[Bug libfortran/36857] New: Non-English locale breaks gfortran float formatting ("printf is broken")

["pav at iki dot fi" <gcc-bugzilla at gcc dot gnu dot org>]

GFortran float printing breaks when a non-English locale is selected. Instead,
"Internal error: printf is broken" appears. The failing part is a sanity check
in libgfortran, where it was forgotten that in some non-English locales,
sprintf will format floats using a comma instead of a period as the decimal
separator.

Tested gcc version 4:4.2.3-1ubuntu6 as bundled on Ubuntu Hardy, but probably
present also in trunk.

The following code triggers this bug:

bug.f90:
--------
program main
    CALL badlocale()
    WRITE(*,'(G2.4)') 1.2345
end program main

bug.c:
------
#include <locale.h>
void badlocale_() { setlocale(LC_ALL, "fi_FI.UTF-8"); }

The compiled program to fails with internal error:

    gcc -c -o bug.o bug.c; gfortran -o bug bug.f90 bug.o  -lc ; ./bug
    At line 3 of file bug.f90
    Internal Error: printf is broken

If the code executed correctly, the expected output would be

    1,235

To my understanding the failing code appears to be in
libgfortran/io/write_float.def:output_float (around line 126):

    /* Check the given string has punctuation in the correct places.  */
    if (d != 0 && (buffer[2] != '.' || buffer[ndigits + 2] != 'e'))
        internal_error (&dtp->common, "printf is broken");

Before execution arrives here, the buffer is filled by sprintf in write_float,
and as said, in some locales the correct formatting of a float will contain a
comma instead of a period.


-- 
           Summary: Non-English locale breaks gfortran float formatting
                    ("printf is broken")
           Product: gcc
           Version: 4.2.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libfortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pav at iki dot fi
 GCC build triplet: i486-linux-gnu
  GCC host triplet: i486-linux-gnu
GCC target triplet: i486-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36857