From jmitchell@frb.gov

This is a bug report for perl from jmitchell@​frb.gov,
generated with the help of perlbug 1.35 running under perl v5.8.8.

#!/opt/local/bin/perl

use strict;
use warnings;

# these do not become identical floating point numbers
my @​tests = (
  14151.155,
  1.4151155E4,
  );

for my $test (@​tests) {
  printf "%.30g\n", $test;
}

# this might be a false lead, but for some reason, they are identical
# after stringification
for my $test (@​tests) {
  printf "%.30g\n", $test . '';
}

# output on 5.8.8 and 5.10.0
# 14151.155000000001
# 14151.154999999999
# 14151.155000000001
# 14151.155000000001

# output on 5.8.5 (i.e. this problem hasn't always existed)​:
# 14151.155000000001
# 14151.155000000001
# 14151.155000000001
# 14151.155000000001

Flags​:
  category=core
  severity=medium

Site configuration information for perl v5.8.8​:

Configured by appadm at Mon Apr 27 10​:32​:55 EDT 2009.

Summary of my perl5 (revision 5 version 8 subversion 8) configuration​:
  Platform​:
  osname=linux, osvers=2.6.18-92.1.18.el5xen, archname=x86_64-linux-thread-multi
  uname='linux jhbdev.rsma.frb.gov 2.6.18-92.1.18.el5xen #1 smp wed nov 5 09​:15​:48 est 2008 x86_64 x86_64 x86_64 gnulinux '
  config_args='-des -Dprefix=/opt/perl -Duseshrplib -Dusethreads -Accflags=-DPERL_REENTRANT_MAXSIZE=65536'
  hint=recommended, useposix=true, d_sigaction=define
  usethreads=define use5005threads=undef useithreads=define usemultiplicity=define
  useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
  use64bitint=define use64bitall=define uselongdouble=undef
  usemymalloc=n, bincompat5005=undef
  Compiler​:
  cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DPERL_REENTRANT_MAXSIZE=65536 -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/local/include -I/opt/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
  optimize='-O2',
  cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DPERL_REENTRANT_MAXSIZE=65536 -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/local/include -I/opt/local/include -I/usr/include/gdbm'
  ccversion='', gccversion='4.1.2 20071124 (Red Hat 4.1.2-42)', gccosandvers=''
  intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
  d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
  ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
  alignbytes=8, prototype=define
  Linker and Libraries​:
  ld='cc', ldflags =' -L/usr/local/lib -L/opt/local/lib'
  libpth=/usr/local/lib /opt/local/lib /lib /usr/lib
  libs=-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -lc
  perllibs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
  libc=/lib/libc-2.5.so, so=so, useshrplib=true, libperl=libperl.so
  gnulibc_version='2.5'
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E -Wl,-rpath,/opt/perl/lib/5.8.8/x86_64-linux-thread-multi/CORE'
  cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib -L/opt/local/lib'

Locally applied patches​:
 

@​INC for perl v5.8.8​:
  /opt/perl/lib/5.8.8/x86_64-linux-thread-multi
  /opt/perl/lib/5.8.8
  /opt/perl/lib/site_perl/5.8.8/x86_64-linux-thread-multi
  /opt/perl/lib/site_perl/5.8.8
  /opt/perl/lib/site_perl
  .

Environment for perl v5.8.8​:
  HOME=/eim/home/m1jhm01
  LANG=en_US
  LANGUAGE (unset)
  LD_LIBRARY_PATH (unset)
  LOGDIR (unset)
  PATH=/eim/lib​:/opt/local/bin​:/usr/kerberos/bin​:/usr/local/bin​:/bin​:/usr/bin​:/usr/X11R6/bin
  PERL_BADLANG (unset)
  SHELL=/bin/tcsh

From zefram@fysh.org

Jeff Mitchell wrote​:

# these do not become identical floating point numbers
my @​tests = (
14151.155,
1.4151155E4,
);

This resembles [perl #41202]. We have a duff text->float conversion.

-zefram

The RT System itself - Status changed from 'new' to 'open'

From jmitchell@frb.gov

On Tue May 11 07​:46​:42 2010, zefram@​fysh.org wrote​:

This resembles [perl #41202]. We have a duff text->float conversion.

-zefram

I agree, and noticed that bug as well. However, it might be worth
noting that I could replicate the bug in 41202 on 5.8.5 whereas this bug
did not exist in 5.8.5.

From @jkeenan

On Tue May 11 08​:56​:15 2010, jhm713 wrote​:

On Tue May 11 07​:46​:42 2010, zefram@​fysh.org wrote​:

This resembles [perl #41202]. We have a duff text->float conversion.

-zefram

I agree, and noticed that bug as well. However, it might be worth
noting that I could replicate the bug in 41202 on 5.8.5 whereas this bug
did not exist in 5.8.5.

Persists in 5.16.0. See attached.

From @jkeenan

75016_float.pl

This is now fixed in blead. Presumably it is from the same fix as #8730