https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79540
--- Comment #16 from John David Anglin <danglin at gcc dot gnu.org> --- print '(f2.1)', 100.000000 end Here is backtrace info: Breakpoint 2, 0x7afce720 in memcpy () from /usr/lib/libc.2 (gdb) p/x $r26 $6 = 0x7eff0c1d (gdb) p/x $r25 $8 = 0x7eff0d9a (gdb) p/x $r24 $5 = 0xfffffffd $r24 contains number of bytes to copy. (gdb) bt Python Exception <type 'exceptions.ImportError'> Failed to load /home/gnu/lib/python2.7/lib-dynload/itertools.sl: #0 0x7afce720 in memcpy () from /usr/lib/libc.2 #1 0x7adcb884 in build_float_string (dtp=0x7eff0658, f=0x0, buffer=0x7eff0d98 '+100.\000', size=1, nprinted=0, precision=1, sign_bit=0, zero_flag=0, npad=0, result=0x7eff0c18 ' .\377\006\364\000', len=0x7eff0f18) at ../../../gcc/libgfortran/io/write_float.def:630 #2 0x7adcc00c in get_float_string (dtp=0xfffffffd, f=0x7eff0658, source=0xfffffffd <error: Cannot access memory at address 0xfffffffd>, kind=2130644378, comp_d=0, buffer=0x7eff0d98 '+100.\000', precision=1, size=6, result=0x7eff0c18 ' .\377\006\364\000', res_len=0x7eff0f18) at ../../../gcc/libgfortran/io/write_float.def:1065 #3 0x7adcd4dc in write_float_0 (dtp=0xfffffffd, f=0x7eff0c1d, source=0x7eff0c1c '.\377\006\364\000', kind=2130644378) at ../../../gcc/libgfortran/io/write.c:1584 #4 0x7adc1420 in formatted_transfer_scalar_write (dtp=0xfffffffd, type=2130643997, p=0x7eff0658, kind=28, size=4) at ../../../gcc/libgfortran/io/transfer.c:2097 #5 0x7adc1984 in formatted_transfer (dtp=0x7eff0658, type=BT_UNKNOWN, p=0xfffffffd, kind=2130643996, size=4, nelems=1) at ../../../gcc/libgfortran/io/transfer.c:2335 #6 0x7adbd0a4 in wrap_scalar_transfer.constprop.0 (dtp=0x7eff0c1d, type=2130644378, p=0xfffffffd, kind=1074790400, size=4) at ../../../gcc/libgfortran/io/transfer.c:2369 #7 0x7adbd6c8 in *_gfortran_transfer_real (dtp=0xfffffffd, p=0x7eff0c1d, kind=2130644378) at ../../../gcc/libgfortran/io/transfer.c:2396 #8 0x7adbd728 in *_gfortran_transfer_real_write (dtp=0x7eff0c1d, p=0x7eff0d9a, kind=-3) at ../../../gcc/libgfortran/io/transfer.c:2402 write_float.def may be miscompiled.