[Fortran] move more diagnostics to the common machinery (try 2)

Index: gcc/fortran/gfortran.h
===================================================================
--- gcc/fortran/gfortran.h	(revision 215880)
+++ gcc/fortran/gfortran.h	(working copy)
@@ -2693,17 +2693,19 @@  void gfc_buffer_error (int);
 
 const char *gfc_print_wide_char (gfc_char_t);
 
 void gfc_warning (const char *, ...) ATTRIBUTE_GCC_GFC(1,2);
 void gfc_warning_now (const char *, ...) ATTRIBUTE_GCC_GFC(1,2);
-void gfc_warning_cmdline (const char *gmsgid, ...) ATTRIBUTE_GCC_GFC(1,2);
+bool gfc_warning_cmdline (const char *gmsgid, ...) ATTRIBUTE_GCC_GFC(1,2);
+bool gfc_warning_cmdline (int opt, const char *gmsgid, ...) ATTRIBUTE_GCC_GFC(2,3);
 
 void gfc_clear_warning (void);
 void gfc_warning_check (void);
 
 void gfc_error (const char *, ...) ATTRIBUTE_GCC_GFC(1,2);
+void gfc_error_cmdline (const char *gmsgid, ...) ATTRIBUTE_GCC_GFC(1,2);
 void gfc_error_now (const char *, ...) ATTRIBUTE_GCC_GFC(1,2);
 void gfc_fatal_error (const char *, ...) ATTRIBUTE_NORETURN ATTRIBUTE_GCC_GFC(1,2);
 void gfc_internal_error (const char *, ...) ATTRIBUTE_NORETURN ATTRIBUTE_GCC_GFC(1,2);
 void gfc_clear_error (void);
 int gfc_error_check (void);
 int gfc_error_flag_test (void);
Index: gcc/fortran/error.c
===================================================================
--- gcc/fortran/error.c	(revision 215880)
+++ gcc/fortran/error.c	(working copy)
@@ -1050,25 +1109,61 @@  gfc_diagnostic_finalizer (diagnostic_con
 {
   pp_destroy_prefix (context->printer);
   pp_newline_and_flush (context->printer);
 }
 
 /* Give a warning about the command-line.  */
 
-void
+bool
+gfc_warning_cmdline (int opt, const char *gmsgid, ...)
+{
+  va_list argp;
+  diagnostic_info diagnostic;
+  bool ret;
+
+  va_start (argp, gmsgid);
+  diagnostic_set_info (&diagnostic, gmsgid, &argp, UNKNOWN_LOCATION,
+		       DK_WARNING);
+  diagnostic.option_index = opt;
+  ret = report_diagnostic (&diagnostic);
+  va_end (argp);
+  return ret;
+}
+
+
+/* Give a warning about the command-line.  */
+
+bool
 gfc_warning_cmdline (const char *gmsgid, ...)
 {
   va_list argp;
   diagnostic_info diagnostic;
+  bool ret;
 
   va_start (argp, gmsgid);
   diagnostic_set_info (&diagnostic, gmsgid, &argp, UNKNOWN_LOCATION,
 		       DK_WARNING);
+  ret = report_diagnostic (&diagnostic);
+  va_end (argp);
+  return ret;
+}
+
+
+/* Give an error about the command-line.  */
+
+void
+gfc_error_cmdline (const char *gmsgid, ...)
+{
+  va_list argp;
+  diagnostic_info diagnostic;
+
+  va_start (argp, gmsgid);
+  diagnostic_set_info (&diagnostic, gmsgid, &argp, UNKNOWN_LOCATION, DK_ERROR);
   report_diagnostic (&diagnostic);
   va_end (argp);
 }
 
 /* Clear the warning flag.  */
 
 void
 gfc_clear_warning (void)
 {
Index: gcc/fortran/lang.opt
===================================================================
--- gcc/fortran/lang.opt	(revision 215880)
+++ gcc/fortran/lang.opt	(working copy)
@@ -255,10 +255,14 @@  Warn about truncated source lines
 
 Wintrinsics-std
 Fortran Warning
 Warn on intrinsics not part of the selected standard
 
+Wmissing-include-dirs
+Fortran
+; Documented in C/C++
+
 Wuse-without-only
 Fortran Warning
 Warn about USE statements that have no ONLY qualifier
 
 Wopenmp-simd
Index: gcc/fortran/scanner.c
===================================================================
--- gcc/fortran/scanner.c	(revision 215880)
+++ gcc/fortran/scanner.c	(working copy)
@@ -322,23 +322,20 @@  add_path_to_list (gfc_directorylist **li
     q[i--] = '\0';
 
   if (stat (q, &st))
     {
       if (errno != ENOENT)
-	gfc_warning_now ("Include directory \"%s\": %s", path,
-			 xstrerror(errno));
-      else
-	{
-	  /* FIXME:  Also support -Wmissing-include-dirs.  */
-	  if (warn)
-	    gfc_warning_now ("Nonexistent include directory \"%s\"", path);
-	}
+	gfc_warning_cmdline ("Include directory %qs: %s", path,
+			     xstrerror(errno));
+      else if (warn)
+	gfc_warning_cmdline (OPT_Wmissing_include_dirs,
+			     "Nonexistent include directory %qs", path);
       return;
     }
   else if (!S_ISDIR (st.st_mode))
     {
-      gfc_warning_now ("\"%s\" is not a directory", path);
+      gfc_warning_cmdline ("%qs is not a directory", path);
       return;
     }
 
   if (head || *list == NULL)
     {
@@ -1923,11 +1920,11 @@  load_file (const char *realfilename, con
 	}
       else
 	input = gfc_open_file (realfilename);
       if (input == NULL)
 	{
-	  gfc_error_now ("Can't open file '%s'", filename);
+	  gfc_error_cmdline ("Can't open file %qs", filename);
 	  return false;
 	}
     }
   else
     {
Index: gcc/fortran/options.c
===================================================================
--- gcc/fortran/options.c	(revision 215880)
+++ gcc/fortran/options.c	(working copy)
@@ -170,10 +170,16 @@  gfc_init_options (unsigned int decoded_o
 			   | GFC_FPE_ZERO | GFC_FPE_OVERFLOW
 			   | GFC_FPE_UNDERFLOW;
   gfc_option.rtcheck = 0;
   gfc_option.coarray = GFC_FCOARRAY_NONE;
 
+  /* ??? Wmissing-include-dirs is disabled by default in C/C++ but
+     enabled by default in Fortran.  Ideally, we should express this
+     in .opt, but that is not supported yet.  */
+  if (!global_options_set.x_cpp_warn_missing_include_dirs)
+    global_options.x_cpp_warn_missing_include_dirs = 1;;
+
   set_default_std_flags ();
 
   /* Initialize cpp-related options.  */
   gfc_cpp_init_options (decoded_options_count, decoded_options);
   gfc_diagnostics_init ();
@@ -632,10 +638,12 @@  gfc_handle_option (size_t scode, const c
     return true;
 
   switch (code)
     {
     default:
+      if (cl_options[code].flags & gfc_option_lang_mask ())
+	break;
       result = false;
       break;
 
     case OPT_Wall:
       handle_generated_option (&global_options, &global_options_set,