[Bug fortran/39229] New: fixed-form: silent line truncation in procedure calls

[Bug fortran/39229] New: fixed-form: silent line truncation in procedure calls

[dfranke at gcc dot gnu dot org]

If 'warn' after PRINT is removed, the snippet is accepted as is, without
further warning. I'm not sure if this kind of thing is legal to begin with, but
I'd at least expect a warning for both truncated lines.

$> cat trunc.f
      PRINT *, MIN(1                                                     nowarn
     &, 2)                               !                               warn
      END
$> gfortran-svn -ffixed-form -Wall -Wextra  trunc.f
trunc.f:2.72:

     &, 2)
                                                                        1
Warning: Line truncated at (1)

$> gfortran-svn -v
gcc version 4.4.0 20090217 (experimental) (GCC)


-- 
           Summary: fixed-form: silent line truncation in procedure calls
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dfranke at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39229

[Bug fortran/39229] No warning of truncated lines if a continuation line follows

[burnus at gcc dot gnu dot org]

------- Comment #1 from burnus at gcc dot gnu dot org  2009-02-18 10:20 -------
I think that also happens if one does not have a procedure call but simply have
a succeeding continuation line, e.g.:
      print *, min(1,2)       [...]  some long line
     & , 2

And it seems to happen also with free-form code which has warning enabled by
default.


-- 

burnus at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |burnus at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-02-18 10:20:31
               date|                            |
            Summary|fixed-form: silent line     |No warning of truncated
                   |truncation in procedure     |lines if a continuation line
                   |calls                       |follows


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39229

[Bug fortran/39229] No warning of truncated lines if a continuation line follows

[burnus at gcc dot gnu dot org]

------- Comment #2 from burnus at gcc dot gnu dot org  2009-02-18 16:41 -------
> I'm not sure if this kind of thing is legal to begin with

Well, the Fortran standard only has:

Free form: "If a line consists entirely of characters of default kind (4.4.4),
it may contain at most 132 characters. If a line contains any character that is
not of default kind, the maximum number of characters allowed on the line is
processor dependent." [3.3.1]

Fixed form: "If a source line contains only default kind characters, it shall
contain exactly 72 characters; otherwise, its maximum number of characters is
processor dependent."

Thus a conforming program may not have more than 72/132 characters in a line
(incl. comments) and this is no issue. The standard does not write anything
about what the compiler has to do.

Common is that 73+ characters are ignored in fixed form and thus several people
used it to put comments there. Additionally, everyone assumes that longer lines
are OK as long as long as there is a "!" before 72/132. (-> all compilers I
know do so).

As free form indicates non-legacy code and as F90 has "!" comments, the
truncation trick wont work. Some compilers truncates, some give an error, some
a warning (and stop - or continue reading the line) and some simply read on.

gfortran does: Fixed form: Truncating + optional warning
               Free  form: Truncating + default-on warning
               optionally: Accept longer lines ("n" characters or "infinity")


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39229

[Bug fortran/39229] No warning of truncated lines if a continuation line follows

[dfranke at gcc dot gnu dot org]

------- Comment #3 from dfranke at gcc dot gnu dot org  2009-02-23 19:38 -------
parse.c (next_statement):
816   if (gfc_at_eol ())
817     {
818       if ((gfc_option.warn_line_truncation || gfc_current_form ==
FORM_FREE)
819           && gfc_current_locus.lb
820           && gfc_current_locus.lb->truncated)
821         gfc_warning_now ("Line truncated at %C");
822
823       gfc_advance_line ();
824     }

scanner.c:
gfc_at_eol (void)
{
  if (gfc_at_eof ())
    return 1;

  return (*gfc_current_locus.nextc == '\0');
}

in gdb:

Breakpoint 1, next_statement () at
/home/daniel/svn/gcc-whole-file/gcc/fortran/parse.c:816
816           if (gfc_at_eol ())
(gdb) print *gfc_current_locus->lb
$22 = {location = 3, file = 0xa8a4930, next = 0xa8bb5f8, truncated = 1,
dbg_emitted = 0 '\0', line = {32}}
(gdb) print *gfc_current_locus->nextc
$23 = 32
(gdb) cont
Continuing.

Breakpoint 1, next_statement () at
/home/daniel/svn/gcc-whole-file/gcc/fortran/parse.c:816
816           if (gfc_at_eol ())
(gdb) print *gfc_current_locus->lb
$24 = {location = 131, file = 0xa8a4930, next = 0xa8bb738, truncated = 0,
dbg_emitted = 1 '\001', line = {32}}
(gdb) print *gfc_current_locus->nextc
$25 = 0

For the continued line gfc_at_eol() returns false and thus its truncated-flag
is silently lost.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39229

[Bug fortran/39229] No warning of truncated lines if a continuation line follows

[jvdelisle at gcc dot gnu dot org]

-- 

jvdelisle at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jvdelisle at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2009-02-18 10:20:31         |2009-03-08 18:05:25
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39229

[Bug fortran/39229] No warning of truncated lines if a continuation line follows

[jvdelisle at gcc dot gnu dot org]

------- Comment #4 from jvdelisle at gcc dot gnu dot org  2009-07-25 16:46 -------
There are two things going on here.  First, because of the continuation, the
scanner actually combines the two lines into one line.  Secondly, we have code
that deliberately clears the truncation flag because it was considered a
nuisance to warn on anything after a comment.


          /* Avoid truncation warnings for comment ending lines.  */
          gfc_current_locus.lb->truncated = 0;

I am inclined to leave this as is because it is a common practice to use
positions 73 thru 80 for indexing in legacy fixed form code. (Remember those
punch cards!)

Changing to won't fix.  If someone feels strongly about this otherwise, just
let me know.  It is not difficult to change.


-- 

jvdelisle at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |WONTFIX


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39229

[Bug fortran/39229] No warning of truncated lines if a continuation line follows

[burnus at gcc dot gnu dot org]

------- Comment #5 from burnus at gcc dot gnu dot org  2009-07-25 17:09 -------
(In reply to comment #4)
> I am inclined to leave this as is because it is a common practice to use
> positions 73 thru 80 for indexing in legacy fixed form code. (Remember those
> punch cards!)

Yes - and that's the reason why there is no warning by default. But it happens
very easily that one adds a space somewhere and all of a sudden the result
changes. How many lines does the following program print?
For that reason, gfortran offers an option to diagnose this. If one uses those
columns for comments, one does not need to enable the warning (off by default
for fixed-form code).


      ! Expected: No warning by default (as column 73+ is often used for
      ! comments in fixed-form source code.
      ! However, with -Wline-truncation there shall be a warning.
      implicit none
        call foo([11, 22, 33, 44, 55, 66, 770, 9900, 1100, 1100, 120], 12
     &          , 'Hello')
      contains
      subroutine foo(a,n,s)
        integer :: a(*), n, i
        character(len=*) :: s
        do i = 1, n
          print *, s, a(i)
        end do
      end subroutine foo
      end

! Answer: One line, the "12" gets truncated to "1". Such problems can easily
happens if one corrects e.g. a "99" to "100" - and the previous editor used all
space and put the comma in the next line.


-- 

burnus at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|WONTFIX                     |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39229

[Bug fortran/39229] No warning of truncated lines if a continuation line follows

[jvdelisle at gcc dot gnu dot org]

------- Comment #6 from jvdelisle at gcc dot gnu dot org  2009-09-01 03:02 -------
Subject: Bug 39229

Author: jvdelisle
Date: Tue Sep  1 03:02:07 2009
New Revision: 151258

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=151258
Log:
2009-08-31  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

        PR fortran/39229
        * scanner.c (next_char): Fix typo in comment.
        (gfc_get_char_literal): Warn if truncate flag is set for both fixed and
        free form source, adjusting error locus as needed.
        * parse.c (next_fixed): Clear the truncate flag.
        (next_statement): Remove truncate warning.

Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/parse.c
    trunk/gcc/fortran/scanner.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39229

[Bug fortran/39229] No warning of truncated lines if a continuation line follows

[jvdelisle at gcc dot gnu dot org]

------- Comment #7 from jvdelisle at gcc dot gnu dot org  2009-09-02 01:03 -------
Subject: Bug 39229

Author: jvdelisle
Date: Wed Sep  2 01:03:34 2009
New Revision: 151309

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=151309
Log:
2009-09-01  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

        PR fortran/39229
        * gfortran.dg/line_length_3.f: New test.
        * gfortran.dg/line_length_4.f90: New test.

Added:
    trunk/gcc/testsuite/gfortran.dg/line_length_3.f
    trunk/gcc/testsuite/gfortran.dg/line_length_4.f90
Modified:
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39229

[Bug fortran/39229] No warning of truncated lines if a continuation line follows

[jvdelisle at gcc dot gnu dot org]

------- Comment #8 from jvdelisle at gcc dot gnu dot org  2009-09-02 01:19 -------
Closing.


-- 

jvdelisle at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39229