Fortran: Accept -std=f2023, update line-length for Fortran 2023

This patch accepts -std=f2023, uses it by default and bumps for the
free-source form the line length to 10,000 and the statement length
alias number of continuation lines to unlimited.

gcc/fortran/ChangeLog:

	* gfortran.texi (_gfortran_set_options): Document GFC_STD_F2023.
	* invoke.texi (std,pedantic,Wampersand,Wtabs): Add -std=2023.
	* lang.opt (std=f2023): Add.
	* libgfortran.h (GFC_STD_F2023, GFC_STD_OPT_F23): Add.
	* options.cc (set_default_std_flags): Add GFC_STD_F2023.
	(gfc_init_options): Set max_continue_free to 1,000,000.
	(gfc_post_options): Set flag_free_line_length if unset.
	(gfc_handle_option): Add OPT_std_f2023, set max_continue_free = 255
	for -std=f2003, f2008 and f2018.

gcc/testsuite/ChangeLog:

	* gfortran.dg/goacc/warn_truncated.f90: Add -std=f2018 option.
	* gfortran.dg/gomp/warn_truncated.f90: Likewise.
	* gfortran.dg/line_length_10.f90: Likewise.
	* gfortran.dg/line_length_11.f90: Likewise.
	* gfortran.dg/line_length_2.f90: Likewise.
	* gfortran.dg/line_length_5.f90: Likewise.
	* gfortran.dg/line_length_6.f90: Likewise.
	* gfortran.dg/line_length_7.f90: Likewise.
	* gfortran.dg/line_length_8.f90: Likewise.
	* gfortran.dg/line_length_9.f90: Likewise.
	* gfortran.dg/continuation_17.f90: New test.
	* gfortran.dg/continuation_18.f90: New test.
	* gfortran.dg/continuation_19.f: New test.
	* gfortran.dg/line_length_12.f90: New test.
	* gfortran.dg/line_length_13.f90: New test.

1 files changed, 25 insertions, 3 deletions

diff --git a/gcc/fortran/options.cc b/gcc/fortran/options.cc
index cfb1957..b788521 100644
--- a/gcc/fortran/options.cc
+++ b/gcc/fortran/options.cc
@@ -57,7 +57,7 @@ set_default_std_flags (void)
   gfc_option.allow_std = GFC_STD_F95_OBS | GFC_STD_F95_DEL
     | GFC_STD_F2003 | GFC_STD_F2008 | GFC_STD_F95 | GFC_STD_F77
     | GFC_STD_F2008_OBS | GFC_STD_GNU | GFC_STD_LEGACY
-    | GFC_STD_F2018 | GFC_STD_F2018_DEL | GFC_STD_F2018_OBS;
+    | GFC_STD_F2018 | GFC_STD_F2018_DEL | GFC_STD_F2018_OBS | GFC_STD_F2023;
   gfc_option.warn_std = GFC_STD_F2018_DEL | GFC_STD_F95_DEL | GFC_STD_LEGACY;
 }
 
@@ -143,8 +143,11 @@ gfc_init_options (unsigned int decoded_options_count,
   gfc_source_file = NULL;
   gfc_option.module_dir = NULL;
   gfc_option.source_form = FORM_UNKNOWN;
-  gfc_option.max_continue_fixed = 255;
-  gfc_option.max_continue_free = 255;
+  /* The following is not quite right as Fortran since 2023 has: "A statement
+      shall not have more than one million characters."  This can already be
+      reached by 'just' 100 lines with 10,000 characters each.  */
+  gfc_option.max_continue_fixed = 1000000;
+  gfc_option.max_continue_free = 1000000;
   gfc_option.max_identifier_length = GFC_MAX_SYMBOL_LEN;
   gfc_option.max_errors = 25;
 
@@ -266,6 +269,10 @@ gfc_post_options (const char **pfilename)
 		       cpp_warn_missing_include_dirs, 1);
   gfc_check_include_dirs (verbose_missing_dir_warn);
 
+  SET_OPTION_IF_UNSET (&global_options, &global_options_set,
+		       flag_free_line_length,
+		       (gfc_option.allow_std & GFC_STD_F2023) ? 10000 : 132);
+
   /* Finalize DEC flags.  */
   post_dec_flags (flag_dec);
 
@@ -769,6 +776,8 @@ gfc_handle_option (size_t scode, const char *arg, HOST_WIDE_INT value,
     case OPT_std_f2003:
       gfc_option.allow_std = GFC_STD_OPT_F03;
       gfc_option.warn_std = GFC_STD_F95_OBS;
+      gfc_option.max_continue_fixed = 255;
+      gfc_option.max_continue_free = 255;
       gfc_option.max_identifier_length = 63;
       warn_ampersand = 1;
       warn_tabs = 1;
@@ -777,6 +786,8 @@ gfc_handle_option (size_t scode, const char *arg, HOST_WIDE_INT value,
     case OPT_std_f2008:
       gfc_option.allow_std = GFC_STD_OPT_F08;
       gfc_option.warn_std = GFC_STD_F95_OBS | GFC_STD_F2008_OBS;
+      gfc_option.max_continue_free = 255;
+      gfc_option.max_continue_fixed = 255;
       gfc_option.max_identifier_length = 63;
       warn_ampersand = 1;
       warn_tabs = 1;
@@ -787,6 +798,17 @@ gfc_handle_option (size_t scode, const char *arg, HOST_WIDE_INT value,
       gfc_option.allow_std = GFC_STD_OPT_F18;
       gfc_option.warn_std = GFC_STD_F95_OBS | GFC_STD_F2008_OBS
 	| GFC_STD_F2018_OBS;
+      gfc_option.max_continue_free = 255;
+      gfc_option.max_continue_fixed = 255;
+      gfc_option.max_identifier_length = 63;
+      warn_ampersand = 1;
+      warn_tabs = 1;
+      break;
+
+    case OPT_std_f2023:
+      gfc_option.allow_std = GFC_STD_OPT_F23;
+      gfc_option.warn_std = GFC_STD_F95_OBS | GFC_STD_F2008_OBS
+	| GFC_STD_F2018_OBS;
       gfc_option.max_identifier_length = 63;
       warn_ampersand = 1;
       warn_tabs = 1;