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[perl #55896] h2xs does not handle properly enum constants

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From:
perlbug-followup
Date:
June 16, 2008 11:54
Subject:
[perl #55896] h2xs does not handle properly enum constants
Message ID:
rt-3.6.HEAD-21641-1213616799-209.55896-75-0@perl.org
# New Ticket Created by  domi@komarr.gre.hp.com 
# Please include the string:  [perl #55896]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=55896 >



This is a bug report for perl from domi@komarr.gre.hp.com,
generated with the help of perlbug 1.36 running under perl 5.10.0.


-----------------------------------------------------------------
[Please enter your report here]

Hello

I've used h2xs (hence ExtUtils::Constant) to generate bindings for
Augeas [1] library. Augeas header file includes constants defined with
enums:

enum aug_flags {
    AUG_NONE = 0,
    AUG_SAVE_BACKUP  = (1 << 0),  /* Keep the original file with a
                                     .augsave extension */
    AUG_SAVE_NEWFILE = (1 << 1),  /* Save changes into a file with
                                     extension .augnew, and do not
                                     overwrite the original file. Takes
                                     precedence over AUG_SAVE_BACKUP */
    AUG_TYPE_CHECK   = (1 << 2)   /* Typecheck lenses; since it can be very
                                     expensive it is not done by default */
};

h2xs correctly detects these constants, but it will generate a C code
that expects these constants to be #defined. See the generated
const-c.inc:
  case 8:
    if (memEQ(name, "AUG_NONE", 8)) {
#ifdef AUG_NONE
      *iv_return = AUG_NONE;
      return PERL_constant_ISIV;
#else
      return PERL_constant_NOTDEF;
#endif
    }
    break;

This code does not work as the constants are not known to cpp.

In itself, it not a big problem, but finding out what's wrong is a
pain when you're beginning  to learn XS :-/

There's a workaround suggested on Sun's blogs [2] which works fine.
(This blog also feature a fine explanation of the enum problem)

HTH

[1] http://augeas.net/
[2] http://blogs.sun.com/akolb/entry/pitfals_of_the_perl_xs

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=library
    severity=low
---
Site configuration information for perl 5.10.0:

Configured by Debian Project at Thu May  8 13:32:42 UTC 2008.

Summary of my perl5 (revision 5 version 10 subversion 0) configuration:
  Platform:
    osname=linux, osvers=2.6.24.4, archname=i486-linux-gnu-thread-multi
    uname='linux ninsei 2.6.24.4 #1 smp preempt fri apr 18 15:36:09 pdt 2008 i686 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=i486-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.10 -Darchlib=/usr/lib/perl/5.10 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.10.0 -Dsitearch=/usr/local/lib/perl/5.10.0 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib -Dlibperl=libperl.so.5.10.0 -Dd_dosuid -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -I/usr/local/include'
    ccversion='', gccversion='4.2.3 (Debian 4.2.3-5)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=4, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib /usr/lib64
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=/lib/libc-2.7.so, so=so, useshrplib=true, libperl=libperl.so.5.10.0
    gnulibc_version='2.7'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib'

Locally applied patches:
    

---
@INC for perl 5.10.0:
    /etc/perl
    /usr/local/lib/perl/5.10.0
    /usr/local/share/perl/5.10.0
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.10
    /usr/share/perl/5.10
    /usr/local/lib/site_perl
    .

---
Environment for perl 5.10.0:
    HOME=/home/domi
    LANG=en_US.UTF-8
    LANGUAGE=en_FR:en_US:en_GB:en
    LC_ALL=en_US.utf8
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/games:/opt/OC
    PERL_BADLANG (unset)
    SHELL=/bin/bash


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