[Bug libfortran/47434] New: Wrong field width for NaN with (F0.n) formatting

[thenlich at users dot sourceforge.net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47434

           Summary: Wrong field width for NaN with (F0.n) formatting
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libfortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: thenlich@users.sourceforge.net


When formatting NaN with a F edit descriptor where the field width is zero, the
string "<blank>NaN" is written (field width = 4).

The expected string would be "NaN" (field width = 3, the smallest positive
actual field width that does not result in a field filled with asterisks).

For example: 

program testnan
    real :: n = 0.0
    n = 0.0 / n
    print "(F0.2)", n
    print "(F3.2)", n
end program testnan

Output:
<blank>NaN
NaN

10.7.2.1
(6) On output, with I, B, O, Z, F, and G editing, the specified value of the
field width w may be zero. In such cases, the processor selects the smallest
positive actual field width that does not result in a field filled with
asterisks. The specified value of w shall not be zero on input.

10.7.2.3.2 F editing
For an internal value that is an IEEE NaN, the output field consists of blanks,
if necessary, followed by the letters 'NaN' and optionally followed by one to w
- 5 alphanumeric processor-dependent characters enclosed in parentheses, right
justified within the field. If w is less than 3, the field is filled with
asterisks.