Re: ltdl and C++

[Alessandro Candini]

On 20/09/11 16:31, Patrick Welche wrote:
> On Mon, Sep 19, 2011 at 03:34:22PM +0200, Alessandro Candini wrote:
> > Hi everyone.
> > I have a problem making ltdl library work with some C++ code.
> > I have implemented my personal version of the example at the end of
> > Chapter 7 in the book "Autotools" by John Calcote.
> > Basically it is the same, but I have C++ source files and I use g++
> > instead of gcc.
> > Configure and make works but I do not produce a dynamic linked
> > executable, unlike the original John's example:
> > ../src $ ldd hello
> >      not a dynamic executable
> >
> > And I noticed that during compilation the fPIC flag is used although
> > I removed every reference to it in all my Makefile.am files.
> You are using libtool which works out sensible flags, and fPIC may be
> such a flag, so it doesn't need to appear in your Makefile.am.
>
> Maybe you could send us the output of "libtool --config" ?
>
> Cheers,
>
> Patrick
Ok, here you are some info about my environment and example project.

I'm building this project on this machine:
Linux office-007 2.6.38-11-generic #50-Ubuntu SMP Mon Sep 12 21:17:25 
UTC 2011 x86_64 x86_64 x86_64 GNU/Linux

This is my project structure:

hello_chap7/
|-- common
|   |-- hellocommon.h
|   |-- Makefile.am
|   `-- print.cpp
|-- configure.ac
|-- include
|   |-- libhello.h
|   `-- Makefile.am
|-- libhello
|   |-- hello_print.cpp
|   `-- Makefile.am
|-- Makefile.am
`-- src
    |-- hello.cpp
    |-- Makefile.am
    |-- module.h
    `-- modules
        `-- hithere
            |-- hithere.cpp
            `-- Makefile.am

These are my Makefile.am files inside the project:

hello_chap7/libhello/Makefile.am:

lib_LTLIBRARIES = libhello.la
libhello_la_SOURCES = hello_print.cpp
libhello_la_CPPFLAGS = -I$(top_srcdir)/include -I$(top_srcdir)/common
libhello_la_LIBADD = ../common/libhellocommon.la
#-----------------------------------------------------------------------

hello_chap7/src/modules/hithere/Makefile.am:

pkglib_LTLIBRARIES = hithere.la
hithere_la_SOURCES = hithere.cpp
hithere_la_LDFLAGS = -module -avoid-version
#-----------------------------------------------------------------------

hello_chap7/src/Makefile.am:

SUBDIRS = modules/hithere

bin_PROGRAMS = hello
hello_SOURCES = hello.cpp module.h
hello_CPPFLAGS = -I$(top_srcdir)/include
hello_LDADD = ../libhello/libhello.la -dlopen modules/hithere/hithere.la

check_SCRIPTS = greptest.sh
TESTS = $(check_SCRIPTS)

greptest.sh:
    echo './hello | grep "Caneta says .* using program .*hello!"' > 
greptest.sh
    chmod +x greptest.sh

CLEANFILES = greptest.sh
#-----------------------------------------------------------------------

hello_chap7/include/Makefile.am:

include_HEADERS = libhello.h
#-----------------------------------------------------------------------

hello_chap7/common/Makefile.am:

noinst_LTLIBRARIES = libhellocommon.la
libhellocommon_la_SOURCES = hellocommon.h print.cpp
#-----------------------------------------------------------------------

hello_chap7/Makefile.am:

SUBDIRS = common include libhello src
#-----------------------------------------------------------------------

And in the end the libtool --config output:

macro_version=2.2.6b
macro_revision=1.3017
AS=as
DLLTOOL=dlltool
OBJDUMP=objdump
build_libtool_libs=yes
build_old_libs=yes
pic_mode=default
fast_install=yes
host_alias=
host=x86_64-pc-linux-gnu
host_os=linux-gnu
build_alias=x86_64-linux-gnu
build=x86_64-pc-linux-gnu
build_os=linux-gnu
SED="/bin/sed"
Xsed="$SED -e 1s/^X//"
GREP="/bin/grep"
EGREP="/bin/grep -E"
FGREP="/bin/grep -F"
NM="/usr/bin/nm -B"
LN_S="ln -s"
max_cmd_len=3458764513820540925
objext=o
exeext=
lt_unset=unset
SP2NL="tr \\040 \\012"
NL2SP="tr \\015\\012 \\040\\040"
reload_flag=" -r"
reload_cmds="\$LD\$reload_flag -o \$output\$reload_objs"
deplibs_check_method="pass_all"
file_magic_cmd="\$MAGIC_CMD"
AR="ar"
AR_FLAGS="cru"
STRIP="strip"
RANLIB="ranlib"
old_postinstall_cmds="chmod 644 \$oldlib~\$RANLIB \$oldlib"
old_postuninstall_cmds=""
LTCC="gcc"
LTCFLAGS="-Wall -g -O2"
global_symbol_pipe="sed -n -e 's/^.*[    
 ]\\([ABCDGIRSTW][ABCDGIRSTW]*\\)[     ][    
 ]*\\([_A-Za-z][_A-Za-z0-9]*\\)\$/\\1 \\2 \\2/p'"
global_symbol_to_cdecl="sed -n -e 's/^T .* \\(.*\\)\$/extern int 
\\1();/p' -e 's/^[ABCDGIRSTW]* .* \\(.*\\)\$/extern char \\1;/p'"
global_symbol_to_c_name_address="sed -n -e 's/^: \\([^ ]*\\) \$/  
{\\\"\\1\\\", (void *) 0},/p' -e 's/^[ABCDGIRSTW]* \\([^ ]*\\) \\([^ 
]*\\)\$/  {\"\\2\", (void *) \\&\\2},/p'"
global_symbol_to_c_name_address_lib_prefix="sed -n -e 's/^: \\([^ ]*\\) 
\$/  {\\\"\\1\\\", (void *) 0},/p' -e 's/^[ABCDGIRSTW]* \\([^ ]*\\) 
\\(lib[^ ]*\\)\$/  {\"\\2\", (void *) \\&\\2},/p' -e 's/^[ABCDGIRSTW]* 
\\([^ ]*\\) \\([^ ]*\\)\$/  {\"lib\\2\", (void *) \\&\\2},/p'"
objdir=.libs
SHELL="/bin/bash"
ECHO="echo"
MAGIC_CMD=file
need_locks="no"
DSYMUTIL=""
NMEDIT=""
LIPO=""
OTOOL=""
OTOOL64=""
libext=a
shrext_cmds=".so"
extract_expsyms_cmds=""
variables_saved_for_relink="PATH LD_LIBRARY_PATH LD_RUN_PATH 
GCC_EXEC_PREFIX COMPILER_PATH LIBRARY_PATH"
need_lib_prefix=no
need_version=no
version_type=linux
runpath_var=LD_RUN_PATH
shlibpath_var=LD_LIBRARY_PATH
shlibpath_overrides_runpath=no
libname_spec="lib\$name"
library_names_spec="\${libname}\${release}\${shared_ext}\$versuffix 
\${libname}\${release}\${shared_ext}\$major \$libname\${shared_ext}"
soname_spec="\${libname}\${release}\${shared_ext}\$major"
postinstall_cmds=""
postuninstall_cmds=""
finish_cmds="PATH=\\\"\\\$PATH:/sbin\\\" ldconfig -n \$libdir"
finish_eval=""
hardcode_into_libs=yes
sys_lib_search_path_spec="/lib/ /usr/lib/ /usr/X11R6/lib/ /usr/local/lib/"
sys_lib_dlsearch_path_spec="/lib /usr/lib /usr/local/lib 
/lib/x86_64-linux-gnu /usr/lib/x86_64-linux-gnu "
dlopen_support=yes
dlopen_self=yes
dlopen_self_static=no
old_striplib="strip --strip-debug"
striplib="strip --strip-unneeded"
LD="/usr/bin/ld -m elf_x86_64"
old_archive_cmds="\$AR \$AR_FLAGS \$oldlib\$oldobjs~\$RANLIB \$oldlib"
CC="gcc"
with_gcc=yes
no_builtin_flag=" -fno-builtin"
wl="-Wl,"
pic_flag=" -fPIC -DPIC"
link_static_flag="-static"
compiler_c_o="yes"
build_libtool_need_lc=no
allow_libtool_libs_with_static_runtimes=no
export_dynamic_flag_spec="\${wl}--export-dynamic"
whole_archive_flag_spec="\${wl}--whole-archive\$convenience 
\${wl}--no-whole-archive"
compiler_needs_object="no"
old_archive_from_new_cmds=""
old_archive_from_expsyms_cmds=""
archive_cmds="\$CC -shared \$libobjs \$deplibs \$compiler_flags 
\${wl}-soname \$wl\$soname -o \$lib"
archive_expsym_cmds="echo \\\"{ global:\\\" > \$output_objdir/\$libname.ver~
        cat \$export_symbols | sed -e \\\"s/\\\\(.*\\\\)/\\\\1;/\\\" >> 
\$output_objdir/\$libname.ver~
        echo \\\"local: *; };\\\" >> \$output_objdir/\$libname.ver~
        \$CC -shared \$libobjs \$deplibs \$compiler_flags \${wl}-soname 
\$wl\$soname \${wl}-version-script \${wl}\$output_objdir/\$libname.ver 
-o \$lib"
module_cmds=""
module_expsym_cmds=""
with_gnu_ld="yes"
allow_undefined_flag=""
no_undefined_flag=""
hardcode_libdir_flag_spec="\${wl}-rpath \${wl}\$libdir"
hardcode_libdir_flag_spec_ld=""
hardcode_libdir_separator=""
hardcode_direct=no
hardcode_direct_absolute=no
hardcode_minus_L=no
hardcode_shlibpath_var=unsupported
hardcode_automatic=no
inherit_rpath=no
link_all_deplibs=no
fix_srcfile_path=""
always_export_symbols=no
export_symbols_cmds="\$NM \$libobjs \$convenience | \$global_symbol_pipe 
| \$SED 's/.* //' | sort | uniq > \$export_symbols"
exclude_expsyms="_GLOBAL_OFFSET_TABLE_|_GLOBAL__F[ID]_.*"
include_expsyms=""
prelink_cmds=""
file_list_spec=""
hardcode_action=immediate
compiler_lib_search_dirs=""
predep_objects=""
postdep_objects=""
predeps=""
postdeps=""
compiler_lib_search_path=""

--
Alessandro Candini

MEEO S.r.l.
Via Saragat 9
I-44122 Ferrara, Italy
Tel: +39 0532 1861501
Fax: +39 0532 1861637
http://www.meeo.it

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