(Taken from Accelerated C++)
Why does the following code not work:
#include <iostream>
#include <string>
int main() {
{
const std::string s = "a string";
std::cout << s << std::endl;
{
const std::string s = "another string";
std::cout << s << std::endl;
}
}
}
Am I not allowed to nest anonymous blocks in C++? When trying to compile the source, gcc gives me the following error (which I can't make any sense of):
hello: In function `_start':
(.text+0x0): multiple definition of
`_start'
/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crt1.o:(.text+0x0):
first defined here
hello:(.rodata+0x0): multiple
definition of `_fp_hw'
/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crt1.o:(.rodata+0x0):
first defined here hello: In function
`_fini': (.fini+0x0): multiple
definition of `_fini'
/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crti.o:(.fini+0x0):
first defined here
hello:(.rodata+0x4): multiple
definition of `_IO_stdin_used'
/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crt1.o:(.rodata.cst4+0x0):
first defined here hello: In function
`__data_start': (.data+0x0): multiple
definition of `__data_start'
/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crt1.o:(.data+0x0):
first defined here hello: In function
`__data_start': (.data+0x4): multiple
definition of `__dso_handle'
/usr/lib/gcc/i486-linux-gnu/4.4.3/crtbegin.o:(.data+0x0):
first defined here hello: In function
`_init': (.init+0x0): multiple
definition of `_init'
/usr/lib/gcc/i486-linux-gnu/4.4.3/../../../../lib/crti.o:(.init+0x0):
first defined here /tmp/cchh83A6.o: In
function `main':
hello.cpp:(.text+0x0): multiple
definition of `main'
hello:(.text+0xb4): first defined here
/usr/lib/gcc/i486-linux-gnu/4.4.3/crtend.o:(.dtors+0x0):
multiple definition of `__DTOR_END__'
hello:(.dtors+0x4): first defined here
/usr/bin/ld: warning: Cannot create
.eh_frame_hdr section, --eh-frame-hdr
ignored. /usr/bin/ld: error in
hello(.eh_frame); no .eh_frame_hdr
table will be created. collect2: ld
returned 1 exit status
That code works fine. See here Your code compiled (You have a problem with your environment)
You appear to be linking against 2, or more, object files (or .a files) that define the same things. If you link against one or the other your linker problem will go away.
Related
Simply including the OpenCV header results in linking error. Why is that?
// test.cpp
#include <opencv2/opencv.hpp>
int foo();
int bar();
int main() {
}
If I compile the file with g++ test.cpp, the following linking error occurs:
/tmp/ccugmQl4.o: In function `cv::String::~String()':
test.cpp:(.text._ZN2cv6StringD2Ev[_ZN2cv6StringD5Ev]+0x14): undefined reference to `cv::String::deallocate()'
/tmp/ccugmQl4.o: In function `cv::String::operator=(cv::String const&)':
test.cpp:(.text._ZN2cv6StringaSERKS0_[_ZN2cv6StringaSERKS0_]+0x28): undefined reference to `cv::String::deallocate()'
collect2: error: ld returned 1 exit status
If I compile with g++ test.cpp -lopencv_core, it works all right.
My question is:
It seems to me that there's no need to resolve undefined symbols if I do not use it, like the functions foo and bar. There's no definition for them but the compile-link process works alright.
I don't use any OpenCV functions either. Why is there linking error only for OpenCV functions?
And what kinds of stuff defined in headers can cause such a linking error?
If you tweak your example a little bit
// test.cpp
int foo();
int bar() {
foo();
}
int main() {
}
You would notice that it'd stop working because linker won't be able to understand what is foo();
The same thing happens when you include opencv header - there are references to functions which are declared but since you never link opencv itself - linker can't figure what those functions are and where to get them.
I wrote this simple program in cygwin:
#include <iostream>
int main()
{
int a;
float b;
std::cout << "Podaj liczbe calkowita: ";
std::cin >> a;
std::cout << "Podaj liczbe rzeczywista: ";
std::cin >> b;
std::cout << "Liczba a = " << a << std::endl;
std::cout << "Liczba b = " << b << std::endl;
return 0;
}
When I try to debug it with gdb, (compiling with -g option), and I get this as my output:
g++ -o -g test test.cpp
test: In function `mainCRTStartup':
/usr/src/debug/cygwin-2.4.1-1/winsup/cygwin/crt0.c:23: multiple definition of `mainCRTStartup'
/usr/lib/gcc/x86_64-pc-cygwin/4.9.3/../../../../lib/crt0.o:/usr/src/debug/cygwin-2.4.1-1/winsup/cygwin/crt0.c:23: first defined here
test: In function `mainCRTStartup':
/usr/src/debug/cygwin-2.4.1-1/winsup/cygwin/crt0.c:23: multiple definition of `WinMainCRTStartup'
/usr/lib/gcc/x86_64-pc-cygwin/4.9.3/../../../../lib/crt0.o:/usr/src/debug/cygwin-2.4.1-1/winsup/cygwin/crt0.c:23: first defined here
test:cygming-crtbegin.c:(.text+0x60): multiple definition of `__gcc_register_frame'
/usr/lib/gcc/x86_64-pc-cygwin/4.9.3/crtbegin.o:cygming-crtbegin.c:(.text+0x10): first defined here
test:cygming-crtbegin.c:(.text+0xd0): multiple definition of `__gcc_deregister_frame'
/usr/lib/gcc/x86_64-pc-cygwin/4.9.3/crtbegin.o:cygming-crtbegin.c:(.text+0x80): first defined here
test:crt0.c:(.data+0x0): multiple definition of `__dso_handle'
/usr/lib/gcc/x86_64-pc-cygwin/4.9.3/crtbegin.o:cygming-crtbegin.c:(.data+0x0): first defined here
test:crt0.c:(.text+0x50): multiple definition of `.weak._Jv_RegisterClasses.__dso_handle'
/usr/lib/gcc/x86_64-pc-cygwin/4.9.3/crtbegin.o:cygming-crtbegin.c:(.text+0x0): first defined here
test:crt0.c:(.idata+0x1d0): multiple definition of `__imp__ZSt3cin'
test:crt0.c:(.idata+0x1d0): first defined here
test:crt0.c:(.idata+0x1d8): multiple definition of `__imp__ZSt4cout'
test:crt0.c:(.idata+0x1d8): first defined here
/tmp/ccG5Ono8.o:test.cpp:(.text+0x0): multiple definition of `main'
test:test.cpp:(.text+0xe0): first defined here
/tmp/ccG5Ono8.o:test.cpp:(.rdata$.refptr._ZSt4cout[.refptr._ZSt4cout]+0x0): multiple definition of `.refptr._ZSt4cout'
test:test.cpp:(.rdata+0xb0): first defined here
/tmp/ccG5Ono8.o:test.cpp:(.rdata$.refptr._ZSt3cin[.refptr._ZSt3cin]+0x0): multiple definition of `.refptr._ZSt3cin'
test:cygming-crtbegin.c:(.rdata+0xa0): first defined here
/tmp/ccG5Ono8.o:test.cpp:(.rdata$.refptr._ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_[.refptr._ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_]+0x0): multiple definition of `.refptr._ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_'
test:test.cpp:(.rdata+0xc0): first defined here
/tmp/ccG5Ono8.o:test.cpp:(.rdata$.refptr.__dso_handle[.refptr.__dso_handle]+0x0): multiple definition of `.refptr.__dso_handle'
test:test.cpp:(.rdata+0xd0): first defined here
/tmp/ccG5Ono8.o:test.cpp:(.rdata$.refptr._ZNSt8ios_base4InitD1Ev[.refptr._ZNSt8ios_base4InitD1Ev]+0x0): multiple definition of `.refptr._ZNSt8ios_base4InitD1Ev'
test:cygming-crtbegin.c:(.rdata+0x90): first defined here
/tmp/ccG5Ono8.o:test.cpp:(.rdata$.refptr._ZSt3cin[.refptr._ZSt3cin]+0x0): multiple definition of `__fu0__ZSt3cin'
test:cygming-crtbegin.c:(.rdata+0xa0): first defined here
/tmp/ccG5Ono8.o:test.cpp:(.rdata$.refptr._ZSt4cout[.refptr._ZSt4cout]+0x0): multiple definition of `__fu1__ZSt4cout'
test:test.cpp:(.rdata+0xb0): first defined here
/usr/lib/gcc/x86_64-pc-cygwin/4.9.3/crtbegin.o:cygming-crtbegin.c:(.text+0x35): undefined reference to `_Jv_RegisterClasses'
/usr/lib/gcc/x86_64-pc-cygwin/4.9.3/crtbegin.o:cygming-crtbegin.c:(.text+0x35): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `_Jv_RegisterClasses'
collect2: error: ld returned 1 exit status
./test.exe
Any ideas on why I am getting this?
The problem I'm facing is difficult to describe and explain, but let's try...
Enrivornment: Ubuntu, C++ and g++
So I have an hierarchy of c++ projects and namespaces:
main: My main program - that calls....
objectaccess: Access objects (read, write, update, delete) - that calls...
commonaccess: Encapsulate access to sqlite3 functions (sqlite3_open, sqlite3_exec, etc.) - that calls...
sqlite3.so: The Sqlite3 library.
So, an example call code would be:
#include "objectaccess.hpp"
#include "commonaccess.hpp"
int main()
{
int id = 10;
myobjecttype mo = objectaccess::get(id);
}
At objectaccess I have:
#include "commonaccess.hpp"
namespace objectaccess {
myobjecttype get(int id)
{
myobjecttype mo = commonaccess::getFromTableX(id);
return mo;
}
}
At commonaccess I have:
#include <sqlite3.h>
namespace commonaccess {
myobjecttype getFromTableX(int id)
{
sqlite3_init(whatever...);
sqlite3_exe(whatever...);
myobjecttype retobject;
retobject.whatever = data1;
return retobject;
}
}
The code runs fine and is tested, except for one problem. All three namespaces are in different projects delivering a dynamic library (commonaccess.so and objectaccess.so) except for the main program that returns a binary executable.
My problem is:
At main, if I make a call to any of commonaccess functions, I get the following errors on linking:
g++ -L"/home/workspace/objectaccess/Debug"
-L"/home/workspace/commonaccess/Debug"
-L/usr/lib/i386-linux-gnu -Xlinker -rpath="./" -o "test" ./src/test.o
-lsqlite3 -lobjectaccess -lcommonaccess
/home/workspace/commonaccess/Debug/libcommonaccess.so: undefined reference to `sqlite3_close'
/home/workspace/commonaccess/Debug/libcommonaccess.so: undefined reference to `sqlite3_exec'
/home/workspace/commonaccess/Debug/libcommonaccess.so: undefined reference to `sqlite3_free'
/home/workspace/commonaccess/Debug/libcommonaccess.so: undefined reference to `sqlite3_errmsg'
/home/workspace/commonaccess/Debug/libcommonaccess.so: undefined reference to `sqlite3_open'
/home/workspace/commonaccess/Debug/libcommonaccess.so: undefined reference to `sqlite3_last_insert_rowid'
collect2: error: ld returned 1 exit status
This is simply solved adding at main() a call to any function of commonaccess, like:
#include "objectaccess.hpp"
#include "commonaccess.hpp"
int main()
{
commonaccess::dummycall();
int id = 10;
myobjecttype mo = objectaccess::get(id);
}
Actually calling a dummy function is not desired, so:
a) Why the linker is not being able to solve these references without directly calling any of the commonaccess functions?
b) Why only adding a call to the lower hierarchy namespace in the main program "teaches" the linker about real reference to sqlite3 functions?
Switch the order of libraries being linked. GNU linker can't reorder them, nor keeps references to calls not used so far, so -lsqlite3 is currently useless. Put it after the library that actually uses sqlite3 calls, something like g++ -L"/home/workspace/objectaccess/Debug" -L"/home/workspace/commonaccess/Debug" -L/usr/lib/i386-linux-gnu -Xlinker -rpath="./" -o "test" ./src/test.o -lobjectaccess -lcommonaccess -lsqlite3
Recently I learned the beautiful language D, which is so more plastic and helps yourself writing stable fast programs. But its not popular... because few code written on D and so more on C and C++. Therefore after I read the book of Andrei Alexanderscu where author very superficially described question about linking of D library to C++ code, I tried learn it myself and written some code on D where defined function that returns an instance of CompleteAutomata class which implements AutomataInterface defined also in C++ code:
#ifndef AUTOMATAINTERFACE_H
#define AUTOMATAINTERFACE_H
class AutomataInterface {
public:
virtual ~AutomataInterface() {}
virtual void next() = 0;
virtual void save() = 0;
virtual void restore() = 0;
virtual void zerofile() = 0;
virtual void invert(unsigned long x, unsigned long y) = 0;
virtual int state(unsigned long x, unsigned long y) const = 0;
virtual unsigned long x() const = 0;
virtual unsigned long y() const = 0;
};
AutomataInterface *createAutomata(unsigned long x, unsigned long y);
#endif // AUTOMATAINTERFACE_H
Relevant D code:
import agregator; // this is my own lib
extern(C++) {
interface AutomataInterface {
void next();
void save();
void restore();
void zerofile();
void invert(size_t x, size_t y);
int state(size_t x, size_t y) const;
size_t x() const;
size_t y() const;
}
AutomataInterface createAutomata(ulong x, ulong y) {
return new CompleteAutomata(x, y);
}
}
export class CompleteAutomata : AutomataInterface {
// instance variables...
this(size_t x, size_t y) { /* ... */ }
extern(C++) {
override void next() {
// ...
}
// others overridden interface methods...
}
}
After code had written, I've compiling of D library by two different compilers (dmd and gdc), with following flags:
dmd -release -O -lib -odlib -ofliblife.h *.d
or
gdc -frelease -O2 -Wall -c *.d
ar cq lib/liblife.a *.o
When I trying link each of received libs to Qt project by adding path to library dir (-L option) and adding a lib directly (-l option). I got errors of in both cases.
In first dmd case I have "undefined reference to `_d_newclass'" and couple of another errors:
g++ -Wl,-O1 -Wl,-z,relro -o automata main.o mainwindow.o renderarea.o button.o playbutton.o moc_mainwindow.o moc_renderarea.o moc_button.o moc_playbutton.o -L/home/newmen/projects/d/life/lib -llife -lQtGui -lQtCore -lpthread
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1fe_5b0.o): In function `createAutomata(unsigned int, unsigned int)':
complete_automata.d:(.text._Z14createAutomatajj+0x27): undefined reference to `_d_newclass'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.data+0x0): undefined reference to `_D14TypeInfo_Class6__vtblZ'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.data+0x50): undefined reference to `_D6Object7__ClassZ'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.data+0xd0): undefined reference to `_D14TypeInfo_Class6__vtblZ'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.data+0x120): undefined reference to `_D6Object7__ClassZ'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x68): undefined reference to `_D6object6Object8toStringMFZAya'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x70): undefined reference to `_D6object6Object6toHashMFNbNeZm'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x78): undefined reference to `_D6object6Object5opCmpMFC6ObjectZi'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x80): undefined reference to `_D6object6Object8opEqualsMFC6ObjectZb'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0xf8): undefined reference to `_D6object6Object8toStringMFZAya'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x100): undefined reference to `_D6object6Object6toHashMFNbNeZm'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x108): undefined reference to `_D6object6Object5opCmpMFC6ObjectZi'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x110): undefined reference to `_D6object6Object8opEqualsMFC6ObjectZb'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o): In function `_D17complete_automata16CompleteAutomata6__ctorMFmmZC17complete_automata16CompleteAutomata':
complete_automata.d:(.text._D17complete_automata16CompleteAutomata6__ctorMFmmZC17complete_automata16CompleteAutomata+0x1f): undefined reference to `_d_newclass'
complete_automata.d:(.text._D17complete_automata16CompleteAutomata6__ctorMFmmZC17complete_automata16CompleteAutomata+0x46): undefined reference to `_d_newclass'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o): In function `CompleteAutomata::next()':
complete_automata.d:(.text._ZN16CompleteAutomata4nextEv+0x2f): undefined reference to `_d_newclass'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o): In function `CompleteAutomata::save()':
complete_automata.d:(.text._ZN16CompleteAutomata4saveEv+0x25): undefined reference to `_adDupT'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o): In function `CompleteAutomata::restore()':
complete_automata.d:(.text._ZN16CompleteAutomata7restoreEv+0x33): undefined reference to `_d_newclass'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o): In function `CompleteAutomata::zerofile()':
complete_automata.d:(.text._ZN16CompleteAutomata8zerofileEv+0x2f): undefined reference to `_d_newclass'
/home/newmen/projects/d/life/lib/liblife.a(object_201_8b7.o): In function `no symbol':
/usr/include/dmd/druntime/import/object.di:(.text+0x6): undefined reference to `_Dmodule_ref'
/home/newmen/projects/d/life/lib/liblife.a(object_201_8b7.o):(.data._D12TypeInfo_Axi6__initZ+0x0): undefined reference to `_D14TypeInfo_Array6__vtblZ'
/home/newmen/projects/d/life/lib/liblife.a(object_201_8b7.o): In function `_D46/usr/include/dmd/druntime/import/object.di.5137__arrayZ':
/usr/include/dmd/druntime/import/object.di:(.text._D46/usr/include/dmd/druntime/import/object.di.5137__arrayZ+0x16): undefined reference to `_d_array_bounds'
/home/newmen/projects/d/life/lib/liblife.a(object_201_8b7.o): In function `_D46/usr/include/dmd/druntime/import/object.di.5138__assertFiZv':
/usr/include/dmd/druntime/import/object.di:(.text._D46/usr/include/dmd/druntime/import/object.di.5138__assertFiZv+0x16): undefined reference to `_d_assertm'
/home/newmen/projects/d/life/lib/liblife.a(object_201_8b7.o): In function `_D46/usr/include/dmd/druntime/import/object.di.51315__unittest_failFiZv':
/usr/include/dmd/druntime/import/object.di:(.text._D46/usr/include/dmd/druntime/import/object.di.51315__unittest_failFiZv+0x16): undefined reference to `_d_unittestm'
/home/newmen/projects/d/life/lib/liblife.a(object_203_875.o): In function `no symbol':
/usr/include/dmd/druntime/import/object.di:(.text+0x6): undefined reference to `_Dmodule_ref'
/home/newmen/projects/d/life/lib/liblife.a(object_203_875.o):(.data._D11TypeInfo_xi6__initZ+0x0): undefined reference to `_D14TypeInfo_Const6__vtblZ'
/home/newmen/projects/d/life/lib/liblife.a(object_203_875.o):(.data._D11TypeInfo_xi6__initZ+0x10): undefined reference to `_D10TypeInfo_i6__initZ'
/home/newmen/projects/d/life/lib/liblife.a(object_203_875.o): In function `_D46/usr/include/dmd/druntime/import/object.di.5157__arrayZ':
/usr/include/dmd/druntime/import/object.di:(.text._D46/usr/include/dmd/druntime/import/object.di.5157__arrayZ+0x16): undefined reference to `_d_array_bounds'
/home/newmen/projects/d/life/lib/liblife.a(object_203_875.o): In function `_D46/usr/include/dmd/druntime/import/object.di.5158__assertFiZv':
/usr/include/dmd/druntime/import/object.di:(.text._D46/usr/include/dmd/druntime/import/object.di.5158__assertFiZv+0x16): undefined reference to `_d_assertm'
/home/newmen/projects/d/life/lib/liblife.a(object_203_875.o): In function `_D46/usr/include/dmd/druntime/import/object.di.51515__unittest_failFiZv':
/usr/include/dmd/druntime/import/object.di:(.text._D46/usr/include/dmd/druntime/import/object.di.51515__unittest_failFiZv+0x16): undefined reference to `_d_unittestm'
/home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `no symbol':
agregator.d:(.text+0x6): undefined reference to `_Dmodule_ref'
/home/newmen/projects/d/life/lib/liblife.a(agregator.o):(.data+0x10): undefined reference to `_D3std6random12__ModuleInfoZ'
/home/newmen/projects/d/life/lib/liblife.a(agregator.o):(.rodata+0x20): undefined reference to `_D14TypeInfo_Class6__vtblZ'
/home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `_D9agregator7__arrayZ':
agregator.d:(.text._D9agregator7__arrayZ+0x16): undefined reference to `_d_array_bounds'
/home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `_D9agregator8__assertFiZv':
agregator.d:(.text._D9agregator8__assertFiZv+0x16): undefined reference to `_d_assertm'
/home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `_D9agregator15__unittest_failFiZv':
agregator.d:(.text._D9agregator15__unittest_failFiZv+0x16): undefined reference to `_d_unittestm'
/home/newmen/projects/d/life/lib/liblife.a(agregator_2_5fd.o):(.data+0x0): undefined reference to `_D14TypeInfo_Class6__vtblZ'
/home/newmen/projects/d/life/lib/liblife.a(agregator_2_5fd.o):(.data+0x50): undefined reference to `_D6Object7__ClassZ'
/home/newmen/projects/d/life/lib/liblife.a(agregator_2_5fd.o):(.rodata+0x48): undefined reference to `_D6object6Object8toStringMFZAya'
...
In second case (when using gdc) I receives message about "multiple definition of":
g++ -Wl,-O1 -Wl,-z,relro -o cellular_life main.o mainwindow.o renderarea.o button.o playbutton.o moc_mainwindow.o moc_renderarea.o moc_button.o moc_playbutton.o -L/home/newmen/projects/d/life/lib -llife -lQtGui -lQtCore -lpthread
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `_D17complete_automata16CompleteAutomata7restoreMRZv14SliceAgregator9initValueMxFmmZi':
complete_automata.d:(.text+0x0): multiple definition of `_D17complete_automata16CompleteAutomata7restoreMRZv14SliceAgregator9initValueMxFmmZi'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._D17complete_automata16CompleteAutomata7restoreMRZv14SliceAgregator9initValueMxFmmZi+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::invert(unsigned long long, unsigned long long)':
complete_automata.d:(.text+0x40): multiple definition of `CompleteAutomata::invert(unsigned long long, unsigned long long)'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZN16CompleteAutomata6invertEyy+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::state(unsigned long long, unsigned long long) const':
complete_automata.d:(.text+0x60): multiple definition of `CompleteAutomata::state(unsigned long long, unsigned long long) const'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZNK16CompleteAutomata5stateEyy+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::x() const':
complete_automata.d:(.text+0x80): multiple definition of `CompleteAutomata::x() const'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZNK16CompleteAutomata1xEv+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::y() const':
complete_automata.d:(.text+0xa0): multiple definition of `CompleteAutomata::y() const'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZNK16CompleteAutomata1yEv+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::next()':
complete_automata.d:(.text+0x140): multiple definition of `CompleteAutomata::next()'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZN16CompleteAutomata4nextEv+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.tbss+0x10): multiple definition of `_D17complete_automata16CompleteAutomata4nextMRZv7changerC7changer7Changer'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.tbss+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::restore()':
complete_automata.d:(.text+0x1b0): multiple definition of `CompleteAutomata::restore()'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZN16CompleteAutomata7restoreEv+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.tbss+0x8): multiple definition of `_D17complete_automata16CompleteAutomata7restoreMRZv9agregatorC9agregator9Agregator'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.tbss+0x8): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.data+0x180): multiple definition of `_D_ZN16CompleteAutomata7restoreEv14SliceAgregator7__ClassZ'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.data+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::zerofile()':
complete_automata.d:(.text+0x220): multiple definition of `CompleteAutomata::zerofile()'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZN16CompleteAutomata8zerofileEv+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.tbss+0x0): multiple definition of `_D17complete_automata16CompleteAutomata8zerofileMRZv9agregatorC9agregator9Agregator'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.tbss+0x10): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::save()':
complete_automata.d:(.text+0x290): multiple definition of `CompleteAutomata::save()'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._ZN16CompleteAutomata4saveEv+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.data+0x80): multiple definition of `_D17complete_automata16CompleteAutomata7__ClassZ'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.data+0xd0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `_D17complete_automata16CompleteAutomata6__ctorMFmmZC17complete_automata16CompleteAutomata':
complete_automata.d:(.text+0x9b0): multiple definition of `_D17complete_automata16CompleteAutomata6__ctorMFmmZC17complete_automata16CompleteAutomata'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):complete_automata.d:(.text._D17complete_automata16CompleteAutomata6__ctorMFmmZC17complete_automata16CompleteAutomata+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.rodata+0x420): multiple definition of `_D17complete_automata16CompleteAutomata6__vtblZ'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0xf0): first defined here
/usr/bin/ld: Warning: size of symbol `_D17complete_automata16CompleteAutomata6__vtblZ' changed from 104 in /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o) to 112 in /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o)
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.rodata+0x4a0): multiple definition of `_D17complete_automata16CompleteAutomata6__initZ'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x90): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.rodata+0x4e0): multiple definition of `_D_ZN16CompleteAutomata7restoreEv14SliceAgregator6__vtblZ'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x60): first defined here
/usr/bin/ld: Warning: size of symbol `_D_ZN16CompleteAutomata7restoreEv14SliceAgregator6__vtblZ' changed from 48 in /home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o) to 56 in /home/newmen/projects/d/life/lib/liblife.a(complete_automata.o)
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o):(.rodata+0x520): multiple definition of `_D_ZN16CompleteAutomata7restoreEv14SliceAgregator6__initZ'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1ff_675.o):(.rodata+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `_D3std7complex14__T7ComplexTeZ7Complex8toStringMxFMDFAxaZvAyaZAya12__lambda1223MFNbNfAxaZv':
agregator.d:(.text+0xaf): undefined reference to `_D11TypeInfo_Aa6__initZ'
agregator.d:(.text+0xb7): undefined reference to `_d_arrayappendT'
/home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `_D3std4conv16__T6toImplTiTxkZ6toImplFNaNfxkZi15__dgliteral1389MFNaNfZC6object9Throwable':
agregator.d:(.text+0xc5): undefined reference to `_D3std4conv21ConvOverflowException7__ClassZ'
agregator.d:(.text+0xca): undefined reference to `_d_newclass'
agregator.d:(.text+0xed): undefined reference to `_D3std4conv21ConvOverflowException6__ctorMFAyaAyamZC3std4conv21ConvOverflowException'
/home/newmen/projects/d/life/lib/liblife.a(agregator.o): In function `_D3std6format17__T9getNthIntTxeZ9getNthIntFNaNfkxeZi.part.6':
agregator.d:(.text+0x105): undefined reference to `_D3std6format15FormatException7__ClassZ'
agregator.d:(.text+0x10a): undefined reference to `_d_newclass'
...
After two days of attempts to do so...
Recently I've try add Phobos (D standard library) to linking process. For dmd -lphobos2 flag and for gdc -lgphobos2 flag correspond. But it not help me...
When using dmd linker output:
g++ -Wl,-O1 -Wl,-z,relro -o cellular_life main.o mainwindow.o renderarea.o button.o playbutton.o moc_mainwindow.o moc_renderarea.o moc_button.o moc_playbutton.o -L/home/newmen/projects/d/life/lib -llife -lQtGui -lQtCore -lpthread -lphobos2
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to `curl_easy_duphandle#CURL_GNUTLS_3'
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to `curl_easy_strerror#CURL_GNUTLS_3'
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to `curl_slist_free_all#CURL_GNUTLS_3'
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to `curl_global_init#CURL_GNUTLS_3'
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to `curl_easy_perform#CURL_GNUTLS_3'
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to `curl_easy_init#CURL_GNUTLS_3'
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to `curl_easy_pause#CURL_GNUTLS_3'
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to `_Dmain'
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to `curl_easy_setopt#CURL_GNUTLS_3'
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to `curl_slist_append#CURL_GNUTLS_3'
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to `curl_global_cleanup#CURL_GNUTLS_3'
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/libphobos2.so: undefined reference to `curl_easy_cleanup#CURL_GNUTLS_3'
collect2: error: ld returned 1 exit status
make: *** [cellular_life] Error 1
and I've try substitute of libcurl-gnutls: ln -s /usr/lib64/libcurl.so.4 /usr/lib64/libcurl-gnutls.so.4. Then result of linking the same but without message about libcurl-gnutls.
When using gdc linker output again talk about "multiple definition to":
/home/newmen/gcc/bin/g++ -Wl,-O1 -Wl,-z,relro -o cellular_life main.o mainwindow.o renderarea.o button.o playbutton.o moc_mainwindow.o moc_renderarea.o moc_button.o moc_playbutton.o -L/home/newmen/gcc/lib64 -L/home/newmen/projects/d/life/lib -llife -lQtGui -lQtCore -lpthread -lgphobos2
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `_D17complete_automata16CompleteAutomata7restoreMRZv14SliceAgregator9initValueMxFmmZi':
complete_automata.d:(.text+0x0): multiple definition of `_D17complete_automata16CompleteAutomata7restoreMRZv14SliceAgregator9initValueMxFmmZi'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1e3_675.o):complete_automata.d:(.text._D17complete_automata16CompleteAutomata7restoreMRZv14SliceAgregator9initValueMxFmmZi+0x0): first defined here
/home/newmen/projects/d/life/lib/liblife.a(complete_automata.o): In function `CompleteAutomata::invert(unsigned long long, unsigned long long)':
complete_automata.d:(.text+0x40): multiple definition of `CompleteAutomata::invert(unsigned long long, unsigned long long)'
/home/newmen/projects/d/life/lib/liblife.a(complete_automata_1e3_675.o):complete_automata.d:(.text._ZN16CompleteAutomata6invertEyy+0x0): first defined here
...
/home/newmen/gcc/lib64/libgphobos2.a(dmain2.o): In function `main':
/home/newmen/projects/distrib/gcc-4.8.1/x86_64-unknown-linux-gnu/libphobos/libdruntime/../../.././libphobos/libdruntime/rt/dmain2.d:394: multiple definition of `main'
main.o:/home/newmen/projects/d/life/qt_viewer/main.cpp:5: first defined here
/usr/bin/ld: /home/newmen/gcc/lib64/libgphobos2.a(time.o): undefined reference to symbol 'clock_getres##GLIBC_2.2.5'
/usr/bin/ld: note: 'clock_getres##GLIBC_2.2.5' is defined in DSO /lib64/librt.so.1 so try adding it to the linker command line
/lib64/librt.so.1: could not read symbols: Invalid operation
collect2: error: ld returned 1 exit status
make: *** [cellular_life] Error 1
with message about librt.so.1 at end. I inspect /usr/lib64 and seen there it library file.
Dear magic, please tell me how to connect the D library to C++ code.
It is generally easier to let the D compiler do the linking:
g++ -c yourfile.cpp
dmd yourfile.o d_file.d
You might have to add curl to it as well, same as you did before. To pass a linker argument through dmd (or gdmd if you're using gdc, should work the same way), pass -Larg
dmd yourfile.o d_file.d -L-lstdc++ -L-lcurl -L-lQtGui # and so on
It is generally easier to put main() in D too (it can just immediately call out to a C++ defined function too) because otherwise you'll probably have to initialize the D runtime before using it from C++.
But to finish the process you've started... first thing, looks like your liblife.a has the same file added twice. I'd try deleting that file and recreating it, or just skipping that step and passing the .o files to the linker directly without first packing them into a .a. That'll simplify things a bit.
My other question is: why is it trying to pull the D main? Is there a main() in your .d code somewhere? If so, that's ok, but you'll have to remove the one from your C++ code. (Perhaps rename it into cppmain and then call it from the D main:
D code:
extern(C++) int cppmain(int argc, char** argv);
int main() {
import core.runtime;
return cppmain(Runtime.cArgs.argc, Runtime.cArgs.argv);
}
And that will forward to your C++ main. If you want to remove the D main (assuming it is there, if not let me know and I'll try to think what else could cause that linker error), before tou use D code in C++, you'll want to initialize D. So:
D code:
extern(C++) void initD() {
import core.runtime;
Runtime.initialize();
}
C++ code:
extern "C++" void initD();
int main() {
initD();
// the rest of your stuff
}
If you don't do that, calling D functions is liable to cause a segfault.
But to sum up, I'm pretty sure you have a duplicate .o file added to your archive, and main defined in both D and C++. Delete the duplicate in the archive and kill one of the duplicate mains and you should have some success.
My compiler issued the following error :
matrix.o: In function `Matrix::modify_cell(unsigned int, unsigned int, int)':
Matrix.cpp:(.text+0x5f): undefined reference to `operator!(Dim)'
Matrix.cpp:(.text+0xa3): undefined reference to `operator!(Dim)'
Matrix.cpp:(.text+0x178): undefined reference to `operator!(Dim)'
Matrix.cpp:(.text+0x1a0): undefined reference to `operator!(Dim)'
matrix.o: In function `List::nula(Dim) const':
Matrix.cpp:(.text._ZNK4List4nulaE3Dim[List::nula(Dim) const]+0x11): undefined reference to `operator!(Dim)'
list1.o:List - auxiliary methods.cpp:(.text+0x3b): more undefined references to `operator!(Dim)' follow
collect2: ld returned 1 exit status
make: *** [app] Error 1
Matrix is a class placed in file Matrix.h and Matrix.cpp that inherits from the class List, that in turn is placed in List.h and two other .cpp files. Type Dim (typedef) and operator! for it are declared globally (outside of any class) in aux.h included to List.h and the operator! is defined in aux.cpp. In Matrix.h I include List.h so I do not understand what is the problem. aux.cpp is indeed compiled in my makefile to .o and then joined into single app.
I know that it would be better to place my typedef Dim and its overloaded operator into a class, but it is used both in class List and class Matrix while typedefs are not inherited and I have no idea for any other workaround.
EDIT:
// aux.cpp
#include "aux.h"
Dim operator!(Dim dim) { return dim == COL ? ROW : COL; }
// aux.h
#ifndef AUX_H
#define AUX_H
/* (...) */
typedef enum { ROW, COL } Dim;
inline Dim operator!(Dim dim);
#endif
You've declared operator!(Dim) as inline, so it isn't available unless you also include the definition in the .h. Either move the definition or take out the inline.