it in a few weeks though):
diff --git a/libcpp/files.cc b/libcpp/files.cc
index a18b1caf48d..eb90fa4f65a 100644
--- a/libcpp/files.cc
+++ b/libcpp/files.cc
@@ -177,7 +177,7 @@ static bool read_file_guts (cpp_reader *pfile, _cpp_file
*file,
 static bool read_file (cpp_reader *pfile, _cpp_file *file,
                       location_t loc);
 static struct cpp_dir *search_path_head (cpp_reader *, const char *fname,
-                                int angle_brackets, enum include_type);
+                                int angle_brackets, enum include_type, bool =
true);
 static const char *dir_name_of_file (_cpp_file *file);
 static void open_file_failed (cpp_reader *pfile, _cpp_file *file, int,
                              location_t);
@@ -1026,7 +1026,7 @@ _cpp_mark_file_once_only (cpp_reader *pfile, _cpp_file
*file)
    nothing left in the path, returns NULL.  */
 static struct cpp_dir *
 search_path_head (cpp_reader *pfile, const char *fname, int angle_brackets,
-                 enum include_type type)
+                 enum include_type type, bool canerror)
 {
   cpp_dir *dir;
   _cpp_file *file;
@@ -1055,7 +1055,7 @@ search_path_head (cpp_reader *pfile, const char *fname,
int angle_brackets,
     return make_cpp_dir (pfile, dir_name_of_file (file),
                         pfile->buffer ? pfile->buffer->sysp : 0);

-  if (dir == NULL)
+  if (canerror && dir == NULL)
     cpp_error (pfile, CPP_DL_ERROR,
               "no include path in which to search for %s", fname);

@@ -2144,7 +2144,9 @@ bool
 _cpp_has_header (cpp_reader *pfile, const char *fname, int angle_brackets,
                 enum include_type type)
 {
-  cpp_dir *start_dir = search_path_head (pfile, fname, angle_brackets, type);
+  cpp_dir *start_dir = search_path_head (pfile, fname, angle_brackets, type,
false);
+  if (!start_dir)
+    return false;
   _cpp_file *file = _cpp_find_file (pfile, fname, start_dir, angle_brackets,
                                    _cpp_FFK_HAS_INCLUDE, 0);
   return file->err_no != ENOENT;