proposal of change of Perl compile flags based on ExtUtils::Embed

[Patrice Dumas]

Hello,

The ExtUtils::Embed ccopts and ldopts are a kind of reference for
compile and link flags that should work when linking against Perl.
Based on the flags used/output by ExtUtils::Embed, I have some proposals
on changes for the flags we use for XS modules.

1) (Minor) I propose to add -I$(PERL_INC) directly in perl_conf_CFLAGS instead
   of adding it in tp/Texinfo/XS/Makefile.am

2) I propose to drop $PERL_CONF_optimize from perl_conf_CFLAGS since it
   is not set in ExtUtils::Embed ccopts.  It would avoid the frequent
   inconsistencies between PERL_EXT_CFLAGS and PERL_CONF_optimize.  It
   could lead to binary incompatibilities, but I doubt it since it is
   not in ExtUtils::Embed ccopts.

3) I propose to use ldflags in perl_conf_LDFLAGS.  It is described as
 This variable contains any additional C loader flags desired by the user. It 
is up to the Makefile to use this.
   Note that on Debian testing it leads to the addition of 
-fstack-protector-strong
   which could lead to spurious warning if combined with -O0 in
   PERL_EXT_CFLAGS, but I still think that it is better to add it.

4) I suggest adding perllibs to PERL_LIBS, which is only used on
   platforms needing -no-undefined.  It could be possible that it causes
   the link to fail as some libraries libperl is linked against are
   missing, but since it is in ExtUtils::Embed ldopts, it should be ok
   and maybe even needed for some platforms we have not encountered yet.
   It is described as
  The list of libraries needed by Perl only (any libraries needed by extensions 
only will by dropped, if using dynamic loading).

lddflags could also have been a good candidate (not in ExtUtils::Embed
flags because the ExtUtils::Embed target linking programs, not
libraries), but chances are that it duplicates the libtool flags.  Also,
it is UNKNOWN on a Debian testing, so I think that we should not use
that Config variable.


Any comment?


-- 
Pat