[Bug fortran/38839] BIND(C): Allow non-digit/underscore/alphabetic binding names

[Bug fortran/38839] BIND(C): Allow non-digit/underscore/alphabetic binding names

[fxcoudert at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38839

Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |fxcoudert at gcc dot gnu.org
           Assignee|unassigned at gcc dot gnu.org      |fxcoudert at gcc dot gnu.org

--- Comment #5 from Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> ---
Should be fixed at the same time as this patch here:
https://gcc.gnu.org/ml/fortran/2014-06/msg00090.html , which reworks the
parsing of binding labels. I intend to find what the consensus is on this
issue, incorporate it into the patch, and close this.

[Bug fortran/38839] BIND(C): Allow non-digit/underscore/alphabetic binding names

[fxcoudert at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38839

--- Comment #6 from Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> ---
Author: fxcoudert
Date: Sun Jun 29 14:14:16 2014
New Revision: 212123

URL: https://gcc.gnu.org/viewcvs?rev=212123&root=gcc&view=rev
Log:
    PR fortran/36275
    PR fortran/38839

    * decl.c (check_bind_name_identifier): New function.
    (gfc_match_bind_c): Match any constant expression as binding
    label.
    * match.c (gfc_match_name_C): Remove.

    * gfortran.dg/binding_label_tests_2.f03: Adjust error messages.
    * gfortran.dg/binding_label_tests_27.f90: New file.

Added:
    trunk/gcc/testsuite/gfortran.dg/binding_label_tests_27.f90
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/decl.c
    trunk/gcc/fortran/match.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gfortran.dg/binding_label_tests_2.f03

[Bug fortran/38839] BIND(C): Allow non-digit/underscore/alphabetic binding names

[fxcoudert at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38839

Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |4.10.0

--- Comment #7 from Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> ---
Fixed on trunk.

[Bug fortran/38839] New: BIND(C): Allow non-digit/underscore/alphabetic binding names

[burnus at gcc dot gnu dot org]

Motivated by
http://groups.google.com/group/comp.lang.fortran/browse_thread/thread/d977a668b0316119

Currently, BIND(C, NAME=binding-name)  checks for ISALPHA and "_". However, the
C standard allows more (from ISO/IEC 9899:1999(E) = C99, Section 6.4.2
Indentifiers):

identifier:
   identifier-nondigit
   identifier   identifier-nondigit
   identifier   digit

identifier-nondigit:
   nondigit
   universal-character-name  <<<<<<<<
   other implementation-defined characters  <<<<<<

nondigit: One of
   _ a b c (...) z A B C (...) Z

digit:
  0 1 (...) 9


Note the items marked by "<<<<<". I'm not sure whether the current restriction
makes any problem in practice, but I could imaging that there is a legitimated
use for it, though I could not find a good example.

Currently, it is abused to call STDCALL programs which get a "@<n>" appended to
the name where "<n>" is related to how much needs to be popped from the stack.
The proper solution is to support STDCALL (PR 34112); thus I don't think this
is a proper use.

Does it make sense to change the error into a warning? Or to allow certain
other characters?

 * * *

Seemingly $ is allowed by "gcc -c -std=c99 -Wall -pedantic":

void t$FAst(void)
{
}


-- 
           Summary: BIND(C): Allow non-digit/underscore/alphabetic binding
                    names
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: burnus at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38839

[Bug fortran/38839] BIND(C): Allow non-digit/underscore/alphabetic binding names

[burnus at gcc dot gnu dot org]

------- Comment #1 from burnus at gcc dot gnu dot org  2009-01-14 16:00 -------
And for the universal-character-name, the following compiles with Intel's icc

void \u01ac(void) {
}

and should be valid C99. ICC generates the identifier "_u01ac". Using "gcc
-fextended-identifiers"
it shows up in the .o file as (readelf -a):
     8: 0000000000000000     6 FUNC    GLOBAL DEFAULT    1 ^^F^354


In the Fortran 2003 standard one finds:

R509 language-binding-spec is BIND (C [, NAME = scalar-char-initialization-expr
])
C540 (R509) The scalar-char-initialization-expr shall be of default character
kind.

That makes it a bit difficult to use UCNs ... From Fortran 2008 (below R508):

"NOTE 5.5
The C International Standard provides a facility for creating C identifiers
whose characters are not restricted to the C basic character set. Such a C
identifier is referred to as a universal character name (6.4.3 of the C
International Standard). The name of such a C identifier might include
characters that are not part of the representation method used by the processor
for default character. If so, the C entity cannot be referenced from Fortran."

Thus currently we only need to worry about '$' and maybe some others.
Optionally supporting non-default character strings and thus UCN might be done
later on (cf. also PR 38838 comment 3).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38839

[Bug fortran/38839] BIND(C): Allow non-digit/underscore/alphabetic binding names

[burnus at gcc dot gnu dot org]

------- Comment #2 from burnus at gcc dot gnu dot org  2009-01-14 16:09 -------
For UCN see also PR 9449.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38839

[Bug fortran/38839] BIND(C): Allow non-digit/underscore/alphabetic binding names

[fxcoudert at gcc dot gnu dot org]

-- 

fxcoudert 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         |2009-03-29 08:46:40
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38839

[Bug fortran/38839] BIND(C): Allow non-digit/underscore/alphabetic binding names

[dfranke at gcc dot gnu dot org]

------- Comment #3 from dfranke at gcc dot gnu dot org  2009-12-10 19:11 -------
See PR36275 for more possibilities on binding labels.


-- 

dfranke at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dfranke at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38839

[Bug fortran/38839] BIND(C): Allow non-digit/underscore/alphabetic binding names

[burnus at gcc dot gnu dot org]

------- Comment #4 from burnus at gcc dot gnu dot org  2009-12-10 19:52 -------
For "$" one should check whether it is allowed for the given target, cf.
DOLLARS_IN_IDENTIFIERS (-> gcc/c-opts.c and dollars_in_ident in libcpp/).

For UCN (universal-character name), the ASCII characters $, @ and ` are
allowed. Cf. C99 6.4.3 and libcpp _cpp_valid_ucn.

One could also think of supporting UCN with character kind=4 (cf. PR36275 and
PR 9449) - at least when -fextended-identifiers is specified - as vendor
extension. As gfortran uses libcpp and and has full support of wide chars, it
should not be difficult (but shall produce an error with -std=f2008).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38839