re PR fortran/18537 (no warning about tabs with std=f95 option)

        PR 18537
        * gfortran.h: Wrap Copyright line.
        (gfc_option_t): add warn_tabs member.
        * lang.opt: Update Coyright year.  Add the Wtabs.
        * invoke.texi: Document -Wtabs.
        * scanner.c (gfc_gobble_whitespace): Use warn_tabs.  Add linenum to
        suppress multiple warnings.
        (load_line): Use warn_tabs.  Add linenum, current_line, seen_comment
        to suppress multiple warnings.
        * options.c (gfc_init_options): Initialize warn_tabs.
        (set_Wall): set warn_tabs for -Wall.
        (gfc_post_options): Adjust flag_tabs depending on -pedantic.
        (gfc_handle_option):  Process command-line option -W[no-]tabs

From-SVN: r112066

6 files changed, 83 insertions, 18 deletions

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index b5f7d73..47e6afd 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,19 @@
+2006-03-14  Steven G. Kargl  <kargls@comcast.net>
+
+	PR 18537
+	* gfortran.h: Wrap Copyright line.
+	(gfc_option_t): add warn_tabs member.
+	* lang.opt: Update Coyright year.  Add the Wtabs.
+	* invoke.texi: Document -Wtabs.
+	* scanner.c (gfc_gobble_whitespace): Use warn_tabs.  Add linenum to
+	suppress multiple warnings.
+	(load_line): Use warn_tabs.  Add linenum, current_line, seen_comment
+	to suppress multiple warnings.
+	* options.c (gfc_init_options): Initialize warn_tabs.
+	(set_Wall): set warn_tabs for -Wall.
+	(gfc_post_options): Adjust flag_tabs depending on -pedantic.
+	(gfc_handle_option):  Process command-line option -W[no-]tabs
+
 2006-03-13  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/25378
diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index 99b9865..0e6b21c 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -1,6 +1,6 @@
 /* gfortran header file
-   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software 
-   Foundation, Inc.
+   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006
+   Free Software Foundation, Inc.
    Contributed by Andy Vaught
 
 This file is part of GCC.
@@ -1605,8 +1605,9 @@ typedef struct
   int warn_conversion;
   int warn_implicit_interface;
   int warn_line_truncation;
-  int warn_underflow;
   int warn_surprising;
+  int warn_tabs;
+  int warn_underflow;
   int warn_unused_labels;
 
   int flag_default_double;
diff --git a/gcc/fortran/invoke.texi b/gcc/fortran/invoke.texi
index c031cd4..a65fbff 100644
--- a/gcc/fortran/invoke.texi
+++ b/gcc/fortran/invoke.texi
@@ -128,8 +128,8 @@ by type.  Explanations are in the following sections.
 @xref{Warning Options,,Options to Request or Suppress Warnings}.
 @gccoptlist{
 -fsyntax-only  -pedantic  -pedantic-errors @gol
--w  -Wall  -Waliasing  -Wconversion @gol
--Wimplicit-interface  -Wnonstd-intrinsics  -Wsurprising  -Wunderflow @gol
+-w  -Wall  -Waliasing  -Wconversion -Wimplicit-interface @gol
+-Wtabs -Wnonstd-intrinsics -Wsurprising -Wunderflow @gol
 -Wunused-labels -Wline-truncation -W}
 
 @item Debugging Options
@@ -378,8 +378,8 @@ Inhibit all warning messages.
 Enables commonly used warning options that which pertain to usage that
 we recommend avoiding and that we believe is easy to avoid.
 This currently includes @option{-Wunused-labels}, @option{-Waliasing},
-@option{-Wsurprising}, @option{-Wnonstd-intrinsic} and
-@option{-Wline-truncation}.
+@option{-Wsurprising}, @option{-Wnonstd-intrinsic},  @option{-Wno-tabs},
+and @option{-Wline-truncation}.
 
 
 @cindex -Waliasing option
@@ -445,6 +445,15 @@ lower value is greater than its upper value.
 A LOGICAL SELECT construct has three CASE statements.
 @end itemize
 
+@cindex -Wtabs
+@cindex options, -Wtabs
+@item -Wtabs
+@cindex Tabs
+By default, tabs are accepted as whitespace, but tabs are not members
+of the Fortran Character Set.  @option{-Wno-tabs} will cause a warning
+to be issued if a tab is encountered. Note, @option{-Wno-tabs} is active
+for @option{-pedantic}, @option{-std=f95}, and @option{-Wall}.
+
 @cindex -Wunderflow
 @cindex options, -Wunderflow
 @item -Wunderflow
diff --git a/gcc/fortran/lang.opt b/gcc/fortran/lang.opt
index 1752204..bbf5d81 100644
--- a/gcc/fortran/lang.opt
+++ b/gcc/fortran/lang.opt
@@ -1,5 +1,5 @@
 ; Options for the Fortran 95 front end.
-; Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
+; Copyright (C) 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
 ;
 ; This file is part of GCC.
 ;
@@ -61,6 +61,10 @@ Wsurprising
 Fortran
 Warn about \"suspicious\" constructs
 
+Wtabs
+Fortran
+Warn about nonconforming uses of the tab character
+
 Wunderflow
 Fortran
 Warn about underflow of numerical constant expressions
diff --git a/gcc/fortran/options.c b/gcc/fortran/options.c
index 6a9bec9..f0ab399 100644
--- a/gcc/fortran/options.c
+++ b/gcc/fortran/options.c
@@ -55,8 +55,9 @@ gfc_init_options (unsigned int argc ATTRIBUTE_UNUSED,
   gfc_option.warn_conversion = 0;
   gfc_option.warn_implicit_interface = 0;
   gfc_option.warn_line_truncation = 0;
-  gfc_option.warn_underflow = 1;
   gfc_option.warn_surprising = 0;
+  gfc_option.warn_tabs = 1;
+  gfc_option.warn_underflow = 1;
   gfc_option.warn_unused_labels = 0;
 
   gfc_option.flag_default_double = 0;
@@ -283,11 +284,12 @@ set_Wall (void)
 
   gfc_option.warn_aliasing = 1;
   gfc_option.warn_line_truncation = 1;
-  gfc_option.warn_underflow = 1;
+  gfc_option.warn_nonstd_intrinsics = 1;
   gfc_option.warn_surprising = 1;
+  gfc_option.warn_tabs = 0;
+  gfc_option.warn_underflow = 1;
   gfc_option.warn_unused_labels = 1;
-  gfc_option.warn_nonstd_intrinsics = 1;
-
+ 
   set_Wunused (1);
   warn_return_type = 1;
   warn_switch = 1;
@@ -395,14 +397,18 @@ gfc_handle_option (size_t scode, const char *arg, int value)
       gfc_option.warn_line_truncation = value;
       break;
 
-    case OPT_Wunderflow:
-      gfc_option.warn_underflow = value;
-      break;
-
     case OPT_Wsurprising:
       gfc_option.warn_surprising = value;
       break;
 
+    case OPT_Wtabs:
+      gfc_option.warn_tabs = value;
+      break;
+
+    case OPT_Wunderflow:
+      gfc_option.warn_underflow = value;
+      break;
+
     case OPT_Wunused_labels:
       gfc_option.warn_unused_labels = value;
       break;
@@ -547,6 +553,7 @@ gfc_handle_option (size_t scode, const char *arg, int value)
       gfc_option.allow_std = GFC_STD_F95_OBS | GFC_STD_F95 | GFC_STD_F77;
       gfc_option.warn_std = GFC_STD_F95_OBS;
       gfc_option.max_identifier_length = 31;
+      gfc_option.warn_tabs = 0;
       break;
 
     case OPT_std_f2003:
diff --git a/gcc/fortran/scanner.c b/gcc/fortran/scanner.c
index 2aadc1c..7c09b40 100644
--- a/gcc/fortran/scanner.c
+++ b/gcc/fortran/scanner.c
@@ -836,6 +836,7 @@ gfc_error_recovery (void)
 void
 gfc_gobble_whitespace (void)
 {
+  static int linenum = 0;
   locus old_loc;
   int c;
 
@@ -843,6 +844,15 @@ gfc_gobble_whitespace (void)
     {
       old_loc = gfc_current_locus;
       c = gfc_next_char_literal (0);
+      /* Issue a warning for nonconforming tabs.  We keep track of the line
+	 number because the Fortran matchers will often back up and the same
+	 line will be scanned multiple times.  */
+      if (!gfc_option.warn_tabs && c == '\t'
+	  && gfc_current_locus.lb->linenum != linenum)
+	{
+	  linenum = gfc_current_locus.lb->linenum;
+	  gfc_warning_now ("Nonconforming tab character at %C");
+	}
     }
   while (gfc_is_whitespace (c));
 
@@ -865,8 +875,9 @@ gfc_gobble_whitespace (void)
 static int
 load_line (FILE * input, char **pbuf, int *pbuflen)
 {
+  static int linenum = 0, current_line = 1;
   int c, maxlen, i, preprocessor_flag, buflen = *pbuflen;
-  int trunc_flag = 0;
+  int trunc_flag = 0, seen_comment = 0;
   char *buffer;
 
   /* Determine the maximum allowed line length.
@@ -932,8 +943,24 @@ load_line (FILE * input, char **pbuf, int *pbuflen)
 	  break;
 	}
 
+      /* Is this a fixed-form comment?  */
+      if (gfc_current_form == FORM_FIXED && i == 0
+	  && (c == '*' || c == 'c' || c == 'd'))
+	seen_comment = 1;
+
       if (gfc_current_form == FORM_FIXED && c == '\t' && i <= 6)
-	{			/* Tab expansion.  */
+	{
+	  /* The error machinery isn't available at this point, so we can't
+	     easily report line and column numbers consistent with other 
+	     parts of gfortran.  */
+	  if (!gfc_option.warn_tabs && seen_comment == 0
+	      && current_line != linenum)
+	    {
+	      linenum = current_line;
+	      gfc_warning_now (
+		"Nonconforming tab character in column 1 of line %d", linenum);
+	    }
+
 	  while (i <= 6)
 	    {
 	      *buffer++ = ' ';
@@ -985,6 +1012,7 @@ load_line (FILE * input, char **pbuf, int *pbuflen)
 
   *buffer = '\0';
   *pbuflen = buflen;
+  current_line++;
 
   return trunc_flag;
 }