Getting Undefined Reference to Perl on C++ - c++

Question

Well, first of all, sorry about my bad english!
I'm new to linux, g++ and perl, and I'm getting some problems here.
I have a code in G++ which calls a perl .pl file to return a information. Right now, I'm just returning 1 or 0 from the perl .pl file for tests and to understand how does it works. But the problem is that I'm getting this from the $make:
sathlervbn Spam C # make clean;make
rm -f *.o
g++ -Wall -D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fstack-protector -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/lib/perl/5.14/CORE -c -o filedir.o filedir.cpp
g++ -Wall -D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fstack-protector -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/lib/perl/5.14/CORE -c -o main.o main.cpp
main.cpp: In function ‘int main(int, char**, char**)’:
main.cpp:112:41: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
main.cpp:112:41: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
g++ -L/usr/lib -Wall -Wl,-E -fstack-protector -L/usr/local/lib -L/usr/lib/perl/5.14/CORE - lperl -ldl -lm -lpthread -lc -lcrypt -o main filedir.o main.o
main.o: In function `getInfoPerl(std::string)':
main.cpp:(.text+0x1a): undefined reference to `Perl_push_scope'
main.cpp:(.text+0x33): undefined reference to `Perl_save_int'
main.cpp:(.text+0x73): undefined reference to `Perl_markstack_grow'
main.cpp:(.text+0xcd): undefined reference to `Perl_stack_grow'
main.cpp:(.text+0xfa): undefined reference to `Perl_newSVpv'
main.cpp:(.text+0x10d): undefined reference to `Perl_sv_2mortal'
main.cpp:(.text+0x13b): undefined reference to `Perl_call_pv'
main.cpp:(.text+0x18f): undefined reference to `Perl_sv_2iv_flags'
main.cpp:(.text+0x1bd): undefined reference to `Perl_free_tmps'
main.cpp:(.text+0x1ca): undefined reference to `Perl_pop_scope'
main.o: In function `main':
main.cpp:(.text+0x206): undefined reference to `Perl_sys_init3'
main.cpp:(.text+0x20b): undefined reference to `perl_alloc'
main.cpp:(.text+0x21d): undefined reference to `perl_construct'
main.cpp:(.text+0x265): undefined reference to `perl_parse'
main.cpp:(.text+0x272): undefined reference to `perl_run'
main.cpp:(.text+0x2fd): undefined reference to `perl_destruct'
main.cpp:(.text+0x30a): undefined reference to `perl_free'
main.cpp:(.text+0x30f): undefined reference to `Perl_sys_term'
collect2: error: ld returned 1 exit status
make: *** [main] Error 1
The main.cpp code is:
#include <EXTERN.h>
#include <perl.h>
#include <iostream>
#include <cstdio>
#include "filedir.h"
using namespace std;
PerlInterpreter *my_perl;
int getInfoPerl(string email){
dSP;
ENTER;
SAVETMPS;
PUSHMARK(SP);
XPUSHs(sv_2mortal(newSVpv(email.c_str(),0)));
PUTBACK;
call_pv("spamTeste", G_SCALAR);
SPAGAIN;
int resultado = POPi;
PUTBACK;
FREETMPS;
LEAVE;
return resultado;
}
int main(int argc, char **argv, char **env) {
char *my_argv[] = { " ", "spamPerl.pl" };
PERL_SYS_INIT3 (&argc, &argv, &env);
my_perl = perl_alloc();
perl_construct ( my_perl );
PL_exit_flags |= PERL_EXIT_DESTRUCT_END;
perl_parse(my_perl, NULL, 2, my_argv, (char **)NULL);
perl_run(my_perl);
cout << "Resultado " << getInfoPerl("email/email.txt") << endl;
perl_destruct(my_perl);
perl_free(my_perl);
PERL_SYS_TERM();
foobar bla bla bla another part from the code: doesn't matter.
}
Here is the makefile:
#CC= /usr/bin/g++
CPP = g++
CPPFLAGS = -Wall $(shell perl -MExtUtils::Embed -e ccopts)
#LD= /usr/bin/g++
LD = g++
LFLAGS = -Wall $(shell perl -MExtUtils::Embed -e ldopts)
#LFLAGS = -Wall -Wl,-E -fstack-protector -L/usr/local/lib -L/usr/lib/perl/5.14/CORE -lperl -ldl -lm -lpthread -lc -lcrypt
MAINOBJS = filedir.o main.o
EMAILS = main
EXECS = $(EMAILS)
#Regra Implicita:
.c.o:
$(CPP) $(CPPFLAGS) -c $<
all: emails
emails: $(EMAILS)
main: $(MAINOBJS)
$(LD) -L/usr/lib $(LFLAGS) -o $# $(MAINOBJS)
clean:
rm -f *.o
What I did? I've tried installing libperl-dev package, update the perl, and nothing solved.
I really need to fix this! Can someone help me?
UPDATE:
Changed the Header from main.cpp to:
#ifdef __cplusplus
extern "C" {
#endif
#include "EXTERN.h"
#include "perl.h"
#ifdef __cplusplus
}
#endif
#include <iostream>
#include <cstdio>
#include "filedir.h"
Didn't work...

Answer 1

The answer previous is right, it is cause by the sequence of gcc parameters. I test a sample code provided by the official perlembed tutorial:
http://perldoc.perl.org/perlembed.html
if the compile option is
cc -o interp interp.c perl -MExtUtils::Embed -e ccopts -e ldopts
as provided by the tutorial, it is right.
But any other sequence is wrong, for example:
cc interp.c -o interp perl -MExtUtils::Embed -e ccopts -e ldopts
cc perl -MExtUtils::Embed -e ccopts -e ldopts interp.c -o interp
so make sure in your Makefile -o goes the first and source file goes the second.

Answer 2

The problem was in the makefile:
#CC= /usr/bin/g++
CPP = g++
CPPFLAGS = -Wall $(shell perl -MExtUtils::Embed -e ccopts)
#LD= /usr/bin/g++
LD = g++
LFLAGS = -Wall $(shell perl -MExtUtils::Embed -e ldopts)
#LFLAGS = -Wall -Wl,-E -fstack-protector -L/usr/local/lib -L/usr/lib/perl/5.14/CORE -lperl -ldl -lm -lpthread -lc -lcrypt
MAINOBJS = filedir.o main.o
EMAILS = main
EXECS = $(EMAILS)
#Regra Implicita:
.c.o:
$(CPP) $(CPPFLAGS) -c $<
all: emails
emails: $(EMAILS)
main: $(MAINOBJS)
$(LD) -L/usr/lib $(LFLAGS) -o $# $(MAINOBJS)
clean:
rm -f *.o
As you can see, in this line, the code:
main: $(MAINOBJS)
$(LD) -L/usr/lib $(LFLAGS) -o $# $(MAINOBJS)
Should have the $(LFLAGS) after the $(MAINOBJS), so it should be:
main: $(MAINOBJS)
$(LD) -L/usr/lib -o $# $(MAINOBJS) $(LFLAGS)
Now, the linker is working perfectly. I'm sorry, but I can't say exactly why this is necessary, I've just discovered.