[Bug fortran/30278] New: Inconsistencies with backslash handling

[Bug fortran/30278] New: Inconsistencies with backslash handling

[tobi at gcc dot gnu dot org]

A testcase provided by Eef van Beveren, notice the difference between the
handling of backslash in the format string and in the regular string:
schluter@pcl247d:~/src> cat backslash.f
      call wrt('\backslash')
      call wrt('\\backslash')
      write (*,100)
      write (*,200)
      stop
 100  format ('\backslash now results in \backslash')
 200  format ('\\backslash now results in \\backslash')
      end
      subroutine wrt(a)
      character*(*) a
      lena = len(a)
      write(*,*) 'results in: ', a(1:lena)
      return
      end

schluter@pcl247d:~/src> gfortran backslash.f
schluter@pcl247d:~/src> ./a.out
 results in:ackslash
 results in: \backslash
\backslash now results in \backslash
\\backslash now results in \\backslash
schluter@pcl247d:~/src> gfortran -fno-backslash backslash.f
schluter@pcl247d:~/src> ./a.out
 results in: \backslash
 results in: \\backslash
\backslash now results in \backslash
\\backslash now results in \\backslash
schluter@pcl247d:~/src> g77 backslash.f
schluter@pcl247d:~/src> ./a.out
 results in:ackslash
 results in: \backslash
ackslash now results inackslash
\backslash now results in \backslash
schluter@pcl247d:~/src>


-- 
           Summary: Inconsistencies with backslash handling
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: tobi at gcc dot gnu dot org
OtherBugsDependingO 19292
             nThis:


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30278

[Bug fortran/30278] Inconsistencies with backslash handling

[steven at gcc dot gnu dot org]

-- 

steven at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2006-12-23 12:12:23
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30278

[Bug fortran/30278] Inconsistencies with backslash handling

[steven at gcc dot gnu dot org]

------- Comment #1 from steven at gcc dot gnu dot org  2006-12-23 12:19 -------
This is what g77 outputs for this test case:
 results in:ackslash
 results in: \backslash
ackslash now results inackslash
\backslash now results in \backslash


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30278

[Bug fortran/30278] Inconsistencies with backslash handling

[steven at gcc dot gnu dot org]

------- Comment #2 from steven at gcc dot gnu dot org  2006-12-23 12:42 -------
I suspect that the problem is some difference between the front end and library
FORMAT parsers.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30278

[Bug fortran/30278] Inconsistencies with backslash handling

[steven at gcc dot gnu dot org]

------- Comment #3 from steven at gcc dot gnu dot org  2006-12-23 12:52 -------
This not-for-including patch shows that we should match "\\" in io.c and treat
it as a single '\\' character.  This is what g77 appears to do, too.

Index: io.c
===================================================================
--- io.c        (revision 120167)
+++ io.c        (working copy)
@@ -905,6 +905,24 @@ gfc_match_format (void)
   check_format ();             /* Guaranteed to succeed */
   gfc_match_eos ();            /* Guaranteed to succeed */

+  {
+    char c1, c2;
+    int i, j;
+    int len = e->value.character.length;
+    for (i = 0; i < len - 1; ++i)
+      {
+       c1 = e->value.character.string[i];
+       c2 = e->value.character.string[i + 1];
+       if (c1 == '\\' && c2 == '\\')
+         {
+           for (j = i; j < len; ++j)
+             e->value.character.string[j] = e->value.character.string[j+1];
+           len--;
+         }
+      }
+    e->value.character.length = len;
+  }
+
   return MATCH_YES;
 }


My understanding of io.c is not quite good, so perhaps someone who understands
that code well can have a look at a proper fix.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30278

[Bug fortran/30278] Inconsistencies with backslash handling

[tobi at gcc dot gnu dot org]

------- Comment #4 from tobi at gcc dot gnu dot org  2006-12-23 13:12 -------
NB The whole of \-ed symbols would have to be interpreted, conditionalized on
-fbackslash.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30278

[Bug fortran/30278] Inconsistencies with backslash handling

[steven at gcc dot gnu dot org]

------- Comment #5 from steven at gcc dot gnu dot org  2006-12-23 13:17 -------
Created an attachment (id=12838)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=12838&action=view)
Handle escaped characters if flag_backslash

Slightly less horrible patch...


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30278

[Bug fortran/30278] Inconsistencies with backslash handling

[jvdelisle at gcc dot gnu dot org]

------- Comment #6 from jvdelisle at gcc dot gnu dot org  2006-12-24 03:14 -------
With th patch in comment #5, NIST tests go OK.  It matches g77 behavior.

I am thinking though that the default behavior should be -fno-backslash.  With
-fno-backslash, gfortran matches intel behavior.  My impression is that
escaping with backslashes is non-standard behavior, so we should require a
parameter to invoke it.  It could also be tied in with -std=legacy.

If not this, then we should at least do -fno-backslash with -std=f95


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30278

[Bug fortran/30278] Inconsistencies with backslash handling

[kargl at gcc dot gnu dot org]

------- Comment #7 from kargl at gcc dot gnu dot org  2007-01-27 17:14 -------
Subject: Bug 30278

Author: kargl
Date: Sat Jan 27 17:14:06 2007
New Revision: 121234

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=121234
Log:
2007-01-26  Steven G. Kargl  <kargl@gcc.gnu.org>

        PR fortran/30278
        * gfortran.dg/backslash_3.f: New test.

2007-01-26  Steven Bosscher  <stevenb.gcc@gmail.com>
            Steven G. Kargl <kargl@gcc.gnu.org>

        PR fortran/30278
        * fortran/io.c (next_char): Deal with backslash escaped characters.
        Issue warnings in non -std=gnu cases.
        * fortran/primary.c (next_string_char): Issue warnings in non


Added:
    branches/gcc-4_1-branch/gcc/testsuite/gfortran.dg/backslash_3.f
Modified:
    branches/gcc-4_1-branch/gcc/fortran/ChangeLog
    branches/gcc-4_1-branch/gcc/fortran/io.c
    branches/gcc-4_1-branch/gcc/fortran/primary.c
    branches/gcc-4_1-branch/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30278

[Bug fortran/30278] Inconsistencies with backslash handling

[kargl at gcc dot gnu dot org]

------- Comment #8 from kargl at gcc dot gnu dot org  2007-01-27 17:16 -------
Fixed in 4.1, 4.2, and trunk.


-- 

kargl at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30278