[Bug libfortran/53051] New: I/O: Support reading floating-point numbers which use "Q" for the exponent

[Bug libfortran/53051] New: I/O: Support reading floating-point numbers which use "Q" for the exponent

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53051

             Bug #: 53051
           Summary: I/O: Support reading floating-point numbers which use
                    "Q" for the exponent
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libfortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: burnus@gcc.gnu.org
                CC: jvdelisle@gcc.gnu.org


gfortran supports since GCC 4.6 quadprecision on common hardware. Thus, users
started to expect that "q" works for the exponents, e.g., 4.0q0. (The "q" is a
vendor extension.)

In 4.7, the "q" became supported in the source code (with -Wreal-q-constant as
warning). Well, it seems as if we should to also support "q" in the library.

Cf. https://groups.google.com/forum/#!topic/comp.lang.fortran/rfDXj9VQRZM


Untested draft patch below.

--- a/libgfortran/io/list_read.c
+++ b/libgfortran/io/list_read.c
@@ -1138,2 +1138,4 @@ parse_real (st_parameter_dt *dtp, void *buffer, int
length)
        case 'D':
+       case 'q':
+       case 'Q':
          push_char (dtp, 'e');
@@ -1451,2 +1453,4 @@ read_real (st_parameter_dt *dtp, void * dest, int length)
        case 'd':
+       case 'Q':
+       case 'q':
          goto exp1;
@@ -1548,2 +1552,4 @@ read_real (st_parameter_dt *dtp, void * dest, int length)
        case 'd':
+       case 'Q'
+       case 'q':
          goto exp1;
diff --git a/libgfortran/io/read.c b/libgfortran/io/read.c
index aa41bc7..32c8b32 100644
--- a/libgfortran/io/read.c
+++ b/libgfortran/io/read.c
@@ -1028,2 +1028,4 @@ found_digit:
        case 'D':
+       case 'q':
+       case 'Q':
          ++p;

[Bug libfortran/53051] I/O: Support reading floating-point numbers which use "Q" for the exponent

[jb at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53051

Janne Blomqvist <jb at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2012-04-20
                 CC|                            |jb at gcc dot gnu.org
     Ever Confirmed|0                           |1

--- Comment #1 from Janne Blomqvist <jb at gcc dot gnu.org> 2012-04-20 08:21:05 UTC ---
The argument against supporting this, I suppose, is that we never generate a
"Q|q" exponent on output. 

As a result, the example in c.l.f doesn't try to parse something that was
previously written by formatting a floating point number, but rather a
hand-crafted string. IOW, it seems rather artificial.

That being said, it seems ifort supports it, so maybe we need to as well..
*sigh*.

[Bug libfortran/53051] I/O: Support reading floating-point numbers which use "Q" for the exponent

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53051

--- Comment #2 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-04-22 17:28:39 UTC ---
Author: burnus
Date: Sun Apr 22 17:28:34 2012
New Revision: 186675

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=186675
Log:
2012-04-22  Tobias Burnus  <burnus@net-b.de>

        PR fortran/53051
        * io/list_read.c (parse_real): Support "q" for the
        exponential.
        * io/read.c (read_f): Ditto.

2012-04-22  Tobias Burnus  <burnus@net-b.de>

        PR fortran/53051
        * gfortran.dg/read_float_4.f90: New.


Added:
    trunk/gcc/testsuite/gfortran.dg/read_float_4.f90
Modified:
    trunk/gcc/testsuite/ChangeLog
    trunk/libgfortran/ChangeLog
    trunk/libgfortran/io/list_read.c
    trunk/libgfortran/io/read.c

[Bug libfortran/53051] I/O: Support reading floating-point numbers which use "Q" for the exponent

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53051

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |burnus at gcc dot gnu.org
         Resolution|                            |FIXED

--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-04-22 17:30:02 UTC ---
FIXED on the 4.8 trunk.